Was an intern for Lexmark (who made Dell printers for at least a while). The drums are charged up with a roller, discharged to ground by the laser, then pick up toner electrostatically where still charged. The toner is then transferred electrostatically to the plastic transfer belt, which is later transferred to the paper electrostatically. They use the belt so the colors register with one another; that can't be done well enough by transferring each color to paper independently. Getting the belt to track well on the rollers is quite complicated, and I believe was done mechanically with linkages and springs to steer it passively Voltages are on the order of 0.8-3kV. The process is very sensitive to environmental conditions (humidity, etc) and paper type. The engineering effort is tremendous. There is probably an output paperpath team. I sat in on some meetings where they were doing explicit dynamic FEA (very computation intensive) of the transfer belt because of some issues they were having that required an extremely good model of friction. I collected some data to validate photoconductivity FEA models (among other things). People maintain tables of the circumference of all of the rollers so if they have a periodic print defect, you can trace back which roller it's coming from.
Have definitely seen some ultra-high-end production laser presses that don't do the transfer roll dance and do actually deposit the 4 (or more, because spot color toners and MICR and shit) colors independently. IIRC each color even has a separate fuser. Only time I saw it cause trouble with color registration was when we were printing on a plastic substrate that thermally expanded with each fuser pass. But those cost house (or office building) money. And don't fit in dumpsters. Sometimes not even roll-offs.
@@robertengland8285 As a Dell warranty vendor, last I heard, Dell was getting out of the printer business and instead selling printers from various brands bundled in online after the sale. I think Dell officially quit all imagining product sales in 2018. And YES that is a Xerox OEM. And as of today, Lexmark also used Xerox as an a3(11x17) OEM.
Loved the “that’s just a roller that rolls” comment in the video. That is a high voltage transfer roller and probably the cause of all the lines on the prints. The light pipe is an erase lamp to help clear the latent image from the drums. Liked this video. Reminds me of days when I used to have to train engineers on servicing these. I was a trainer for Lexmark, Xerox, HP, Canon and Epson in the past, as well as IBM, Fujitsu, Ricoh and Hitachi huge high speed printers that connect to mainframes. Amazing really that from the smallest printer up to the 2000+ feet per minute continuous machines the tech, fused aside, was essentially the same.
I started working on these back in 1981 ... I'm studied electronics tech in college ( EET ) shortly after returning from Sydney, Australia (2 years LDS Mission) I answered a help wanted ad and have doing it ever since. Started my own copier printer business 28 years ago and am pretty much retired now. I started with black and white liquid toned copiers, then went on to dry toned machines, then machines with Document feeders and sorters, then came Fax machines ... Roll coated paper, then plain paper, then scanning. as technology moved forward ... the amount and size of parts shrank, motors were driven both directions and one way clutches enabled one motor to have 2 functions, magnetic clutches and one way clutches brought down the part count ... the electronic complexity increased exponentially. Customers used to use a Copier, a Fax Machine, a Printer, and a Scanner ... then someone thought to combine them all into one unit !! the only problem with that was that a simple paper jam brought the whole office down. It's been an interesting career and I've always said that someday I'll write a book about it !! As a side note ... many of these machines aren't even made by the people whose name is on the front ... same goes for most consumer electronics. The parts are sourced from all over the world and parts from one machine sometimes were the same as another machine, ex: Canon built HP printers, Lexmark used to be Toshiba, Dell was made by Lexmark. who got the machine from Toshiba ... Savin, Gestetner, Nashuatec are all built by Ricoh. Xerox hasn't built anything for years, they have put their name on machines from Sharp, Toshiba and Samsung ... As I hear it in the industry, HP bought Samsung's printer business, Xerox has tried to buy HP ....... the reason toner is expensive is because of the chip that the manufactures put on the cartridge, trying to keep you from using third part Ink / Toner ... HP used the same black toner from the old HP2's for many. many years ! ( It's been an interesting ride ) I get a kick out of how excited you get over an old copier or printer ... I watch a lot of your videos ... interesting to see what makes something work ... everything we use today started out with a copier that relied on a big motor, chains, gears, relays, micro switches, Heat lamps and Semi-conductive image drums. Keep up the good work ... enjoy your videos !! Mike
I always found it funny that people get so impressed seeing a 3d printer work, while it only has 3 stepper motors and a heated extruder in it. At the same time, these people own laser printers themselves and are mostly pissed at how crappy their printers are.
Laser printers hide the complexity, and are so good that people forget exactly how complex it actually is, till it has an issue. If somebody made a transparent case laser to show how it all goes together (hard, seeing just how many parts of the process are light sensitive, and how many optical sensors there are in there) you would be impressed. Then show them the operation of an offset printer, where it is all out in the open and is all "no touchee or losie fingery" and they think that is complex. Digital plate printer is 1000 times as complex, but is all covered, and costs $30 million, but you only press a few buttons and it does it all by itself. It does not look as impressive, even if it covers 30m of floor and is 5m wide. Roll in one side, finished sheets out the other side. Visited our one printer, and got the tour. Hearing protection not optional.
@@RavenWolfRetroTech I think you've made a false assumption. This could be a pretty old device, or at least an old engine design. As Dave kept pointing out, there's a HUGE amount of engineering that went into the print engine's mechanical design, so Xerox (as the engine OEM has been identified as) would want to use that engine design in as many models as possible to get the most value out of the design. That device might be over 20 years old (actually having a Centronics port suggests it's a vintage model, although interfaces are generally cheap bolt-ons for modern devices), and the engine design might well be 30.
@@evensgrey That may be so and considering my expertise is in Canon based engines like HP and larger equipment, particularly Ricoh, it may be a manufacturer idiosyncrasy. That printer looks a LOT like a Hitachi design but I'm pretty certain that all Dells were Lexmark. Being that it is color and uses an intermediate transfer belt, I would not think it could be older than 2004ish. I am certain they would not put that there without a reason so it makes me curious as to why? I generally deal with much older printers these days but, in general, blank lamps were used to erase the remaining drum charge on corona wire based systems since the corona is additive and you would get ghost images. A PCR is in physical contact with the drum so it levels the charge on its own while using about 10-15% of the power needed for a corona. @peter Paolucci is absolutely correct what that is for but I am curious why it was needed
High voltage board salvage the high voltage resistors out of there, as they are useful to build a DIY high voltage probe, using the 2kv rated resistors.
@@EEVblog Great video idea indeed. Is there a chance to do something like this? Obv with disclaimers as stated. A simple HV probe setup for the home user would be petty nifty. Obviously not a replacement (or could be?) for a proper set like the EEVblog set.
@@CliveChamberlain946 Depends on the printer, but with a colour laser you will have at least 6 different HV sources in the unit, a regular mono laser 3, as one for the drum, one for the transfer roller and one for the pre charge on the drum. You will need to look for the AC pre transfer to see the capacitor value they use for compensation, as that is the only one that is AC signal, the rest are all DC. Only one without a big ceramic capacitor though, and generally a separate black potted unit.
The disadvantage of parting out such a thing is that you are left with 5 times as much trash as you started with! You get the couple of parts that are interesting and put them in the parts boxes but now you have a car trunk full of trash to haul away to the recycling center :-(
I was a repair guy on the Dell 5100CN printers. and i still use one, those toner cartridges, i got about 30 news ones. those printers will print edge to edge on both sides at about 2 seconds per page. to bad you trashed it, a clean up and those lines would have gone away.
I found it very interesting and doubt that once you have seen inside the laser scanning mechanism you could get it all back together without spending more than a month! Yeah it wasn't really trashed, have you seen some channels where they literally take a baseball bat to new gear just for views? Companies, retail or whatever regularly chuck gear when their leases expire or auction it off, keep your eyes open for an opportunity of a business shutting up shop and I am sure you will be able to get a free laser printer.
22:28 those gears with the helical ramps; the ramps are slipper clutches. Since steppers are known for producing large amounts of torque, you need a passive means of torque limiting so they don't strip the gears if there is a jam. There is likely springs that push on one side of the gears to provide preload on the helix and give the right amount of overload tension. The helix angle will match the helical gear angle so it cams out at the same gear timing angle so there is no advance or retard as it cams out.
The angle would not be the same if you want to use it as an overload clutch as there would be opposing force that kept it in place. However the ramp angle is very shallow so it will climb that against any kind of helix angle. The timing will suffer but I think this may have been to drive the toner fill or recovery augers so timing does not matter. The printer would detect the slip in some way and decide the auger was stuck due to toner recovery bin too full or if it stirred first one way against the shoulder to mix the supply and then turned against the ramp to level and detect the toner. The designers have a whole book of sneaky tricks that they use to do two functions with one part or sensor.
I was thinking the were there to allow for manual clearing of paper jams, enabling the output path rollers to turn independent of the drive motor / gearing.
I remember the first laser printer I ripped apart for the stepper motor parts, that was when I was first getting into tinkering with electronics! Now I have a closet full of them.... and I had to get shelves to hold all the small form-factor PCs... I can stop anytime I want though!
I'm a wood, metal, scrap and brass collector of 7 + years. My mum and grandpa collected. Now I only have 2 square metres left in my bedroom. I need a skip bin for my next birthday.
They're also good if you want to make a really high quality kaleidoscope. Better mirrors mean the repeated images go "off to infinity" to the sides much further before they become dark or distorted.
Printer tech and trainer from Xerox here, that black linkage @08:00 is a mechanism to disconnect the drive of the colour drums. The colour drums are not driven during B/W printing, extending the life of the drums a bit. The toner supply is controlled with a toner concentration sensor in the drum / developer cartridge. If the sensor sees that there is little toner in the developer, the stepper motors of the cartridges are turned on for a few seconds (2 seconds for this machine). The fresh toner is dispensed in the developer, and mixed in with the developer material. The plastic rod and LED are part of the drum eraser system, It makes the drum electrically neutral and erases the electrostatic residue of the drum. The green stuff on the drum is a photo sensitive layer, so getting rid of electrostatic charge is easy, just shine a light on it. If you have any other questions, let me know
@@vladimir7838 Blue tarp because the toners go all over. Absolute murder to get out of carpet, and as he is renting this area he does not want that charge at end of lease in 3 months. Black is easy to hide, you just do 3 passes with a wet extractor and cold water, with first carpet cleaning detergent, second liquid fabric softener and third with plain water, and it will be almost totally gone from sight. the colours though will still be visible, as they stand out from the dirt. If you still see black in the third pass do the cycle again, but in general when you do the rinse the water will be pale brown.
Yep, but if the Vacuum cleaner develops a leak, you and the whole office are 3 shades darker than when you started that morning, that happened to me once, noticed and shut down the vacuum cleaner … it was bit hazy ..
FYI on cleaning all that horrid toner powder off your hands - use cold water and lots of soap. Hot water will start the setting process and make it harder to clean off :-)
Your water will have to be hotter that 100 deg C. Fuser surfaces runs between 150 an 200 deg C. Does not stop that fine powder from getting trapped in the clothing fiber. If you ever get a toner spill on the floor use a dry cloth or paper towels. a 3M toner vac would be the right thing. You need some real nasty chemicals to desolve it like paint thinners Always wear black...
@@Allan-mf1he Hi Allan. I'm just passing on words of wisdom from an old HP copier tech. He told me that hot water wont set the toner, but it makes it harder to remove. Still prefer Gnomish's suggestion of avoiding it at the start.
@@paulp2089 True avoiding it would be best. Toner over the years also changed quite a bit, its much safer and polymerized vs pulverized making the particles smoother and more uniform in size. Lots of technology going into toner. There is no getting around toner for me working on production machines i look like a miner at the end of the day:).
Take care if you have to vacuum up a big toner spill. The powder has an electrostatic charge to allow it to be picked up by the high voltages. if you suck it up in a vac with a metal nozzle you can make inch-long sparks, normally to your nose when you are looking in the machine. Its the kind of experience you remember. ;-)
Those gears with the ramps obviously allow travel in one direction only so perhaps they allow you to pull the paper out without breaking the geartrain.
Yes the are for what are called relay rollers once the paper have gone from one set of rollers to the next the previous drive can switch of and roll free in the feed direction so the roller set upstream can pull it freely.
RGB adds up to white. CMY adds up to black. if you shine torches with filters onto a wall it shows up additive vs subtractive color easily. It's very interesting for the history of color photography and darkroom printing processes (before this ink and toner based plotters did it better and faster).
And you can really use a colour gamaut diagram to choose any colours you want to be primary colours, as long as they span the colours you wish to produce.
They are so cheap nowadays that you just throw it out when the lines start appearing. Anything older than 5 years is going to have been written off and thus has no value left for the company beancounters.
Mmm mmm, lots of stepper motor goodness. The engineering in these devices is amazing. I always wonder how many model iterations there are over the years using the same "guts", with cosmetic changes.
Quite a few, they tend to change cosmetic parts, and then after a few years change back to the older one, but with a slightly redesigned cartridge, so the old ones are no longer usable.
and the microchips don't actually monitor physical toner level, they are simply eeprom devices that register if the toner was used, and decrements the "full" to "empty" count. You'd be surprised how much toner actually remains in an "empty" cartridge.
- The image is formed on the transfer belt (9:15) by the individual drums. The printer will occasionally print test patterns on the belt for color synchronization and density correction and scan them with sensors without ever needing to actually print them on paper. You won't know this is happening unless you open the door at the right time in the warmup cycle and see the patterns on the belt. - The paper only ever goes up the right side of the machine and comes out the top. The roller at 8:53 presses paper against the transfer belt at the edge and immediately sends it up the fuser. Or in the case of double sided prints will send the paper around through all that extra plastic in the door to print on the back side. - LED and light channel connected to them are for erasing the drums. They are quite effective and are still widely used in copiers and printers today. Actually, They are used along with the corona charge wires (buried in the drum assembly) to make sure that all areas of the drum are being charged and discharged regularly, not just where the printed areas of the page land. - Many of those 4 pin connectors are only for tracking new consumable items like drums and transfer belt. They connect to a "fuse chip" that blow after the printer acknowledges that a new item has been installed. It will reset the page counter for that item then command the chip to blow. Many would think this is a money-making technique, which it sort-of is as you cannot take that item out and install in another printer and have it think it's new. But more importantly the machine will compensate for gradual wear by adjusting voltages etc. which you want reset when you install new items. The Transfer Belt has one of these chips on the back side as seen in 9:39. I do service on these style machines as well as color photocopiers (not dells/lexmarks)
@ 22:40 : nope Dave, except if it's wrote on, it's not an average DC motor but a 3-phased motor (like spinning motor from disk burner/reader or HDD) One of my engineer friends say that's accurate enough for know position (and that's why it's used in these devices) But still keep it (with the power supply board come from printer, high probability that's got +5V/+12V also)
That big flat belt that wouldn't come out at 9:11 is the image tranfer belt. You have to lift the blue handles to pull it out all the way. What happens is each of the 4 drums lays down the different color images onto the belt. When the image is complete, then the belt makes another rotation as the paper passes under it, thereby transferring the image from the belt onto the paper. That is why it is called the transfer belt. This makes the giant printer slow because the belt has to make 2 passes for the image to end up on the paper. So the unwanted line could come from this belt also because there is a cleaning blade that cleans the belt. If the belt is not clean, then you end up with ghost image from the previous print or lines. Drums and fuser roller (heat rollers) can introduce lines too. The more modern color printers deposits the toner straight from the drum to the paper which makes it faster and reduce one less source that can introduce a line on the print! The light pipe at 15:16 is for discharging the drum. It effectively erases the drum so that it is ready to receive another image from the laser. Often when someone worked on a color printer, they end up with psychedelic boogers because they breathed in some of the color toner! 😂
The big brown belt is the transfer belt. The image is built up on it by static from each of the 4 drums. then the foam transfer roller statically charges the paper to transfer the image to the paper. Finally the fuser melts the toner into the paper
I’ve got a box of metric screws from tearing apart printers and copiers, being self employed and re-manufacturing for machines to sell I would buy machines wholesale and “Borg’ify” to get a good unit to sell, also had the toner stained fingers and cuticles !!! Now retired, my hands look normal except from the scars of injuries: shocked, crushed, cut, etc.
These lightstrips are so called pre conditioning exposure light to clear the drums electrostatic charge after a rotation. If this led fails, there could be an image offset of the previous image on the drum. By exposing the drum with light across the full width of the drum whilst rotating, the photoconductive layer starts to conduct and residual static electricity will flow to ground, thereby clearing the charge from the drum. After this the drum is ready for the "new" charge. Corona wires are used less often. Instead transferrollers and primary charging rollers are more common nowadays. Their made of conductive rubber and create a more evenly charge across the drums and paper. Improving image quality and producing less ozone gas. Have a great day, A former Canon techie from Holland.
I have done this for years and have a shed full of parts that eventually will end up in the dumpster...totally worth the time and effort. Cheap thrills! Front surface mirrors are good for kaleidoscopes.
I saved a Dell 4C laser printer from being trashed by my company just because it refused to work with a message saying that the belt's official lifetime was exceeded (100,004 pages printed!). I was not going to accept that. Took me some studying of the really excellent service documentation (it turned out the printer was really a rebranded Xerox) to find that there were two signals going to the drum that were called SDA and SCK - without further explanation what the obvious I²C was used for. :) I then only needed to reprogram the drum's lifetime value in its EEPROM - and the printer booted up fine, and the printing quality is still amazing! These business printers are really a gem of engineering and documentation. Hats off!
As a kid we would go to the dumps with a cardboard box and wire cutters, remove the resistors and capacitors from TV sets. I still have some of those parts laying around somewhere. You run out of room storing junk.
My Brother HL=2140 has been really reliable too. It is only a black and white laser I must have had for more than 7 or 8 years but it has never given me any trouble, other than just ONE paper jam. I have only replaced the toner twice and one of those was that underfilled starter cartridge a lot of printers sometimes come with. It never needed a new drum and still prints like the day we first brought it home. One time I had a problem with dirty looking prints but that was easily fixed by separating the drum and toner cartridges. All I had to do was take it outside and carefully blow the loose toner out of the drum assembly. Now it prints like new again. I once had an Epson Stylus color 200 but that thing kept getting clogged nozzles and wanting new cartridges much too soon. I threw it away!! It is a shame too because it printed much better photos than some of those dedicated photo printers. I had a portable photo printer and it didn't print as sharply and nicely as the Epson did. Still though, I was tired of inkjets and threw the thing away. I never had a printer that was so unreliable. Laser printers are the way to go. Sometimes they can be very expensive but hopefully those ones will last longer than you.
The correct terms are additive and subtractive colour systems. They are complementary in every respect, if you add R and B you get C, if you add G and R you get Y, if you add R and B you get M. Similarly if you substract M and C from W you get B, Y and C from W you get G, and for Y and M from W you get R. K is only there for simplification because it's far easier to block all light by using special black pigment then try to the same effect with C, M and Y mixed together which usually results in muddy brown. Similarly sometimes RGBW is used because it's much easier to get a clean white with a single dedicated light source than mixing it.
Classic teardown! Other very useful parts are the steel shafts from the paper feed path - I remember our late friend Aussie50 tearing a copier down and finding those quite useful.
that model is long discontinued, but when it was new in 2010, is started at $1500 USD for the base unit, and went up from there with multiple paper handling units,,and "finishers" ie collators, binders, etc
Buying a color laser was one of the best decisions ever, am on my third set of toner in 10 years, and there's no drying out if I'm not using it for a few weeks or even months. And it's often cheaper to buy even more expensive replacement parts, since the cost over time is so cheap. (Of course, third party toner is the way to go)
Not to mention scoring a corporate machine like this when you can get a good machine that works again if you just clean it a bit and maybe replace the one part. Might get a full set of toner cartridges to go with it too because the new model is bound to have a "different" model cartridge anyways.
Same here, after multiple crappy inkjets from so called 'reputable brands' I bought a laser printer that has lasted me 4 times as long and with better quality and reliability.
After seeing your photocopier video ages ago, I actually brought a second hand office photocopier for £20 and I am pretty sure I got 10x that value out of it just in motors. Since it was early in my electronics days it was also a tremendous wealth of caps, resistors and wires for prototyping. Was more than worth the money I paid for it.
The mirrors are useful for anyone who plays with lasers as they are good quality front surface reflecting. I have a box of bits from laser printers and old barcode scanners from work which I use bits from for laser light show projects.
I was their age when my dad brought home a junk royal copy machine. My sister and i took it apart on the lawn. We ended up with gear motors, fans, Coronas, chains, fancy lenses, and we got covered in toner. it was the early 80s and toner came in a bottle and didn't stay in the cartridge when we took it apart.
What a grandpa. An engineer and a youtuber. i wish i had a grandpa like you yet i never met my grandpas as they were long gone from this world when i arrived.
I know this sounds bad or like me saying that everyone in Australia is the same but I mean it as a compliment when I say you have the same energy as Steve Erwin one of my childhood heros.
I am a printer repair tech. I could explain how the process works. The printer is not very smart, it doses each print job the same amount of toner. Using sensors, it reads the concentration of toner in the developer and discharges after so many prints. This is depending on how accurate you want your printer to stay. This guy is going good at explaining a printer.
Recently been to a company that makes letter folding machines. Eventhough they are mostly made of metal, it looks similary complex. An amazing piece of engineering
I think I mentioned this under the dublidoo for a cash register teardown, but to me the most amazing enginerding aspect of these devices is the thermals. With a laser printer, you need to put enough heat onto the drum to hold the toner to be transferred to the paper, but dissipate all that heat before the drum is written for the next page...with a resolution of hundreds of DPI and a throughput of several pages per second. All the mechanical enginerding isn't much more impressive to me than an automobile.
There's only a few companies that make the print engines for color laser printers. HP, who, unlike Dell, makes their own laser printers, often uses a print system made by Canon I believe. Typically on these medium sized color printers, after a few years it not economical to repair them as single parts will cost almost as much as an entire new printer. On the printers I've had, usually its the transfer belt that wear out , or a sensor inside that belt path, and those modules run $300-400.
I worked as a laser printer repair tech for 4 years in college.. Every day was replacing bushings, gears, and little sensors broken from paper james... fun stuff.
I recently re-chipped a toner. The original Chip told the printer to stop producing pages. I absolutely detest when I am told by companies to exchange parts even though they still work - just that HP and Samsung etc can make another few cents off you. For a small business it is economical to rechip if you can get another 200 pages or so - maybe not for a huge office building. I will also re-chip the image drum.
Since it is a color printer, all four colors of printing have to precisely align. If the registration is off, then the printed image would look very bad. I am also impressed with the paper handling in today's printers. This device pulls a single sheet of paper out of its drawer, then runs it though a variety of rollers and printing steps. The first computer printers used tractor feed, where sprockets went into holes on both edges of the sheets. But even with all that, manufacturers had trouble making the paper feed correctly.
The lines you get on that stuff Dave, is dirty mirrors. When I was in the Military and a computer, Telephone tech, I had to take printers a part all the time and clean the mirror off and it was good as new.
That laser assembly has a bunch of beautiful first surface mirrors and optics, you can do nice things with them, get two of the scanner motors and a visible light laser (the ones in there are usually IR) you can project lissajous figures
That system board is quite impressive. It's essentially an full-blown computer just to control the printing process. Sadly, it cannot be reused due to it's dedicated nature. @20:42: Is that a SATA connector on the motherboard for a hard disk ? There's also a SODIMM RAM slot, I wonder what's that used for. There's already some RAM on the board itself. That tall metal connector looks like USB, I wonder what's that for ? That "Hard Key" thing ? They're probably using the same motherboard on different printer models, that would explain the presence of unused ports an unpopulated parts.
A printer tech, Dave is NOT lol. Nice rip-apart. 11:00 That is an anti-refill chip. Once X amount of pages have passed through, it doesn't matter how much toner is left, it will show empty. Same if you refill an empty toner cartridge. (You can buy replacement chips from China to indicate a full cartridge so you can refill them yourself)
I would think the light pipe is used to clear the drum between pages (or maybe more periodically). Much like the laser, but over the entire surface evenly.
Gah.... So many times.. The big belt in the middle, is the image belt.. it is charged positive to attract the toner from the image drums. As it passes each drum, it collects the toner of each color and moves it to the large end, where the belt is vertically exposed. The paper never passes the drums, but travels vertically past the end of the belt where the combined toner is then transferred to the paper, just before being pressed and melted by the fuser.
Maybe have a video showing how to make those motors work (the scanning one for instance)? As a hobbyist that have one but with no idea how to make it spin. I would appreciate it.
I used to be dell printer certified, so yes, the repair guy can change that board if it had a fault. Mostly it was cleaning, drum, transfer belt, and fuser replacements
I worked night shift at a NOC for 17 years. Used to fill trash cans all over the office with parts I took off old printers and PCs. Kept all the steppers and steel rods. Sold em by the pound!
I love scrapping old equipment for parts. I try to keep motors and gear trains in tact. Lasers, mirrors and lenses are pretty cool too. All the screws, nuts and other hardware can come in handy as well. Nice find.
If I'm not mistaken, the light from the light pipe likely is use the erase the previous image on the drum or to help the system prepare to clean the residual toner left over. I used to repair copiers many moons ago and have forgotten a lot and I'm sure the technology has improved some as well.
Gears are standardized, so the gear wheels should be readily transferable to other gear trains (once you identify exactly what they are). Even the ABS plastic parts are readily reprocessable if you're into making your own ABS 3D printer filament. The light pipe is probably part of the drum cleaning mechanism. In order to get the residual toner off the drum and erase remnants of the last image, it's bathed in bright light to discharge the residual charge, then scraped clean.
The price of consumables for these things is astronomical . Better to junk an old one and put the repair cost towards something that does the job cheaper.
Apart from the image illumination of the drum by the laser, there is also an erase lamp to delete the image before next cycle. That might have been that light pipe with the diffuser prisms cut into it.
Firstly... that compared to what my company sold before the coof killed our sales... is tiny. We sell proper floor standing MFPs right up to massive industrial printers the size of a mid-sized fishing trawler. Second off... Seing as this is a classic laser machine... you have 2 reasons why the machine will produce lines on the page outside of defects on the document. 1: The charge grid which charges the image drum is possibly contaminated. On some copiers, such as the Sharp MX series, you can clean the charge grids using a special cleaning rod, which has a little wheel on the end of it designed to knock loose toner off the grid(s). It doesn't look like that Dell unit lets you do so though, so that means you'll be swapping out either the charge grids, or the entire PCDU if it's not a serviceable part. 2: As you correctly mentioned, it's possible the photocondictuve drum unit(s) are worn. they have an organic surface and see wear from being constantly electrostatically charged and discharged. This eventually leads to sections of the drum unit losing conductivity, which results in issues with saturation and missing lines / sections of the page. The only way to resolve this is to replace the OPC drum. Although while you're in there it is also worth replacing the charge grids as they tend to corrode from constant electrostatic discharge and toner deposits, which will also affect image quality and usually will cause print quality problems very shortly after replacing the OPC drum. If, however, you are missing lines and/or the image looks feint on the page; > the glass which protects the LSU (Laser scanning unit) and allows the beam through is dirty. If there are toner deposits on this glass, the laser beam(s) which scan across the OPC drum surface can't reach them properly, which causes inconsistencies and outright missing lines. Pretty much all of the laser machines I've ever worked with from the tiny little Sharp MX-C300W right up to behemoths like the MX 6240 or Ricoh C9200 have padded cleaning rods which fit into an orifice where the LSU glass can be cleaned.
I want to see an everyday complex machinery explained by multiple youtubers. EEVBlog - Electronics, Electrics, IC chips, Circuits, Wiring AvE - Motors, Gears, Mechanics, Materials, Manufacturing Technology Connections - History, Breakthroughs, Patents, Mechanisms of every step from start to finish SmarterEveryDay - Speed camera footage on laser and/or toner Tom Scott - Copy prevention, maybe? Any other suggestions on other awesome tech youtubers with unique perspectives? (Please, no generic tech review, no overclocking/RGB modding, no DIY, no destruction. ABSOLUTELY no "life hacks")
Big Clive - cheap electronic gadget teardowns The Signal Path - RF stuff Up and Atom - math and science scanlime - very involved reverse engineering, mostly software Captain Joe, DutchPilotGirl, Mentour Pilot - commercial aircraft and aviation Ms Mad Lemon - retro gaming and audio xraytonyb, glasslinger - retro audio
Sagan & Huxley's reactions were priceless. Worth the teardown by itself. There's another angle though... Learn how it works (future fixes?), in addition to the bonus parts! Especially in the 'States, where we generally suck at recycling, separating out the metal bits from the other bits (especially the plastic) increases the likelihood of the metal being reused. If one is environmentally-conscious, that could be worth the teardown time as well. (Unfortunately, the plastic is likely to end up in a landfill where we are, at present.)
Printer PSUs are good as it is, very useful for 3d printer.It powers motors, heater, MCU, some berry board, displays - everything! You just need 220V bed heater, and triac to drive it in PID is already there. Motors are no good, sadly, for whole lot of reasons. But there are a lot of very useful polished shafts, that could be used as liniar rails and, well, shafts.
15:20 that light pipe is literally a light pipe and those prisms are there so it shines light out of the other side of the pipe and into the same direction probably (in parallel)
It is a reasonably old Dell Laser from 2013, 7 years in service is pretty good. Some data for the nerds at home Service Tag: 4BC26X1 Ship Date: 23 NOV 2013
Correct, removes residual charge from the drum before the wiper removes the toner residue down to the waste path. The drums themselves do not contact the paper directly, they transfer an image to the transfer belt, so that it will build up a colour image as it passes, and finally the paper will be placed in contact with it and charged to transfer the toner across, then right into the fuser.
@@EEVblog The coating on the drum is a photoconductor so the charge is dissipated when light hits it. That's how the latent image is formed on the drum. They used to use selenium, but now they're called "organic photoconductors" I don't know what the photoconductive material is in those. There might be a quenching corona before the lamp too, I can't remember. I guess the lamp just ensures it's completely discharged. A while back, Canon started replacing corona wires with these rubber rollers that contact the drum directly. I think they used a much lower voltage to charge the drum.
Not too sure about these printers, but I know most HP printers are built semi modular, so that they can be fully rebuilt by an engineer on site. But in all my time working with the HP machines, I never saw a single one with that kind of toner leakage. Bearing in mind I was with the NHS, where they are extremely intensive on printing.
The day i found out my school's laser printers used the same SDRAM as my PC was an amazing day. Especially when I found out the printers continued working after I had pinched the RAM!
@13:05 you wrote: "If RGB was used for printing you'd just get a limited range of muddy colors." Now, I am not here to argue or something like that, but just to show you this RGB printer: www.fespa.com/en/news-media/industry/a-true-rgb-printer---lumejet-s200 @15:00 That LED diode with that light pipe is so called LED discharge component which is involved in drum cleaning process. It is used mostly for faster drum recovery. The things you learn everyday... I am printer repairman/service tech, and even I didn't know about this RGB printer before. I found out this maybe 2 months ago.
Sagan is one perceptive kid. And did Huxley say, "floating down a big river and a lava flow?" Q: How does a boy that age know about lava flows? A: Good parenting. Bravo, Davey!
I have a similar printer at home. It's built like a tank and is capable of producing what I'd call photo quality prints. Not sure if mine has edge-to-edge but I think it does. The issue with these older machines is getting working DRIVERS for them. All that tech and engineering expertise but nothing to run it, at least in 64-Bit land.
Was an intern for Lexmark (who made Dell printers for at least a while).
The drums are charged up with a roller, discharged to ground by the laser, then pick up toner electrostatically where still charged. The toner is then transferred electrostatically to the plastic transfer belt, which is later transferred to the paper electrostatically. They use the belt so the colors register with one another; that can't be done well enough by transferring each color to paper independently. Getting the belt to track well on the rollers is quite complicated, and I believe was done mechanically with linkages and springs to steer it passively
Voltages are on the order of 0.8-3kV. The process is very sensitive to environmental conditions (humidity, etc) and paper type.
The engineering effort is tremendous. There is probably an output paperpath team.
I sat in on some meetings where they were doing explicit dynamic FEA (very computation intensive) of the transfer belt because of some issues they were having that required an extremely good model of friction. I collected some data to validate photoconductivity FEA models (among other things).
People maintain tables of the circumference of all of the rollers so if they have a periodic print defect, you can trace back which roller it's coming from.
Lexmark supplied Dell with mono printers. Xerox supplied Dell with colour printers. Not sure if that is still the situation.
@@robertengland8285 I was going to say that kinda looks like a Xerox from how the toner / drums look
Have definitely seen some ultra-high-end production laser presses that don't do the transfer roll dance and do actually deposit the 4 (or more, because spot color toners and MICR and shit) colors independently. IIRC each color even has a separate fuser. Only time I saw it cause trouble with color registration was when we were printing on a plastic substrate that thermally expanded with each fuser pass. But those cost house (or office building) money. And don't fit in dumpsters. Sometimes not even roll-offs.
@@robertengland8285 As a Dell warranty vendor, last I heard, Dell was getting out of the printer business and instead selling printers from various brands bundled in online after the sale. I think Dell officially quit all imagining product sales in 2018. And YES that is a Xerox OEM. And as of today, Lexmark also used Xerox as an a3(11x17) OEM.
Loved the “that’s just a roller that rolls” comment in the video. That is a high voltage transfer roller and probably the cause of all the lines on the prints.
The light pipe is an erase lamp to help clear the latent image from the drums.
Liked this video. Reminds me of days when I used to have to train engineers on servicing these. I was a trainer for Lexmark, Xerox, HP, Canon and Epson in the past, as well as IBM, Fujitsu, Ricoh and Hitachi huge high speed printers that connect to mainframes. Amazing really that from the smallest printer up to the 2000+ feet per minute continuous machines the tech, fused aside, was essentially the same.
I started working on these back in 1981 ... I'm studied electronics tech in college ( EET ) shortly after returning from Sydney, Australia (2 years LDS Mission) I answered a help wanted ad and have doing it ever since. Started my own copier printer business 28 years ago and am pretty much retired now. I started with black and white liquid toned copiers, then went on to dry toned machines, then machines with Document feeders and sorters, then came Fax machines ... Roll coated paper, then plain paper, then scanning. as technology moved forward ... the amount and size of parts shrank, motors were driven both directions and one way clutches enabled one motor to have 2 functions, magnetic clutches and one way clutches brought down the part count ... the electronic complexity increased exponentially. Customers used to use a Copier, a Fax Machine, a Printer, and a Scanner ... then someone thought to combine them all into one unit !! the only problem with that was that a simple paper jam brought the whole office down.
It's been an interesting career and I've always said that someday I'll write a book about it !! As a side note ... many of these machines aren't even made by the people whose name is on the front ... same goes for most consumer electronics. The parts are sourced from all over the world and parts from one machine sometimes were the same as another machine, ex: Canon built HP printers, Lexmark used to be Toshiba, Dell was made by Lexmark. who got the machine from Toshiba ... Savin, Gestetner, Nashuatec are all built by Ricoh. Xerox hasn't built anything for years, they have put their name on machines from Sharp, Toshiba and Samsung ... As I hear it in the industry, HP bought Samsung's printer business, Xerox has tried to buy HP ....... the reason toner is expensive is because of the chip that the manufactures put on the cartridge, trying to keep you from using third part Ink / Toner ... HP used the same black toner from the old HP2's for many. many years ! ( It's been an interesting ride )
I get a kick out of how excited you get over an old copier or printer ... I watch a lot of your videos ... interesting to see what makes something work ... everything we use today started out with a copier that relied on a big motor, chains, gears, relays, micro switches, Heat lamps and Semi-conductive image drums.
Keep up the good work ... enjoy your videos !! Mike
Worked for Samsung, can confirm the printer line was sold to HP
My Journey in that game was started in 1989. You did very well, I appear to have been going in reverse in comparison. Well done though 😀
The people that design highly complex machines like that, are geniuses.
I always found it funny that people get so impressed seeing a 3d printer work, while it only has 3 stepper motors and a heated extruder in it. At the same time, these people own laser printers themselves and are mostly pissed at how crappy their printers are.
Laser printers hide the complexity, and are so good that people forget exactly how complex it actually is, till it has an issue. If somebody made a transparent case laser to show how it all goes together (hard, seeing just how many parts of the process are light sensitive, and how many optical sensors there are in there) you would be impressed.
Then show them the operation of an offset printer, where it is all out in the open and is all "no touchee or losie fingery" and they think that is complex. Digital plate printer is 1000 times as complex, but is all covered, and costs $30 million, but you only press a few buttons and it does it all by itself. It does not look as impressive, even if it covers 30m of floor and is 5m wide. Roll in one side, finished sheets out the other side. Visited our one printer, and got the tour. Hearing protection not optional.
despite the simplicity, some 3D printer companies find a way to screw i
That was me when i heard about 3d printers. Then i saw one. " oh its a cnc machine with a glue gun on it"
Printers are just a special level of Hell all by themselves without even adding a 3rd dimension.
Jon If you intentionally cut off the end of this comment, well played
The light pipe at 15:10 is used to erase the previous residual image before the next image is scanned onto the drum via the laser.
That is odd, erase lamps pretty much disappeared when PCRs came along. I wonder why Lexmark brought them back?
@@RavenWolfRetroTech I think you've made a false assumption. This could be a pretty old device, or at least an old engine design. As Dave kept pointing out, there's a HUGE amount of engineering that went into the print engine's mechanical design, so Xerox (as the engine OEM has been identified as) would want to use that engine design in as many models as possible to get the most value out of the design. That device might be over 20 years old (actually having a Centronics port suggests it's a vintage model, although interfaces are generally cheap bolt-ons for modern devices), and the engine design might well be 30.
@@evensgrey That may be so and considering my expertise is in Canon based engines like HP and larger equipment, particularly Ricoh, it may be a manufacturer idiosyncrasy. That printer looks a LOT like a Hitachi design but I'm pretty certain that all Dells were Lexmark. Being that it is color and uses an intermediate transfer belt, I would not think it could be older than 2004ish. I am certain they would not put that there without a reason so it makes me curious as to why? I generally deal with much older printers these days but, in general, blank lamps were used to erase the remaining drum charge on corona wire based systems since the corona is additive and you would get ghost images. A PCR is in physical contact with the drum so it levels the charge on its own while using about 10-15% of the power needed for a corona. @peter Paolucci is absolutely correct what that is for but I am curious why it was needed
@@RavenWolfRetroTech Xerox still use erase lamps in their in-house designed image transfer units.
@@cambridgemart2075 That is interesting, any idea why? It also interesting how much designs vary from manufacturer to manufacturer.
High voltage board salvage the high voltage resistors out of there, as they are useful to build a DIY high voltage probe, using the 2kv rated resistors.
Yep, good idea, I've done a video on HV probe design with Doug Ford
@@EEVblog Is there enough to do a low cost 100-to-1, 1KV at 500khz? Nice idea for a cheap SMPS probe vid.. (safety of course with some disclaimers..)
@@EEVblog Great video idea indeed. Is there a chance to do something like this? Obv with disclaimers as stated. A simple HV probe setup for the home user would be petty nifty. Obviously not a replacement (or could be?) for a proper set like the EEVblog set.
@@CliveChamberlain946 Depends on the printer, but with a colour laser you will have at least 6 different HV sources in the unit, a regular mono laser 3, as one for the drum, one for the transfer roller and one for the pre charge on the drum.
You will need to look for the AC pre transfer to see the capacitor value they use for compensation, as that is the only one that is AC signal, the rest are all DC. Only one without a big ceramic capacitor though, and generally a separate black potted unit.
I got one of those boards from a laser printer and laser figured be cool project parts.
The disadvantage of parting out such a thing is that you are left with 5 times as much trash as you started with!
You get the couple of parts that are interesting and put them in the parts boxes but now you have a car trunk full of trash to haul away to the recycling center :-(
Output paper path guy is not happy you called him a team.
He should be. He does a whole team's work on his own and it shows
He eats enough Twinkies for a team!
I was a repair guy on the Dell 5100CN printers. and i still use one, those toner cartridges, i got about 30 news ones. those printers will print edge to edge on both sides at about 2 seconds per page. to bad you trashed it, a clean up and those lines would have gone away.
Yeah, but sacrificed for the greater good.
I found it very interesting and doubt that once you have seen inside the laser scanning mechanism you could get it all back together without spending more than a month! Yeah it wasn't really trashed, have you seen some channels where they literally take a baseball bat to new gear just for views? Companies, retail or whatever regularly chuck gear when their leases expire or auction it off, keep your eyes open for an opportunity of a business shutting up shop and I am sure you will be able to get a free laser printer.
@@EEVblog DAVE DOESN'T KNOW HOW TO FIX ANYTHING---HE ONLY DESTROYS.
Why did the main board have a SATA connector?
LeviHB caching on hdds. Seen this on big HP printers too.
The mechanical parts were designed by Cogswell Cogs, in competition with Spacely Sprockets.
And driven by Flintstone Firmware.
22:28 those gears with the helical ramps; the ramps are slipper clutches. Since steppers are known for producing large amounts of torque, you need a passive means of torque limiting so they don't strip the gears if there is a jam. There is likely springs that push on one side of the gears to provide preload on the helix and give the right amount of overload tension. The helix angle will match the helical gear angle so it cams out at the same gear timing angle so there is no advance or retard as it cams out.
This is why youtube comments are still worth wading through :-)
The angle would not be the same if you want to use it as an overload clutch as there would be opposing force that kept it in place. However the ramp angle is very shallow so it will climb that against any kind of helix angle. The timing will suffer but I think this may have been to drive the toner fill or recovery augers so timing does not matter. The printer would detect the slip in some way and decide the auger was stuck due to toner recovery bin too full or if it stirred first one way against the shoulder to mix the supply and then turned against the ramp to level and detect the toner. The designers have a whole book of sneaky tricks that they use to do two functions with one part or sensor.
I was thinking the were there to allow for manual clearing of paper jams, enabling the output path rollers to turn independent of the drive motor / gearing.
I think that in this case, they are simply one way clutches, to allow paper jam clearing by pulling it out in the forward direction.
I remember the first laser printer I ripped apart for the stepper motor parts, that was when I was first getting into tinkering with electronics! Now I have a closet full of them.... and I had to get shelves to hold all the small form-factor PCs... I can stop anytime I want though!
I'm the same with valves, a... a friend tells me
I'm a wood, metal, scrap and brass collector of 7 + years. My mum and grandpa collected. Now I only have 2 square metres left in my bedroom. I need a skip bin for my next birthday.
"No, really usable parts.." in the laser unit? Dave, these surface mirrors are one of the best parts in that printer.
Well they would be useful to someone who does lots of experiments with lasers but Dave never messes around with lasers so no use to him.
They're also good if you want to make a really high quality kaleidoscope. Better mirrors mean the repeated images go "off to infinity" to the sides much further before they become dark or distorted.
Plus all the lenses and that raster scanning motor/prism unit!
He doesn't know what he's talking about. Clueless
@@ian-c.01 macro reps lol
Printer tech and trainer from Xerox here, that black linkage @08:00 is a mechanism to disconnect the drive of the colour drums. The colour drums are not driven during B/W printing, extending the life of the drums a bit.
The toner supply is controlled with a toner concentration sensor in the drum / developer cartridge. If the sensor sees that there is little toner in the developer, the stepper motors of the cartridges are turned on for a few seconds (2 seconds for this machine). The fresh toner is dispensed in the developer, and mixed in with the developer material.
The plastic rod and LED are part of the drum eraser system, It makes the drum electrically neutral and erases the electrostatic residue of the drum. The green stuff on the drum is a photo sensitive layer, so getting rid of electrostatic charge is easy, just shine a light on it.
If you have any other questions, let me know
I like how you put the blue tarp out like you're dismembering a body.
The blue tarp is for bodies.. He does that off camera of course XD
@@vladimir7838 Blue tarp because the toners go all over. Absolute murder to get out of carpet, and as he is renting this area he does not want that charge at end of lease in 3 months. Black is easy to hide, you just do 3 passes with a wet extractor and cold water, with first carpet cleaning detergent, second liquid fabric softener and third with plain water, and it will be almost totally gone from sight. the colours though will still be visible, as they stand out from the dirt. If you still see black in the third pass do the cycle again, but in general when you do the rinse the water will be pale brown.
@@vladimir7838 No no, the red one is for bodies. Blue for printers.
And then goes barefoot
@@liebherr11602 He doesn't want to get his shoes full of toner/blood.
"Thank you for repairing the printer. You have golden hands.
"
"My hands are CMYK at the moment."
Yep, but if the Vacuum cleaner develops a leak, you and the whole office are 3 shades darker than when you started that morning, that happened to me once, noticed and shut down the vacuum cleaner … it was bit hazy ..
FYI on cleaning all that horrid toner powder off your hands - use cold water and lots of soap. Hot water will start the setting process and make it harder to clean off :-)
Honestly, I'd have used a few cents pair of nitrile gloves before taking everything apart just to avoid the hassle :)
Your water will have to be hotter that 100 deg C. Fuser surfaces runs between 150 an 200 deg C. Does not stop that fine powder from getting trapped in the clothing fiber. If you ever get a toner spill on the floor use a dry cloth or paper towels. a 3M toner vac would be the right thing. You need some real nasty chemicals to desolve it like paint thinners Always wear black...
@@Allan-mf1he Hi Allan. I'm just passing on words of wisdom from an old HP copier tech. He told me that hot water wont set the toner, but it makes it harder to remove. Still prefer Gnomish's suggestion of avoiding it at the start.
@@paulp2089 True avoiding it would be best. Toner over the years also changed quite a bit, its much safer and polymerized vs pulverized making the particles smoother and more uniform in size. Lots of technology going into toner. There is no getting around toner for me working on production machines i look like a miner at the end of the day:).
Take care if you have to vacuum up a big toner spill. The powder has an electrostatic charge to allow it to be picked up by the high voltages. if you suck it up in a vac with a metal nozzle you can make inch-long sparks, normally to your nose when you are looking in the machine. Its the kind of experience you remember. ;-)
Those gears with the ramps obviously allow travel in one direction only so perhaps they allow you to pull the paper out without breaking the geartrain.
Yes the are for what are called relay rollers once the paper have gone from one set of rollers to the next the previous drive can switch of and roll free in the feed direction so the roller set upstream can pull it freely.
These things were $1549 (US) brand new. That was ten years ago though, so I suppose the company probably got their money's worth out of it.
RGB adds up to white. CMY adds up to black.
if you shine torches with filters onto a wall it shows up additive vs subtractive color easily. It's very interesting for the history of color photography and darkroom printing processes (before this ink and toner based plotters did it better and faster).
And you can really use a colour gamaut diagram to choose any colours you want to be primary colours, as long as they span the colours you wish to produce.
Like to see it as the difference between projected and reflected light.
6:24 give Dave some privacy, he wants to be alone with his motor
Feeler vision.
That printer is from the 26th of August 2013. I would expect it to be in service for much longer than 6-7 years. Guess someone needed an upgrade
Probably just started to play up and they didn't bother to get it fixed.
They are so cheap nowadays that you just throw it out when the lines start appearing. Anything older than 5 years is going to have been written off and thus has no value left for the company beancounters.
@@benbaselet2026 This one was $2000 aud though
These are stellar for fabricators, too, not only electronics people. Especially the multitude of high quality shafts, those things are priceless.
"Whats worse than a paper jam?"
"Falling off a cliff"
"Being sucked into a black hole"
Cant argue with that :)
especially from a what 5y/o?
If you're the guy who's tasked with unjamming said printer being sucked into a black hole can be synonymous with said task.
I think that light pipe is a quenching lamp. It just eliminates any residual charge on the drum. The older ones used fluorescent tubes
Mmm mmm, lots of stepper motor goodness. The engineering in these devices is amazing. I always wonder how many model iterations there are over the years using the same "guts", with cosmetic changes.
Quite a few, they tend to change cosmetic parts, and then after a few years change back to the older one, but with a slightly redesigned cartridge, so the old ones are no longer usable.
Having looked at some of the (nowadays pretty much utter garbage) "different" models of printers HP has made over the last 15 years... too many.
and the microchips don't actually monitor physical toner level, they are simply eeprom devices that register if the toner was used, and decrements the "full" to "empty" count. You'd be surprised how much toner actually remains in an "empty" cartridge.
- The image is formed on the transfer belt (9:15) by the individual drums. The printer will occasionally print test patterns on the belt for color synchronization and density correction and scan them with sensors without ever needing to actually print them on paper. You won't know this is happening unless you open the door at the right time in the warmup cycle and see the patterns on the belt.
- The paper only ever goes up the right side of the machine and comes out the top. The roller at 8:53 presses paper against the transfer belt at the edge and immediately sends it up the fuser. Or in the case of double sided prints will send the paper around through all that extra plastic in the door to print on the back side.
- LED and light channel connected to them are for erasing the drums. They are quite effective and are still widely used in copiers and printers today. Actually, They are used along with the corona charge wires (buried in the drum assembly) to make sure that all areas of the drum are being charged and discharged regularly, not just where the printed areas of the page land.
- Many of those 4 pin connectors are only for tracking new consumable items like drums and transfer belt. They connect to a "fuse chip" that blow after the printer acknowledges that a new item has been installed. It will reset the page counter for that item then command the chip to blow. Many would think this is a money-making technique, which it sort-of is as you cannot take that item out and install in another printer and have it think it's new. But more importantly the machine will compensate for gradual wear by adjusting voltages etc. which you want reset when you install new items. The Transfer Belt has one of these chips on the back side as seen in 9:39.
I do service on these style machines as well as color photocopiers (not dells/lexmarks)
@ 22:40 : nope Dave, except if it's wrote on, it's not an average DC motor but a 3-phased motor (like spinning motor from disk burner/reader or HDD)
One of my engineer friends say that's accurate enough for know position (and that's why it's used in these devices)
But still keep it (with the power supply board come from printer, high probability that's got +5V/+12V also)
I'm just glad that I'm not the only one with a bin of scrapped PCB's and another bin of scrapped motors, power supplies, connectors, etc.
That big flat belt that wouldn't come out at 9:11 is the image tranfer belt. You have to lift the blue handles to pull it out all the way. What happens is each of the 4 drums lays down the different color images onto the belt. When the image is complete, then the belt makes another rotation as the paper passes under it, thereby transferring the image from the belt onto the paper. That is why it is called the transfer belt. This makes the giant printer slow because the belt has to make 2 passes for the image to end up on the paper. So the unwanted line could come from this belt also because there is a cleaning blade that cleans the belt. If the belt is not clean, then you end up with ghost image from the previous print or lines. Drums and fuser roller (heat rollers) can introduce lines too. The more modern color printers deposits the toner straight from the drum to the paper which makes it faster and reduce one less source that can introduce a line on the print!
The light pipe at 15:16 is for discharging the drum. It effectively erases the drum so that it is ready to receive another image from the laser.
Often when someone worked on a color printer, they end up with psychedelic boogers because they breathed in some of the color toner! 😂
The big brown belt is the transfer belt. The image is built up on it by static from each of the 4 drums. then the foam transfer roller statically charges the paper to transfer the image to the paper. Finally the fuser melts the toner into the paper
Also a great source of 4mm screws (unfortunately only a few nuts).
If you buy a box of 4mm nuts these screws can be used for Meccano screws.
I’ve got a box of metric screws from tearing apart printers and copiers, being self employed and re-manufacturing for machines to sell I would buy machines wholesale and “Borg’ify” to get a good unit to sell, also had the toner stained fingers and cuticles !!! Now retired, my hands look normal except from the scars of injuries: shocked, crushed, cut, etc.
These lightstrips are so called pre conditioning exposure light to clear the drums electrostatic charge after a rotation. If this led fails, there could be an image offset of the previous image on the drum. By exposing the drum with light across the full width of the drum whilst rotating, the photoconductive layer starts to conduct and residual static electricity will flow to ground, thereby clearing the charge from the drum. After this the drum is ready for the "new" charge.
Corona wires are used less often. Instead transferrollers and primary charging rollers are more common nowadays. Their made of conductive rubber and create a more evenly charge across the drums and paper. Improving image quality and producing less ozone gas.
Have a great day,
A former Canon techie from Holland.
I have done this for years and have a shed full of parts that eventually will end up in the dumpster...totally worth the time and effort. Cheap thrills!
Front surface mirrors are good for kaleidoscopes.
I saved a Dell 4C laser printer from being trashed by my company just because it refused to work with a message saying that the belt's official lifetime was exceeded (100,004 pages printed!). I was not going to accept that. Took me some studying of the really excellent service documentation (it turned out the printer was really a rebranded Xerox) to find that there were two signals going to the drum that were called SDA and SCK - without further explanation what the obvious I²C was used for. :) I then only needed to reprogram the drum's lifetime value in its EEPROM - and the printer booted up fine, and the printing quality is still amazing! These business printers are really a gem of engineering and documentation. Hats off!
As a kid we would go to the dumps with a cardboard box and wire cutters, remove the resistors and capacitors from TV sets. I still have some of those parts laying around somewhere. You run out of room storing junk.
My Brother HL=2140 has been really reliable too. It is only a black and white laser I must have had for more than 7 or 8 years but it has never given me any trouble, other than just ONE paper jam. I have only replaced the toner twice and one of those was that underfilled starter cartridge a lot of printers sometimes come with. It never needed a new drum and still prints like the day we first brought it home. One time I had a problem with dirty looking prints but that was easily fixed by separating the drum and toner cartridges. All I had to do was take it outside and carefully blow the loose toner out of the drum assembly. Now it prints like new again. I once had an Epson Stylus color 200 but that thing kept getting clogged nozzles and wanting new cartridges much too soon. I threw it away!! It is a shame too because it printed much better photos than some of those dedicated photo printers. I had a portable photo printer and it didn't print as sharply and nicely as the Epson did. Still though, I was tired of inkjets and threw the thing away. I never had a printer that was so unreliable. Laser printers are the way to go. Sometimes they can be very expensive but hopefully those ones will last longer than you.
you will spend as much time cleaning up as you did taking it apart. Thanks Dave, and those of you who left comments, it was fun to read.
What's worse than a paper jam?
A paper cut!
The correct terms are additive and subtractive colour systems. They are complementary in every respect, if you add R and B you get C, if you add G and R you get Y, if you add R and B you get M. Similarly if you substract M and C from W you get B, Y and C from W you get G, and for Y and M from W you get R. K is only there for simplification because it's far easier to block all light by using special black pigment then try to the same effect with C, M and Y mixed together which usually results in muddy brown. Similarly sometimes RGBW is used because it's much easier to get a clean white with a single dedicated light source than mixing it.
Classic teardown! Other very useful parts are the steel shafts from the paper feed path - I remember our late friend Aussie50 tearing a copier down and finding those quite useful.
9:57"...mold afficionados..."!!! SUBSCRIBED!!!
I collect spores, mold, and fungi.
@@EEVblog I thought it was a joke. The only thing I seem to collect is dust😞...and fauxpas.
@@EEVblog I had heard you were a fun guy but I had no idea they were referring to your mold collection. ;-)
that model is long discontinued, but when it was new in 2010, is started at $1500 USD for the base unit, and went up from there with multiple paper handling units,,and "finishers" ie collators, binders, etc
Thanks for the insight That start price isn't too bad ... ( Unless you missed a " 0 "
Buying a color laser was one of the best decisions ever, am on my third set of toner in 10 years, and there's no drying out if I'm not using it for a few weeks or even months. And it's often cheaper to buy even more expensive replacement parts, since the cost over time is so cheap. (Of course, third party toner is the way to go)
Not to mention scoring a corporate machine like this when you can get a good machine that works again if you just clean it a bit and maybe replace the one part. Might get a full set of toner cartridges to go with it too because the new model is bound to have a "different" model cartridge anyways.
Same here, after multiple crappy inkjets from so called 'reputable brands' I bought a laser printer that has lasted me 4 times as long and with better quality and reliability.
My guess is that the clear plastic tubes next to the drums are a light pipe routing UV from LEDs to erase the drums prior to receiving a new image.
After seeing your photocopier video ages ago, I actually brought a second hand office photocopier for £20 and I am pretty sure I got 10x that value out of it just in motors. Since it was early in my electronics days it was also a tremendous wealth of caps, resistors and wires for prototyping. Was more than worth the money I paid for it.
I was a copier repair guy back in the mid 90s.. To this day I still have parts from the copier graveyard in the warehouse! I wish I had taken more.
The mirrors are useful for anyone who plays with lasers as they are good quality front surface reflecting. I have a box of bits from laser printers and old barcode scanners from work which I use bits from for laser light show projects.
You're the only youtube channel that could ever make anyone physically want a dumpster room
You don't go to the youtubes much do you?
I was their age when my dad brought home a junk royal copy machine. My sister and i took it apart on the lawn. We ended up with gear motors, fans, Coronas, chains, fancy lenses, and we got covered in toner. it was the early 80s and toner came in a bottle and didn't stay in the cartridge when we took it apart.
What a grandpa. An engineer and a youtuber. i wish i had a grandpa like you yet i never met my grandpas as they were long gone from this world when i arrived.
I know this sounds bad or like me saying that everyone in Australia is the same but I mean it as a compliment when I say you have the same energy as Steve Erwin one of my childhood heros.
I am a printer repair tech. I could explain how the process works. The printer is not very smart, it doses each print job the same amount of toner. Using sensors, it reads the concentration of toner in the developer and discharges after so many prints. This is depending on how accurate you want your printer to stay. This guy is going good at explaining a printer.
Recently been to a company that makes letter folding machines. Eventhough they are mostly made of metal, it looks similary complex. An amazing piece of engineering
I think I mentioned this under the dublidoo for a cash register teardown, but to me the most amazing enginerding aspect of these devices is the thermals. With a laser printer, you need to put enough heat onto the drum to hold the toner to be transferred to the paper, but dissipate all that heat before the drum is written for the next page...with a resolution of hundreds of DPI and a throughput of several pages per second. All the mechanical enginerding isn't much more impressive to me than an automobile.
There's only a few companies that make the print engines for color laser printers. HP, who, unlike Dell, makes their own laser printers, often uses a print system made by Canon I believe. Typically on these medium sized color printers, after a few years it not economical to repair them as single parts will cost almost as much as an entire new printer. On the printers I've had, usually its the transfer belt that wear out , or a sensor inside that belt path, and those modules run $300-400.
Not all HP laser printers were HP, some were made for them by Lexmark.
I worked as a laser printer repair tech for 4 years in college.. Every day was replacing bushings, gears, and little sensors broken from paper james... fun stuff.
I recently re-chipped a toner. The original Chip told the printer to stop producing pages. I absolutely detest when I am told by companies to exchange parts even though they still work - just that HP and Samsung etc can make another few cents off you. For a small business it is economical to rechip if you can get another 200 pages or so - maybe not for a huge office building.
I will also re-chip the image drum.
You're like the Steve Irwin of electronics it's great, you get so excited about everything
That switch at the back is an interlock for the rear cover. Will throw a ros fault code if its not actuated
Since it is a color printer, all four colors of printing have to precisely align. If the registration is off, then the printed image would look very bad. I am also impressed with the paper handling in today's printers. This device pulls a single sheet of paper out of its drawer, then runs it though a variety of rollers and printing steps. The first computer printers used tractor feed, where sprockets went into holes on both edges of the sheets. But even with all that, manufacturers had trouble making the paper feed correctly.
Love it! Already as a kid i had a look inside electronics peopled throwed away. Always fascinating!
Thanks for your professional look inside!
The lines you get on that stuff Dave, is dirty mirrors. When I was in the Military and a computer, Telephone tech, I had to take printers a part all the time and clean the mirror off and it was good as new.
That laser assembly has a bunch of beautiful first surface mirrors and optics, you can do nice things with them, get two of the scanner motors and a visible light laser (the ones in there are usually IR) you can project lissajous figures
The front-surface mirrors are aluminium and easily damaged by fingerprints.
The ridges on the light pipe direct some light down and out of the pipe. Much like a lenticular grid or Fresnel lens.
That system board is quite impressive. It's essentially an full-blown computer just to control the printing process. Sadly, it cannot be reused due to it's dedicated nature.
@20:42: Is that a SATA connector on the motherboard for a hard disk ? There's also a SODIMM RAM slot, I wonder what's that used for. There's already some RAM on the board itself.
That tall metal connector looks like USB, I wonder what's that for ? That "Hard Key" thing ?
They're probably using the same motherboard on different printer models, that would explain the presence of unused ports an unpopulated parts.
A printer tech, Dave is NOT lol. Nice rip-apart.
11:00 That is an anti-refill chip. Once X amount of pages have passed through, it doesn't matter how much toner is left, it will show empty. Same if you refill an empty toner cartridge. (You can buy replacement chips from China to indicate a full cartridge so you can refill them yourself)
I won't give up my day job
@@EEVblog I'm glad....I LOVE your day job! Keep up the great content! I love the dumpster finds!
I would think the light pipe is used to clear the drum between pages (or maybe more periodically). Much like the laser, but over the entire surface evenly.
Honestly, I would keep the PSU as it is. I usually keep them (especially smaller ones). You never know when you'll need a multiple output PSU!
Gah.... So many times.. The big belt in the middle, is the image belt.. it is charged positive to attract the toner from the image drums. As it passes each drum, it collects the toner of each color and moves it to the large end, where the belt is vertically exposed. The paper never passes the drums, but travels vertically past the end of the belt where the combined toner is then transferred to the paper, just before being pressed and melted by the fuser.
Maybe have a video showing how to make those motors work (the scanning one for instance)? As a hobbyist that have one but with no idea how to make it spin. I would appreciate it.
The complexity of this thing is insane....I have a new respect for printers
I used to be dell printer certified, so yes, the repair guy can change that board if it had a fault. Mostly it was cleaning, drum, transfer belt, and fuser replacements
I worked night shift at a NOC for 17 years. Used to fill trash cans all over the office with parts I took off old printers and PCs. Kept all the steppers and steel rods. Sold em by the pound!
Cute boys, “a thousand or more”. It is incredible how much volume was stuffed into the case of that printer.
I love scrapping old equipment for parts. I try to keep motors and gear trains in tact. Lasers, mirrors and lenses are pretty cool too. All the screws, nuts and other hardware can come in handy as well. Nice find.
If I'm not mistaken, the light from the light pipe likely is use the erase the previous image on the drum or to help the system prepare to clean the residual toner left over. I used to repair copiers many moons ago and have forgotten a lot and I'm sure the technology has improved some as well.
Gears are standardized, so the gear wheels should be readily transferable to other gear trains (once you identify exactly what they are).
Even the ABS plastic parts are readily reprocessable if you're into making your own ABS 3D printer filament.
The light pipe is probably part of the drum cleaning mechanism. In order to get the residual toner off the drum and erase remnants of the last image, it's bathed in bright light to discharge the residual charge, then scraped clean.
This is where the product proves to be more than the sum of its parts.
The price of consumables for these things is astronomical . Better to junk an old one and put the repair cost towards something
that does the job cheaper.
Apart from the image illumination of the drum by the laser, there is also an erase lamp to delete the image before next cycle. That might have been that light pipe with the diffuser prisms cut into it.
Firstly... that compared to what my company sold before the coof killed our sales... is tiny. We sell proper floor standing MFPs right up to massive industrial printers the size of a mid-sized fishing trawler.
Second off... Seing as this is a classic laser machine... you have 2 reasons why the machine will produce lines on the page outside of defects on the document.
1: The charge grid which charges the image drum is possibly contaminated. On some copiers, such as the Sharp MX series, you can clean the charge grids using a special cleaning rod, which has a little wheel on the end of it designed to knock loose toner off the grid(s). It doesn't look like that Dell unit lets you do so though, so that means you'll be swapping out either the charge grids, or the entire PCDU if it's not a serviceable part.
2: As you correctly mentioned, it's possible the photocondictuve drum unit(s) are worn. they have an organic surface and see wear from being constantly electrostatically charged and discharged. This eventually leads to sections of the drum unit losing conductivity, which results in issues with saturation and missing lines / sections of the page. The only way to resolve this is to replace the OPC drum. Although while you're in there it is also worth replacing the charge grids as they tend to corrode from constant electrostatic discharge and toner deposits, which will also affect image quality and usually will cause print quality problems very shortly after replacing the OPC drum.
If, however, you are missing lines and/or the image looks feint on the page;
> the glass which protects the LSU (Laser scanning unit) and allows the beam through is dirty. If there are toner deposits on this glass, the laser beam(s) which scan across the OPC drum surface can't reach them properly, which causes inconsistencies and outright missing lines. Pretty much all of the laser machines I've ever worked with from the tiny little Sharp MX-C300W right up to behemoths like the MX 6240 or Ricoh C9200 have padded cleaning rods which fit into an orifice where the LSU glass can be cleaned.
We used to have one of these printers in my office. Great for printing training material and manuals. I sure do miss it now!
I want to see an everyday complex machinery explained by multiple youtubers.
EEVBlog - Electronics, Electrics, IC chips, Circuits, Wiring
AvE - Motors, Gears, Mechanics, Materials, Manufacturing
Technology Connections - History, Breakthroughs, Patents, Mechanisms of every step from start to finish
SmarterEveryDay - Speed camera footage on laser and/or toner
Tom Scott - Copy prevention, maybe?
Any other suggestions on other awesome tech youtubers with unique perspectives?
(Please, no generic tech review, no overclocking/RGB modding, no DIY, no destruction. ABSOLUTELY no "life hacks")
Big Clive - cheap electronic gadget teardowns
The Signal Path - RF stuff
Up and Atom - math and science
scanlime - very involved reverse engineering, mostly software
Captain Joe, DutchPilotGirl, Mentour Pilot - commercial aircraft and aviation
Ms Mad Lemon - retro gaming and audio
xraytonyb, glasslinger - retro audio
Hux is really energetic! Knock of the ole block I'd say.. soon to be seen with Dad on the next canyon run?
Sagan & Huxley's reactions were priceless. Worth the teardown by itself. There's another angle though... Learn how it works (future fixes?), in addition to the bonus parts! Especially in the 'States, where we generally suck at recycling, separating out the metal bits from the other bits (especially the plastic) increases the likelihood of the metal being reused. If one is environmentally-conscious, that could be worth the teardown time as well. (Unfortunately, the plastic is likely to end up in a landfill where we are, at present.)
hey, color 101. light colors add to white, toner colors add to black.
Printer PSUs are good as it is, very useful for 3d printer.It powers motors, heater, MCU, some berry board, displays - everything! You just need 220V bed heater, and triac to drive it in PID is already there. Motors are no good, sadly, for whole lot of reasons. But there are a lot of very useful polished shafts, that could be used as liniar rails and, well, shafts.
15:20 that light pipe is literally a light pipe and those prisms are there so it shines light out of the other side of the pipe and into the same direction probably (in parallel)
If you have a lathe, these things are full of nice machinable rod.
O yea, mostly 6, 8 and 10 mm shafts they are magnetic but does not rust. Good from making small CNC machines!
Yep, precision ground and accurate. Usually bang-on for dimension when I mic it. Would cost you a fortune if you needed to buy it
It is a reasonably old Dell Laser from 2013, 7 years in service is pretty good.
Some data for the nerds at home
Service Tag: 4BC26X1
Ship Date: 23 NOV 2013
Can you do a video on hacking lcd panels from different devices?
Maybe the LED with the long rippled light pipe is for erasing residue charges on the drums after each pixel line?
Correct, removes residual charge from the drum before the wiper removes the toner residue down to the waste path. The drums themselves do not contact the paper directly, they transfer an image to the transfer belt, so that it will build up a colour image as it passes, and finally the paper will be placed in contact with it and charged to transfer the toner across, then right into the fuser.
@@SeanBZA How does light remove static charge? I thought a 2nd corona wire did that?
@Svein Are Karlsen There has got to be a dodgy Kickstarter idea in that...
@@EEVblog The coating on the drum is a photoconductor so the charge is dissipated when light hits it. That's how the latent image is formed on the drum. They used to use selenium, but now they're called "organic photoconductors" I don't know what the photoconductive material is in those.
There might be a quenching corona before the lamp too, I can't remember. I guess the lamp just ensures it's completely discharged. A while back, Canon started replacing corona wires with these rubber rollers that contact the drum directly. I think they used a much lower voltage to charge the drum.
@@EEVblog Same way the imaging laser does it spot-wise, the drum is a photosensitive semiconductor.
Not too sure about these printers, but I know most HP printers are built semi modular, so that they can be fully rebuilt by an engineer on site. But in all my time working with the HP machines, I never saw a single one with that kind of toner leakage. Bearing in mind I was with the NHS, where they are extremely intensive on printing.
The day i found out my school's laser printers used the same SDRAM as my PC was an amazing day. Especially when I found out the printers continued working after I had pinched the RAM!
23:53 there is description of the connector so it’s easy to use it. Usually it’s step/dir drive.
@13:05 you wrote: "If RGB was used for printing you'd just get a limited range of muddy colors."
Now, I am not here to argue or something like that, but just to show you this RGB printer: www.fespa.com/en/news-media/industry/a-true-rgb-printer---lumejet-s200
@15:00 That LED diode with that light pipe is so called LED discharge component which is involved in drum cleaning process. It is used mostly for faster drum recovery.
The things you learn everyday... I am printer repairman/service tech, and even I didn't know about this RGB printer before. I found out this maybe 2 months ago.
Demo the laser box with a hand held laser pointer and some talcom powder
Possible!
Sagan is one perceptive kid. And did Huxley say, "floating down a big river and a lava flow?" Q: How does a boy that age know about lava flows? A: Good parenting.
Bravo, Davey!
I have a similar printer at home. It's built like a tank and is capable of producing what I'd call photo quality prints. Not sure if mine has edge-to-edge but I think it does.
The issue with these older machines is getting working DRIVERS for them. All that tech and engineering expertise but nothing to run it, at least in 64-Bit land.