There is enough space to drill multiple holes without breaking traces. I'd drill some holes on both ends of the crack and then use cable ties to tie them together. That should give it enough mechanical strength to last the ages, in combinaties with the wires that prevent electronical failures. A technique that I have used in the past on a CRT with a crack was to remove solder mask from broken traces and solder a paper clip over the strace, completely covering it with solder tin. The paper clip provides mechanical strength, while the solder tin takes care of conductivity.
Well, in the case of this board, it's not necessary. First, one end of the crack originates (or terminates), at the edge of the board. The other end stopped at a hole in the board. Just roughen up the surface a little, then apply a generous coat of epoxy... BAM! done...
@@danielmantione On simple single-layer boards, this is an option. I've used a brace and bit to do this , which seems to give a good measure of control and avoids stressing the substrate during drilling. Love the paper-clip trick.
Mike I love The Geek Pub! Always interested in your and David’s projects. I thought maybe this would be from your Petscii Robots arcade machine conversion?
19:47 - I love that high voltage probe.... It's like a blend of the early vacuum tube era, cheesy sci-fi and a magic wand! Also nice to have a safe way of poking round high voltage stuff without it letting the magic smoke out of your own body!
I just love these videos and the way you diagnose problems. I also love the collaboration with David Murray. The retro computer community certainly pulls together when needed!
Just FYI, Adrian, you need to be careful injecting DC into a bridge rectifier. Typically, the bridge rectifier when fed AC, each pair of diodes only conducts for half of the waveform, meaning each pair of diodes has a duty cycle of 50%. But if you feed DC in, then only one pair of diodes is passing all of the current all of the time. And if the company went cheap on the diodes, you can cook the diodes in the bridge rectifier.
@@adriansdigitalbasement2 Adrian... you can look for the datasheet of the voltage regulator to know for sure at what DC voltage the board runs..... instead of trying different voltages.......... then you can set the DC to 2 or 3 volt over that....... or feed the proper voltage directly to the output leg of the regulator to feed the board.....
This could almost have been called "repairing a couple CRT boards with an audio spectrum analyzer". Also ironic how the "good" board was in some way in worse shape than the "bad" one. Excellent job, loved this.
Thank you for sharing that Spectroid App. I am also in my 40s but I can still hear frequencies up to at least 18khz, usually higher. I started hearing a high pitch frequency, turns out my tv is generating a 17khz sound at -60db. I never would have been able to narrow it down.
My dad worked for DEC in Reading, UK in the '70s... they had a floor of something like 250 desks, each with a VT100 on it. I used to be taken there some evenings, and could walk in and pinpoint any monitor that had been left on by sound alone! I'm 56 now, but don't know if I can still hear 15kHz any more, because I haven't seen a CRT in ages!
You are hitting on why I really don't watch David's channel anymore. He is into some neat stuff, but he's that guy. I'm amazed by the sensitivity of the mobile phone microphone! Excellent use of a phone spectrum analyzer.
I'm nearing my 40s, and I can hear the "CRT Hum" only if I turn on my CRT in the dead of the night, with anything else shut down, and I must concentrate as I hear it really faintly. It used to be louder once, as you told :)
Old TVs did that ..... Probable came from the Tube era when the electronics were actually mounted on a chasis and no PCB, just point to point soldering.
The PCBs that run a tv/monitor are generally called a chassis. It's a carried over term from the old vacuum tube TVs that were older than PCBs and just had everything soldered together.
Great video. I love watching the detective like troubleshooting, process of elimination, and other logic approaches to the repair. This is why I'm also a huge fan of TRXLab too.. Both you and his channel quench my appetite for troubleshooting electronics. Thank you!!!
36:37 - when David was on vacation he had a friend over doing a repair for a broken monitor for him. The problem was that the board was cracked similarly to this case. He scraped off a huge part of the solder mask on the ground plane and soldered a piece of paper clip that reinforced the part and also provided conductivity between the two parts. I had success using the same technique on a broken Nintendo 64 controller PCB, you should try it too :)
Great job! Anything CRT-related is an immediate click for me. The L601 inductor is identical to the one on the Wells Gardner K4600 deflection board so I'm not surprised that fixed it. It provides the same function of fine tuning the H.Hold when adjusting the regular pot does not get it to lock on. Happy to see you got it working. Also, those fiberglass pens are anything but. The actual fiberglass pens are known as "Prep Pens." Search A(m)azon for "PrepPen Adjustable Sanding Pen" and those will be much better since they are actual fiberglass pens.
Strange. I use the ones like he has and they work really well. They sure seem like fibreglass. If you touch them, you get tiny little shards embedded in your finger
The cheap phenolic that they use for the PCB, on cheap consumer gear, was always a problem for cracking, even when new. Hard to see the cracks too sometimes. Its like using peanut brittle as a copper substrate. O_o - You can use old used pieces of solder braid wick to jump across cracks. Its already got the solder on it :) and its flexes around stuff nicely when the solder is fluid. Cheers,
Snorted into my coffee at the rapid editing of the chip desoldering montage! Lee Smith did something similar in his last video and I think it's my new favourite thing in retro reapir vids 😋
CRT are dangerous and another smaller UA-camr who you have mentioned has said not to worry about it. I like that you give a warning. Loads of people say they can fix boards but just change all electrolytic capacitors and check for short then give up. Then blame a hard to find ic rather than fix.
I have seen that black oxidation on transistor leads and switch contacts in many 70s amplifiers, I think it may be some sort of tin oxide coming through. It is not necessarily corrosion in the same way as rust or acid damage, but it definitely could cause problems.
To me it seems to be more along the lines of a soot produced from the high voltage, temperature and common dust. I've seen it inside old CRTs and Televisions that I've "played" with, and it just gets everywhere. Once it mixes with any kind of paste like thermal compound and hardens, its just a pain to clean up.
@@jk180 That could be true, I have seen the "soot" before around the HT lead and flyback, but that usually wipes off like dust, the stuff I am talking about does not wipe off and does not require high voltage to form.
It looks like silver or tin oxide. Nasty stuff as it "migrates" over the medium. Similar topics to this would be: - silver migration effect (the deadly killer of early tube era IF cans) - tin whiskers (early germanium and Japanese can transistors) Cheers,
@@EngineeringVignettes Silver migration, or "silver mica disease" in IF cans as some people call it is really annoying indeed, reparable if lucky, but not often. There are all sorts of nasty metallurgical things that can happen to vintage and antique electronics apparently.
36:52 If this is a single layer PCB I highly recommend drilling a hole at the end of that crack to stop if from spreading. Any damage done by drilling can easily be fixed with jumpers wires.
They are referred to as "Monitor Chassis". The Adjustable Coil is the Horizontal Width Coil which adjusts how wide the picture is. As a rule of thumb, you should get about 1K Volts per inch of a Tube at the second anode (Suction Cup attached to the tube). i.e. a 15" Tube should be around 15K volts and a 19" monitor should be around 19K volts, etc... It's also recommended that you don't insert the high voltage probe under the cup while the monitor is powered up. You could easily pop it off the tube and now you have a wire flopping around with thousands of volts coming out of it. When you put the cup back on the tube give it a yank too. If it comes off, you didn't attach it correctly.
I had the EXACT same thing happen to me, but unfortunately it was an Op Amp package for a stereo receiver that went out. The packages looked identical and I didn't think twice about just putting the new one in with the printed side facing the same way and smoked it. Luckily I was able to figure out what had happened, got another part, and it worked. It's not perfect, there's now some noise floor that wasn't there before, so something else got damaged or the part itself is crud, but it works.
If AC is required, how then does Adrian make this work by feeding it only DC? Apparently, AC is not a requirement if you bypass the rectifier circuit, so why even feed the monitor AC in the first place? I'm still a bit puzzled why it didn't work when he was feeding DC through the diodes....?
@@Quickened1 : Feeding DC through the diodes was not a problem, an inductor being out of tune was. As for AC vs DC, throwing DC into an AC supply will either not work (some supplies have capacitors on their input that block DC, or transformer that won't pass DC, and maybe internal circuitry that does the same), only partially work (because some switching supplies have a second internal supply for their control circuitry), or stress components unevenly (such as two diodes in a bridge rectifier passing all of the current, and the other two passing effectively none).
@@absalomdraconis he did have a problem getting anything out of the set when running through the diodes. I also know that the out of tune inductor was part of the problem with the set from the beginning, but had nothing to do with the way he eventually had to supply power beyond the rectifier to get it working at all. He also explained the excess load on the diodes when going through the power supply, but did not explain why that wouldn't generate sufficient frequency within the flyback...
A few bits of PCB material and epoxy on the top side (and into any cracks) would help with preventing those cracks from developing. FWIW I find scratching solder resist with a knife then using a glass fibre pencil to do the final clean up works best.
I'll let David do more cleanup if he wants. :-) The solder mask was unusually thick on this board. A polishing wheel on the Dremel would have probably worked well.
Great tip Aapje. Also for boards that have corners snapped off superglue sticks vero board REALLY well. If you dont have the broken off piece you can shape another piece of board. You've got to be quick though because it sets very quickly on PCBs. Be careful when soldering across the join coz you can get a puff of nasty, acrid smoke in your face.
Cracked PCBs around the flyback are the bane of CRT repairs, been looking at a few monitors on ebay that apparently show no signs of HT, and I'm wondering if they have the same issues, not a hard fix, but very much a pain to trace, stabilise and jump all the cracks with wire or even just solder wick, but it's oh so fulfilling to hear that CRT squee as it fires up properly though... :D
I hated working on the CRT driver boards. The boards I worked on were very tightly jammed with components making them difficult to get probes into various places without getting zapped. The usual fix was as you said the driver chip from what I recall. I wonder if the blackening etches is due to the cracks. With the poor connections, the connections were arcing and further carbonizing the surface of the circuit board.
Really fantastic debugging video. When you first turned on the bad board, having it sideways, and talking with your hands, it was a bit unnerving since you just articulated the possibility of high voltages arcing across the board if not properly grounded. I'm glad you know what you are doing so you can even touch things like the yolk while the monitor is running. Hopefully others don't try and repeat what you do. I used to take old Mac's apart and new how to zap the high voltage from the CRT, but still never felt at ease working with them. Regarding the second PCB with cracked board...finding the end of the crack and drilling a small hole right at the end of it will make sure that the crack doesn't spread.
These kinds of videos are my favorite, any kind of electronics repair is so interesting to watch... would love to see a TTL logic computer repair, like a PDP or an early terminal or something.
In the past two years your skills have reached a wizard like, inspiring level of improvement. I dislike the 8-bit guy exactly because he lacks the motivation or tenacity to really learn how things work, that said, he has other talents of promoting himself and each person is best at something else. Please keep it up, you are a true repairman and I am so happy to see how hard work translates into skills
I'd love to see collaboration between Adrian, 8-bit Guy and Ron @ Joe's Classic Video Games. And because Adrian said "dodgy" so many times in this video....Sorin from Electronic Repair School. (and while we're at it we might as well get Fran Blanche, Ben Eater, Jan Beta, Mr Carlson, Necroware, Noel's Retro Lab, EEVblog, Banjoguy Ollie, Ben Heck......................)
When I was about 9 or 10 my father was fixing a TV on my uncle's house and he keep asking me to say if I was hearing the 15750 humming or not. No adult could hear it. Now I imagine the problem could be on the horizontal oscillator. Nice way to test and adjust the frequency of it.
Knowing that many arcade cabinets do not run at standard NTSC frequencies and seeing that the frequencies were not lining up, I was just waiting for that to turn out to be part of the problem here. Looks like you got lucky on this one! It's something to keep in mind if you work on any arcade cabinet parts in the future.
When the 8 bit guy asks you to do something, you just DO it! Thanks for the spectroid app, that will be useful as I've not heard the horizonal whine for decades now. Nice work, as usual.
Sometimes the board is designed for the tube. I always remember some "flatter" CRT monitors for the Amiga where to be compatible with the Amiga and its 15Khz mode they reused a PCB for a more rounded monitor and the picture didn't look right as a result. But they still shipped it.
If you don't have the CRT 'dag' hooked up you may not even get HV. The CRT outside dag coating along with a similar dag coating on the inside that is connected to the HV terminal, forms the HV filter capacitor. If this isn't present, there is nothing for the flyback/rectifier circuit to charge up, so little HV will be generated. Note that flyback circuits using a voltage tripler will have hv disc capacitors on board, so these WILL produce HV without the CRT ground connected, though maybe not as much as they would with it hooked up.
Excellent video and great repairs! 👍 Yeah, mistakes happened, especially, if part is from another manufacturer.. David should listen to his brother.. 😂
It's so cool that fellow UA-camrs can reach out to each other for help. UA-cam is a very powerful community. Like I have always said, we need to have a UA-cam electronics convention located in a central area in some convention center or stadium, where all the UA-camrs like Shango066, 12 Volt Vids, radiotvphononut, The 8 bit guy and many others come together and display all their repairs and just have a nice gathering. People could come from all over the world and meet their favorite UA-cam stars. Proceeds from admission could go to UA-camrs or be donated to charity.
my 3 thoughts 1) cracked PCBs: use epoxy to stabilize, clean the surface before with acetone and/or glass fiber before 2) i hardly recommend getting an isolation transformer plus a power limiter (like 100W incandescent bulb, with a switch to have unrestricted power). in case look at tube radio channels, they have that tooling for working on their hot chassis. that fiddling with feeding DC somewhere into the board via a FBR gave me "yelling at the screen" moments. 3) speaking of "yelling at screen". The IC being mounted backwards was my first thought when you showed the solder side of the PCB, since the pin1/10 did not correspond to the beveled edge of the IC.
I watch all of your videos as they come out and I just have to say, this was excellent. Of course they always are, but the tips were rapid fire and 40 minutes felt like 20.
That Northridge Fix guy is always fixing boards via bodge wires and copper strips and has a specialty tool that's like a pencil size dremmel just for removing solder mask. Can you look into if you need one of those?
I'm using some "regular" deoxid spray, can you tell us a lilttle more about that QD, why is it good for carbon based posts, how is it different to other deoxid stuff, how does it work?
I use that phone FFT thing as well, really nice when you have a phone that does high sampling rate. I think mine does 96 kHz, which results in a maximum frequency of 48 kHz, and I've use it to see a sharp 32768 Hz signal, hahah. Really useful!
Nice job Adrian. Dave has lots of knowledge but sometimes he is so busy with lots of things in head and the game that is normal to miss something. Funny not even the technician notice, but his brother seen straight away haha. Kudos for Dave to ask for help and for you for helping :)
Water thin CA would migrate into the cracks via capillary action. Also, a flat plate of something not conductive could be CAed across the cracks for more reinforcement.
If the surface of the metal tab is exposed to Moisture in the air the.. Tarnish, Oxidation begins but its most likely caused by the sulphur from the capacitors. Great Fix Adrian! Oh the can you called an inductor is a IF transformer Not an inductor.. the change on your phone app was caused by you adjusting the Oscillator coil - Tuning Capacitor. 🖖👍
37:30 next time drill a hole at the end of the crack... That'll stop the crack from running and take the stress off of it...A tiny hole will suffice...We do that in our aircraft shop on a regular basis...
You can glue perfboard or bare PCB material with epoxy to reinforce it. Super easy. You can drill holes or cut out around any components or pins in the way to get it flush. Same for mounting holes. Overlaying layers of PCB is strong and permanent
![Adrian's Digital Basement ][](http://yt3.ggpht.com/ytc/AIdro_k7CrQRe71qN6c0Ua7A1P_I8KkxjqLa70u0zYeCvdvnKw=s48-c-k-c0x00ffffff-no-rj)
If you find the end of a crack in the board, drill a hole through it (where it ends). That stops the crack from continuing.
There is enough space to drill multiple holes without breaking traces. I'd drill some holes on both ends of the crack and then use cable ties to tie them together. That should give it enough mechanical strength to last the ages, in combinaties with the wires that prevent electronical failures. A technique that I have used in the past on a CRT with a crack was to remove solder mask from broken traces and solder a paper clip over the strace, completely covering it with solder tin. The paper clip provides mechanical strength, while the solder tin takes care of conductivity.
@@danielmantione True, "drift-stitches" would work :)
Well, in the case of this board, it's not necessary. First, one end of the crack originates (or terminates), at the edge of the board. The other end stopped at a hole in the board. Just roughen up the surface a little, then apply a generous coat of epoxy... BAM! done...
i would use some glue to keep the board ends together, and then drill a small hole in the end of the crack to stop it
@@danielmantione On simple single-layer boards, this is an option. I've used a brace and bit to do this , which seems to give a good measure of control and avoids stressing the substrate during drilling. Love the paper-clip trick.
I love "crossover" videos like this.
Two for the price of one! Awesome that you suggested sending both boards, it was meant to be!
AWESOME! I love your thoroughness. The game is MoonBase. A Japanese knock off of Space Invaders.
Mike I love The Geek Pub! Always interested in your and David’s projects. I thought maybe this would be from your Petscii Robots arcade machine conversion?
@@RetroFett No. Different video that's not out yet. Thanks for your support!
Hey Mike, If David needs help with his PETSCII Robots arcade, Adrian's Digital Basement can save the day!
Space Invaders was Japanese to begin with. It was originally developed by Taito.
19:47 - I love that high voltage probe.... It's like a blend of the early vacuum tube era, cheesy sci-fi and a magic wand! Also nice to have a safe way of poking round high voltage stuff without it letting the magic smoke out of your own body!
I just love these videos and the way you diagnose problems. I also love the collaboration with David Murray. The retro computer community certainly pulls together when needed!
Always love the CRT videos and the way you explain the diagnostic of a circuit. 🙂👍👍
Just FYI, Adrian, you need to be careful injecting DC into a bridge rectifier. Typically, the bridge rectifier when fed AC, each pair of diodes only conducts for half of the waveform, meaning each pair of diodes has a duty cycle of 50%. But if you feed DC in, then only one pair of diodes is passing all of the current all of the time. And if the company went cheap on the diodes, you can cook the diodes in the bridge rectifier.
Dagnabbit. You addressed this in the video. At least you recognized that there might be an issue! ^-^
The editing on that desoldering section at the beginning was epic. 10/10 😁
I use that same app on my phone all the time. It's really useful for monitors and cassette deck calibration, too.
With one of those tapes with a constant frequency?
@@adriansdigitalbasement2 Adrian... you can look for the datasheet of the voltage regulator to know for sure at what DC voltage the board runs..... instead of trying different voltages.......... then you can set the DC to 2 or 3 volt over that....... or feed the proper voltage directly to the output leg of the regulator to feed the board.....
@@Ramdileo_sys Or just call David and ask him to send you a picture of the transformer... or probe it.
adrian does what 8 bits don't
Wonderful analysis of the problems. Thats the reason why I love your channels. Thanks for the video!
37:00 if you drill a small hole in the PCB at the end of the crack,
that will prevent the crack from developing further.
Yes. Like on crash cymbals when cracks :)
Well, David is excellent with a dremel and a screwdriver.
Just like they do on aircraft!
This could almost have been called "repairing a couple CRT boards with an audio spectrum analyzer". Also ironic how the "good" board was in some way in worse shape than the "bad" one. Excellent job, loved this.
Thank you for sharing that Spectroid App. I am also in my 40s but I can still hear frequencies up to at least 18khz, usually higher. I started hearing a high pitch frequency, turns out my tv is generating a 17khz sound at -60db. I never would have been able to narrow it down.
My dad worked for DEC in Reading, UK in the '70s... they had a floor of something like 250 desks, each with a VT100 on it. I used to be taken there some evenings, and could walk in and pinpoint any monitor that had been left on by sound alone! I'm 56 now, but don't know if I can still hear 15kHz any more, because I haven't seen a CRT in ages!
You are hitting on why I really don't watch David's channel anymore.
He is into some neat stuff, but he's that guy.
I'm amazed by the sensitivity of the mobile phone microphone! Excellent use of a phone spectrum analyzer.
I'm nearing my 40s, and I can hear the "CRT Hum" only if I turn on my CRT in the dead of the night, with anything else shut down, and I must concentrate as I hear it really faintly.
It used to be louder once, as you told :)
In the arcade world, people refer to the board as the chassis (so when they say "chassis" they mean the board, not the metal framework).
Thats not confusing at all LOL
@@kelvin1316 one of the many things you have to just accept when you start collecting arcade machines. 🤔
@@JamesPotts Well, after all, the board is the frame upon which the entire digital architecture is built upon...
For me and I’m arcade world, the whole assembly is the chassis, and once the PCB is removed I call it the PCB and the rest remains the chassis.
Old TVs did that ..... Probable came from the Tube era when the electronics were actually mounted on a chasis and no PCB, just point to point soldering.
The PCBs that run a tv/monitor are generally called a chassis. It's a carried over term from the old vacuum tube TVs that were older than PCBs and just had everything soldered together.
Great video. I love watching the detective like troubleshooting, process of elimination, and other logic approaches to the repair. This is why I'm also a huge fan of TRXLab too.. Both you and his channel quench my appetite for troubleshooting electronics. Thank you!!!
36:37 - when David was on vacation he had a friend over doing a repair for a broken monitor for him. The problem was that the board was cracked similarly to this case. He scraped off a huge part of the solder mask on the ground plane and soldered a piece of paper clip that reinforced the part and also provided conductivity between the two parts. I had success using the same technique on a broken Nintendo 64 controller PCB, you should try it too :)
Great job! Anything CRT-related is an immediate click for me. The L601 inductor is identical to the one on the Wells Gardner K4600 deflection board so I'm not surprised that fixed it. It provides the same function of fine tuning the H.Hold when adjusting the regular pot does not get it to lock on. Happy to see you got it working. Also, those fiberglass pens are anything but. The actual fiberglass pens are known as "Prep Pens." Search A(m)azon for "PrepPen Adjustable Sanding Pen" and those will be much better since they are actual fiberglass pens.
Strange. I use the ones like he has and they work really well. They sure seem like fibreglass. If you touch them, you get tiny little shards embedded in your finger
Needs more paperclips. Great job fixing it!
This was a brilliant repair. Hats off!
CRTs are no challenge for the wizard of CRTs; Mr. Adrian Black! Bravo.
Love the ingenuity of using the phone to measure the audio frequency!
Always listen to youre big brother, LOL
Good to see the 8-bit Guy is letting someone else handle the CRT repairs.
Yes. He has his talents, but i don't think that electronics are at the top of the list. 😉
@@IDPhotoMan Yep , thats the right way round (when its not) is so David
Or any other repair. He should _not_ do repairs. 😂
Yes, if he had done it himself they would have been "dremeled" and "paperclipped" into a billion pieces. 😆
@@bsvenss2 how do you know, if he has not tried that paperclip for this 😝
You missed your calling Adrian. You should have been a 1960s TV repairman. Those guys would make house calls.
Two of my favorite UA-camrs David and Adrian
The cheap phenolic that they use for the PCB, on cheap consumer gear, was always a problem for cracking, even when new. Hard to see the cracks too sometimes. Its like using peanut brittle as a copper substrate. O_o
-
You can use old used pieces of solder braid wick to jump across cracks. Its already got the solder on it :) and its flexes around stuff nicely when the solder is fluid.
Cheers,
I've recently discovered your channel and I'm absolutely hooked!!! Its freaking awesome!!!
Welcome!
Snorted into my coffee at the rapid editing of the chip desoldering montage! Lee Smith did something similar in his last video and I think it's my new favourite thing in retro reapir vids 😋
CRT are dangerous and another smaller UA-camr who you have mentioned has said not to worry about it.
I like that you give a warning.
Loads of people say they can fix boards but just change all electrolytic capacitors and check for short then give up.
Then blame a hard to find ic rather than fix.
David made a good choice sending it to you... I've seen some of his repair efforts
Dremel to the IBM case, and the paperclip power switch, come to mind!
@@tekvax01 Specifically that as an example
Couldn’t shoot it into working?
I have seen that black oxidation on transistor leads and switch contacts in many 70s amplifiers, I think it may be some sort of tin oxide coming through. It is not necessarily corrosion in the same way as rust or acid damage, but it definitely could cause problems.
To me it seems to be more along the lines of a soot produced from the high voltage, temperature and common dust. I've seen it inside old CRTs and Televisions that I've "played" with, and it just gets everywhere. Once it mixes with any kind of paste like thermal compound and hardens, its just a pain to clean up.
@@jk180 That could be true, I have seen the "soot" before around the HT lead and flyback, but that usually wipes off like dust, the stuff I am talking about does not wipe off and does not require high voltage to form.
It looks like silver or tin oxide. Nasty stuff as it "migrates" over the medium. Similar topics to this would be:
- silver migration effect (the deadly killer of early tube era IF cans)
- tin whiskers (early germanium and Japanese can transistors)
Cheers,
@@EngineeringVignettes that’s good to know. Thanks
@@EngineeringVignettes Silver migration, or "silver mica disease" in IF cans as some people call it is really annoying indeed, reparable if lucky, but not often. There are all sorts of nasty metallurgical things that can happen to vintage and antique electronics apparently.
36:52 If this is a single layer PCB I highly recommend drilling a hole at the end of that crack to stop if from spreading. Any damage done by drilling can easily be fixed with jumpers wires.
Thanks for the video. I'm a fan of both your channel and 8bit guy. Really like the collaboration. And I need help with CRT diagnosis, so win win.
They are referred to as "Monitor Chassis". The Adjustable Coil is the Horizontal Width Coil which adjusts how wide the picture is. As a rule of thumb, you should get about 1K Volts per inch of a Tube at the second anode (Suction Cup attached to the tube). i.e. a 15" Tube should be around 15K volts and a 19" monitor should be around 19K volts, etc... It's also recommended that you don't insert the high voltage probe under the cup while the monitor is powered up. You could easily pop it off the tube and now you have a wire flopping around with thousands of volts coming out of it. When you put the cup back on the tube give it a yank too. If it comes off, you didn't attach it correctly.
Great video. It's like a crime scene. It was ... No spoiler!
I had the EXACT same thing happen to me, but unfortunately it was an Op Amp package for a stereo receiver that went out. The packages looked identical and I didn't think twice about just putting the new one in with the printed side facing the same way and smoked it. Luckily I was able to figure out what had happened, got another part, and it worked. It's not perfect, there's now some noise floor that wasn't there before, so something else got damaged or the part itself is crud, but it works.
Wasn't expecting to see a comment from an prior coworker on one of my favorite channels... small world we live in. :D
This is what I do all the time. Fixing arcade monitors. Looking forward to you getting a Coleco Adam.
Arcade cabs use a isolation transformer, so Isolated line ac voltage into the monitors. Arcade monitors are HOT chassis, so this is required.
It’s low voltage AC, no isolation required.
If AC is required, how then does Adrian make this work by feeding it only DC? Apparently, AC is not a requirement if you bypass the rectifier circuit, so why even feed the monitor AC in the first place? I'm still a bit puzzled why it didn't work when he was feeding DC through the diodes....?
CRT TVs from early 80s were hot chassis .... I think that they stopped doing that when they got AV inputs and ouputs ... just imagine the explosion.
@@Quickened1 : Feeding DC through the diodes was not a problem, an inductor being out of tune was.
As for AC vs DC, throwing DC into an AC supply will either not work (some supplies have capacitors on their input that block DC, or transformer that won't pass DC, and maybe internal circuitry that does the same), only partially work (because some switching supplies have a second internal supply for their control circuitry), or stress components unevenly (such as two diodes in a bridge rectifier passing all of the current, and the other two passing effectively none).
@@absalomdraconis he did have a problem getting anything out of the set when running through the diodes. I also know that the out of tune inductor was part of the problem with the set from the beginning, but had nothing to do with the way he eventually had to supply power beyond the rectifier to get it working at all. He also explained the excess load on the diodes when going through the power supply, but did not explain why that wouldn't generate sufficient frequency within the flyback...
A few bits of PCB material and epoxy on the top side (and into any cracks) would help with preventing those cracks from developing.
FWIW I find scratching solder resist with a knife then using a glass fibre pencil to do the final clean up works best.
I'll let David do more cleanup if he wants. :-) The solder mask was unusually thick on this board. A polishing wheel on the Dremel would have probably worked well.
@@adriansdigitalbasement2 Green rubber one works fine. Even from Aliexpress. Different colors have different density but green is ok.
I recently had to fix a deflection board for the vector monitor in my Star Wars cabinet. That was an adventure!
Great tip Aapje. Also for boards that have corners snapped off superglue sticks vero board REALLY well. If you dont have the broken off piece you can shape another piece of board. You've got to be quick though because it sets very quickly on PCBs. Be careful when soldering across the join coz you can get a puff of nasty, acrid smoke in your face.
Cracked PCBs around the flyback are the bane of CRT repairs, been looking at a few monitors on ebay that apparently show no signs of HT, and I'm wondering if they have the same issues, not a hard fix, but very much a pain to trace, stabilise and jump all the cracks with wire or even just solder wick, but it's oh so fulfilling to hear that CRT squee as it fires up properly though... :D
I hated working on the CRT driver boards. The boards I worked on were very tightly jammed with components making them difficult to get probes into various places without getting zapped. The usual fix was as you said the driver chip from what I recall.
I wonder if the blackening etches is due to the cracks. With the poor connections, the connections were arcing and further carbonizing the surface of the circuit board.
Really fantastic debugging video. When you first turned on the bad board, having it sideways, and talking with your hands, it was a bit unnerving since you just articulated the possibility of high voltages arcing across the board if not properly grounded. I'm glad you know what you are doing so you can even touch things like the yolk while the monitor is running. Hopefully others don't try and repeat what you do. I used to take old Mac's apart and new how to zap the high voltage from the CRT, but still never felt at ease working with them.
Regarding the second PCB with cracked board...finding the end of the crack and drilling a small hole right at the end of it will make sure that the crack doesn't spread.
Another great video. Gotta love a chassis repair video.
36:28 - Maybe you could borrow David's? 😁
These kinds of videos are my favorite, any kind of electronics repair is so interesting to watch... would love to see a TTL logic computer repair, like a PDP or an early terminal or something.
Percussive diagnosis.
9-bit Guy got a 2-fer!
I’m at the stage in my life when I can hear a CRT whistle everywhere I go, my Dr calls it tinnitus
14:27 I like how Adrian warn that high voltage arc can harm your hardware and said like nothing about yourself. :D
In the past two years your skills have reached a wizard like, inspiring level of improvement. I dislike the 8-bit guy exactly because he lacks the motivation or tenacity to really learn how things work, that said, he has other talents of promoting himself and each person is best at something else. Please keep it up, you are a true repairman and I am so happy to see how hard work translates into skills
Excellent work! Long video but worth its weight in gold. Learned a ton. Thanks for sharing!!
Only 40 minutes! I could easily watch these for over an hour!
Set the controls for the heart of the sun.
I'd love to see collaboration between Adrian, 8-bit Guy and Ron @ Joe's Classic Video Games. And because Adrian said "dodgy" so many times in this video....Sorin from Electronic Repair School. (and while we're at it we might as well get Fran Blanche, Ben Eater, Jan Beta, Mr Carlson, Necroware, Noel's Retro Lab, EEVblog, Banjoguy Ollie, Ben Heck......................)
Nobody says "dodgy" like DiodeGoneWild though
When I was about 9 or 10 my father was fixing a TV on my uncle's house and he keep asking me to say if I was hearing the 15750 humming or not. No adult could hear it. Now I imagine the problem could be on the horizontal oscillator. Nice way to test and adjust the frequency of it.
Knowing that many arcade cabinets do not run at standard NTSC frequencies and seeing that the frequencies were not lining up, I was just waiting for that to turn out to be part of the problem here. Looks like you got lucky on this one! It's something to keep in mind if you work on any arcade cabinet parts in the future.
When the 8 bit guy asks you to do something, you just DO it!
Thanks for the spectroid app, that will be useful as I've not heard the horizonal whine for decades now. Nice work, as usual.
Sometimes the board is designed for the tube. I always remember some "flatter" CRT monitors for the Amiga where to be compatible with the Amiga and its 15Khz mode they reused a PCB for a more rounded monitor and the picture didn't look right as a result. But they still shipped it.
Nice job. You could drill a small hole at the end of the crack in the board to stop it continuing across the pcb.. And fill it with epoxy after.
your a really clever guy Adrian really enjoy watching your video's
Hyper clever guy and super knowledgeable. One of my favourite personalities on YT
Repairing tracks, solder wick is your friend.. handle ludicrous amounts of current. Also very strong..
Great job. I really enjoyed this one. 👍
If you don't have the CRT 'dag' hooked up you may not even get HV. The CRT outside dag coating along with a similar dag coating on the inside that is connected to the HV terminal, forms the HV filter capacitor. If this isn't present, there is nothing for the flyback/rectifier circuit to charge up, so little HV will be generated. Note that flyback circuits using a voltage tripler will have hv disc capacitors on board, so these WILL produce HV without the CRT ground connected, though maybe not as much as they would with it hooked up.
That makes sense. I've never tried to operate a CRT without the ground connected.
@@adriansdigitalbasement2 Wasn’t there a missing ground on the Watchman you repaired? I remember you were getting a tingle from that one.
Adrian is a wizard! Great job!
Some SIP parts have variants which have a reverse pinout.
I love crossovers between awesome channels! Thanks! 😊
You Sir, are a delight. Thanks in earnest. a fan :)
Excellent video and great repairs! 👍
Yeah, mistakes happened, especially, if part is from another manufacturer.. David should listen to his brother.. 😂
Wow. Nice fix. One of your better videos.
Nice work Adrian.
if I could give two thumbs up to this one I would. Spot on fault finding. Top video.
It's so cool that fellow UA-camrs can reach out to each other for help. UA-cam is a very powerful community. Like I have always said, we need to have a UA-cam electronics convention located in a central area in some convention center or stadium, where all the UA-camrs like Shango066, 12 Volt Vids, radiotvphononut, The 8 bit guy and many others come together and display all their repairs and just have a nice gathering. People could come from all over the world and meet their favorite UA-cam stars. Proceeds from admission could go to UA-camrs or be donated to charity.
Adrian and I will both be at VCF next month, along with LGR, Computer Clan, and a few others.
my 3 thoughts
1) cracked PCBs: use epoxy to stabilize, clean the surface before with acetone and/or glass fiber before
2) i hardly recommend getting an isolation transformer plus a power limiter (like 100W incandescent bulb, with a switch to have unrestricted power). in case look at tube radio channels, they have that tooling for working on their hot chassis. that fiddling with feeding DC somewhere into the board via a FBR gave me "yelling at the screen" moments.
3) speaking of "yelling at screen". The IC being mounted backwards was my first thought when you showed the solder side of the PCB, since the pin1/10 did not correspond to the beveled edge of the IC.
I watch all of your videos as they come out and I just have to say, this was excellent. Of course they always are, but the tips were rapid fire and 40 minutes felt like 20.
Excellent repair video!!!!
awesome to see you fix it adrian
i was laughing at him for messing it up in first place and his bro was right lol
That Northridge Fix guy is always fixing boards via bodge wires and copper strips and has a specialty tool that's like a pencil size dremmel just for removing solder mask. Can you look into if you need one of those?
Assuming a 24Vrms ac signal when rectified would be about 17V DC before diode voltage drop.
Yeah, fix them boards! Alright!
Adrian is a very very good tech.
Analog boards seem to be an appropriate name for those.
I'm using some "regular" deoxid spray, can you tell us a lilttle more about that QD, why is it good for carbon based posts, how is it different to other deoxid stuff, how does it work?
I use that phone FFT thing as well, really nice when you have a phone that does high sampling rate. I think mine does 96 kHz, which results in a maximum frequency of 48 kHz, and I've use it to see a sharp 32768 Hz signal, hahah. Really useful!
Nice job Adrian. Dave has lots of knowledge but sometimes he is so busy with lots of things in head and the game that is normal to miss something. Funny not even the technician notice, but his brother seen straight away haha. Kudos for Dave to ask for help and for you for helping :)
The technician told Dave it was bad. Then Dave ordered the replacement and misinstalled it.
Water thin CA would migrate into the cracks via capillary action. Also, a flat plate of something not conductive could be CAed across the cracks for more reinforcement.
I totally read that as Dave Murray from Iron Maiden lol
If the surface of the metal tab is exposed to Moisture in the air the.. Tarnish, Oxidation begins but its most likely caused by the sulphur from the capacitors. Great Fix Adrian!
Oh the can you called an inductor is a IF transformer Not an inductor.. the change on your phone app was caused by you adjusting the Oscillator coil - Tuning Capacitor. 🖖👍
37:30 next time drill a hole at the end of the crack... That'll stop the crack from running and take the stress off of it...A tiny hole will suffice...We do that in our aircraft shop on a regular basis...
how does deoxit damage the carbon pots?
Bro..... You gotta fix them with a paperclip and send them back. :3
Look at the PN on the regulator and then set the voltage a few volts above it's datasheet spec.
Cracked SRBP boards superglue on the crack after the jumpers will help hold the board from cracking further.
You can glue perfboard or bare PCB material with epoxy to reinforce it. Super easy. You can drill holes or cut out around any components or pins in the way to get it flush. Same for mounting holes. Overlaying layers of PCB is strong and permanent
Adrian is the GOAT