Rebuilding A Commodore 64 Power Supply
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- Опубліковано 22 тра 2024
- In this episode I detail how I go about rebuilding C64 power supplies. I also give some alternatives to rebuilding. And of course Penny makes an appearance.
Chapters:
00:00 - Intro
01:17 - Alternatives To Rebuilding
06:40 - The Plan And Tools Needed
15:00 - Removing The Potting
22:35 - Wiring
28:06 - Initial Test
34:38 - Epoxy and Fuse
39:44 - Tracing C64 Wires
44:11 - Final Test With A C64
46:03 - Wrap Up
5V 3A Mean Well Power Supply
www.jameco.com/webapp/wcs/sto...
9VAC Wall Transformer
www.jameco.com/webapp/wcs/sto...
Jan Beta Video • Building a DIY C64 Pow...
@JanBeta
Kevin Ottum Video • Commodore 64 "Re-Brick...
Music used by permission:
“Fakebit World” and "Cheese Brickwall" by Malmen
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“Noisette Part A” by CL Collaboration
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At around 18:00 regarding potting of the power supply I would argue it is somewhat related to your second point: mechanical stability and return rate/failure rate. Remember that a lot of these machines were sold in large department stores across the US and if the return rate of a product was high for whatever reason Commodore would’ve ended up selling a lot less or losing money since those large stores quickly return the money to their customers and the bad product to the manufacturer. And maybe even not buying from them again. Thanks for the video!
Thanks for giving credit! I haven't had a chance to watch your whole video yet, but always interested in what methods others have developed from my original Re-Brick design. I've made some changes myself, but haven't done an updated video in 7 years!
I can't believe how easy your potted brick guts came out completely so easily. I ended up having to use a skinny screwdriver and heat to get it out. I did reuse the original transformer but replaced the 5V section with a Meanwell supply.
A trick when testing rebuilt PSUs (I have built two so far) that I picked up from one of the UA-cam channels, is to get some tubing cut to length and drop it around the pins. (I use either spare heat shrink or the outer sheath from a cable you have stripped off). That way when you poke your multimeter probes in, there's no chance to short between pins :-)
That's a good tip
Either put it around the tips inside the connector or on the tips of the probes. Either way is better than nothing. heh
Great project and a really useful one.
One thing to mention is when hooking up the AC line cord that it should be rung out and the wide blade of the plug should be used as neutral, if the plug doesn’t have a wide blade look at a receptacle and see which slot is widest and use the blade on the plug that correlates to that. I’d also use heat shrink or electrical tape to cover the contact tabs on the fuse holder.
Nice video however! Thx!
Yeah, I like when people use soldering and shrink-tubing instead of electrical tape, because that heat-shrink tubing is SO pro-quality in comparison to a tape that can unravel as it loses adhesion! I bet heat-shrink tubing buys you just about an immeasurable amount more longevity than tape! I bet that tubing would easily outlast the components. I love using it for most of my wire splices.
Wow, congrats on building a new PSU in that old case without having to do it from scratch! I love the idea of just using a shelled "wall wart" for one (or even both) of the sides.
Some 4" cable ties or small gauge spiral wrap might work for improving your wire dressing inside the case. In the old days we'd have used lacing cord. but that stuff is a hassle to get right even when you have plenty of room.
As an alternative to a fuse, try a miniature circuit breaker. These can be reset once a problem is corrected instead of needing to be replaced like a cartridge fuse would. (All things for a price, though - it depends on whether you are designing for durability or lower cost.)
Potting was generally used to enhance structural solidity and insulation, and may have been a design feature used to achieve a UL rating for the unit.
I personally would have epoxied stand offs onto the bottom cover for the switching power supply, and transformer.
I have done it that way too, but I just don't ever plan on changing it so it not worth the hassle for me.
This is an excellent setup. I think the only addition that I would make is a switch for people that don’t want to leave the power supply on all the time but don’t want to have to unplug it. Excellent tutorial! 👍 Just quick add-on comment; to secure the wires to the walls of the power supply you can use a zip tie bracket called a TC105 and glue that to the walls and then zip tie the wires in place.
Thanks
We’ve had those cream colored cases on this side of the pond too. It’s just that they already have a fuse holder that’s drilled through the case. That makes the resin block much more troublesome to remove as you have to first chip the fuse holder loose from the resin so that it’s not in the way. Well, I suppose you could use side cutters to break the holder. Good and informative video!
Interesting. I wasn't aware that the EU versions had a fuse originally.
Amazed at how easy it was for you to dislodge the epoxy. I had the most difficult time with mine. My Re-Brick source was an older black one. I almost gave up trying to get through this step because I was close to damaging the case. It survived though and my Re-Brick is still going strong after several months.
Awesome. I have done this four or five times. One came out immediately. One I found some plastic studs on the side that were making it really difficult and I had to clip away.
That is in fact what I had in my black brick. Turns out those side pieces aided me in securing the internals so I went from hating them to liking them pretty fast.
If you have a vise, you can take the small black power supply and put it in the vise corner to corner , diagonal, and squeeze with the vise, it will pop the lid off.
I'll try that
I need to.try this at some point. Great video. Just subscribed. 😁👍
Thanks
Cool video, thanks!
I have many Commodore 64 power supplies. I found one was a unpotted one so I opened it up and fitted a step down aliexpress regulator on the dc voltage output. Did the job and provides a nice low voltage. As far as I know there's no issues with the Ac power output from these so I left that side alone.
Yeah. The AC transformer should be fine.
Meanwell also makes a replacement supply that fits the 1541.
Nice job, especially keeping it a linear power supply.
For the bottom popping, maybe epoxying a couple of inner lips on the long sides could help, as you'd need to pull the cover until the lips are completely free.
For opening these kind of power supplies I use a large spatula/pizza cutter. Sometimes a couple of hits with a rubber mallet can help when the case is glued shut.
Any advantages to linear power supply?
@@blackterminal the voltage they output has less noise. Do in this case the 9V rail will be less noisy than the 5V rail.
My understanding is that some electronics can be affected by such noise and misbehave.
Great video with a good, detailed explanation. I am designing my own power supply these days for my C64C. The power section of the Longboard and Shortboard are quite different. On the long board, there is on board power regulators (7805 and 7812) which are used to power the VIC-II and the SID only. The rest of the 5V logics are powered from the 5V coming from the brick. I think Commodore preferred this method to keep the very noise sensitive SID and the VIC-II isolated prom the noise generated by the rest of the board. On the shortboards, there is no onboard voltage regulators, everything is powered from the 5V coming from the brick, except for the 9V pin of the new version HMOS 8580 SID. It requires a much lower current, so they just put together a simple zener-transistor regulator for it. Using a modern switch mode 5V regulator in the brick will work flawlessly for the Longboard, I am almost sure. What worries me is the shortboard. Switch mode regulators will have noise (in the form of an AC ripple on top of the DC), powering the SID and the VIC-II with these may cause some audible noise on the audio out, and, although less likely, may cause some video interference too. I know that all the 3rd party replacement PSUs have switch mode regulators, and I haven't seen complaints on this, but I am thinking maybe most people use their C64s with audio from monitor/TV speakers, and a slight noise won't be very noticeable in such a set up. But if one had a decent speaker system connected (like I do), maybe it will become an issue?
Perhaps. I am due for some C64 repairs. Maybe I will have a closer listen and see if and additional noise is detectable.
@@RetroHackShack Thanks for the reply. That will be a very interesting information. I am designing my PSU to have an old school LM338 metal can adjustable regulator. The cables that Commodore used are marginally thin for the job. I will have 4x 0.75mm² cable in between the PSU and the C64. Custom wound transformer will have one secondary winding for 9VAC @10VA, and another 8VAC @20VA for the 5VDC regulator. The smaller (within spec) voltage for the input for the LM338 will create best possible heat dissipation. Waiting for your listening test results, also please do check for small, hard to see video artifacts.
Jan Beta did one in an red and black case, He used all new components as well as a new circuit board design. It was really nice.
I remember that one. I love to see what Jan comes up with.
Really well done. The only additional thing I would like to see would be small led volt and amp meters for the two lines just for extreme geekness.
You could solder in two cheap USB tester displays in parallel with the 5V line, but not sure if it would work with the 9V AC line unless you also include a small rectifier before the USB tester.
Good job.
Nice video! A great topic. Coincidentally, I purchased a Keelog PSU just over a month ago. After some testing and research (research that I should have done prior to purchasing) I cannot recommend the Keelog PSUs, it outputs rather high voltage on the AC side -- 13.4VAC with no load, in my case -- even under load the voltage is quite high AND will cause the un-heatsinked regulators on older C64 motherboards like ASSY 326298 to overheat to the point of failing. Anyway, my two cents.
Subbed! Keep up the great work!
Thanks for sharing that. I have never tried one before so that is welcome feedback.
My Keelog experience was not good either. I will totally admit that I bought one out of curiosity and a bit of espionage. I wanted to see how they got that output cable to be so supple and flexible. All I've ever been able to find for the Nu-Brick that's flexible enough is a white cable (Ray Carlsen uses the same cables) so I was intrigued. It turned out it was BS. The flexible-looking cable in the photo on Keelog's website wasn't a photo at all, but a 3D render. It was as stiff as every other black cable I've ever seen! Then I plugged it into my tester, which puts a 5-ohm resistive load on the 5vdc, and I got 4.75vdc out. Needless to say, it was unreliable on a real C64 as well. And because I bought it on Ebay and let it sit in the box for 3 months, they didn't feel obliged to replace it for me. So much for Keelog.
I remember hearing that potting the supply helped to reduce audible noise. I also heard it was a business decision to make the supply irreparable, thus help increase revenue by selling replacements.
Interesting
I have one of the Nu-Brick's. They are awesome. And yes, metal case. I don't think he is making them any more but if he is, totally worth it.
Thanks! I think last time we talked, I was thinking I wasn't going to be able to get parts for the Nu-Brick anymore, but I've got cases on order. I've been waiting 2 months for them to arrive, so let's hope!
@@ottumland Yeah, I remember that. I still use my Nu-Brick to this day. Have you considered making an Amiga PSU?
@@cbmeeks I do! Send me a message and I'll share details.
"How to OUCH!" XD That's hilarious. Anyway, I have been looking for a video like this. I'll definitely use this info... for getting a C64 first.
I have some of those potted supplies. Haven't thrown out . I'd be less keen on cutting a hole for a led. Understand why you like it though. On the one I altered it had s open grill so a led can be left inside
Im about to build the same power supply with the same parts:) cant wait to try my working ebay treasure :) long life to Commodore 64!! thanks for the tutorial video :)
Good luck!
@@RetroHackShack thanks!!
I have a 9v AC power supply (wall wart) that I was going to use for this purpose. On a hunch I decided to test it. The output was 12.45volts!! So anyone watching this please test your transformers and make sure they are not outputting over 10v
AC transformers will always be high when not connected to a load. To truly test it, measure under load.
@@RetroHackShackI've been watching several videos on this subject with many people explaining how to test the power supply and none of them are under load and showing between 9 & 10 volts AC.
Cool! I’m always pro preserving hardware. No matter the state!
You might want to try to preserve the original transformer. You could by using a metal saw to cut the epoxy between the original transformer and PCB.
For your current build, I think I would’ve mounted the transformer upside down. You’ve done a very nice job though!
Thank you for the nice video!
Thanks for the tips!
I've had the exact same idea! Why throw away a perfectly good transformer, esp. since it's becoming a rarity nowadays.
@@VioletGiraffe love the old heavy power supplies. My daughter was surprised how heavy they are compared to a modern USB supply. Haha. :)
It never would have occurred to me that the potting may not be bonded to the case, almost defeats the propose of potting (which is almost always securing IP incidentally). Also a bit of heat gun may or may not help this process in in a few places.
Hi Aaron. Well done. I need to do this as well. Similar to yours, I was going to gut a 9VAC adapter. However, I have considered using a 5v 2a usb adapter for the 5v rail. I see you went with the larger Meanwell. Is there any advantage of the meanwell over a usb adapter? Thank you for the great video.
Thanks! The Mean Well is adjustable and better built than your typical 5V wall wart. However, there is no reason why it shouldn't work.
There's plenty of room in there to cut out the 5V regulator wires and replace it with a cheap UBEC as used in the RC space. Much easier than removing the innards and replacing a otherwise reliable 9VAC transformer.
www.lemon64.com/forum/viewtopic.php?t=48451
Thks!
Fantastic video. I have one more connection to make that I am confused about. The ground wire coming from C64 4-prong connector cable, is that going to the "GROUND" screw on my Meanwell RS-15-5, or is it going to the "-V" screw on there? If it just connects to the same "GROUND" as the one from the AC MAINS, does anything connect to the "-V" screw? Thank you for your help!
That one goes to the -V on the DC voltage output and not the earth ground.
@@RetroHackShack thank you so much for helping me. I used a case from an old printer PSU so it came out a bit smaller and everything barely fit. Really appreciate the shrink tubing tips as well
That's great!
I wonder if a good addition would be an in-line power switch on the brick? That would not only completely disconnect the C64 from power when left unattended but potentially save wear and tear on the C64 power switch.
Personal preference I think. There is not a lot of room, but there is enough for a switch.
Hi. I have the same multimeter. Could you tell us where you bought those hooked probe extensions, please?
Amazon
Nice job with the rebricking! Nobody should be using those old bricks as-is.
I happen to know my wall outlets are not grounded. You mentioned the meanwell needs an earth ground from the plug. In what way would the lack of ground affect this power supply build?
Not exactly sure, but it is probably used as a reference for balancing the load on the AC. You might be able to find other supplies that don't need an earth connection.
Surely in the USA it's usually 'Live(or Line)' and 'Neutral' like it is in the UK. Also my pet hate are block rectifiers like that round thing on the 5v supply mains input. I would fit 4 off 1N4007 if I were doing this.
Good video. I plan to do the same thing but possible with the addition of a crowbar circuit, since switching power supplies can have somewhat wide tolerances for output voltage.
Scratch that, I was able to remove the original transformer from the epoxy, it chips away fairly easily. I think I'll just build a new linear supply with crowbar/protection circuit.
Cool. Let me know how it comes out.
@@RetroHackShack Will do, gonna try to mock it up tonight assuming I have everything I need.
@@RetroHackShack Made a crowbar circuit using a TL431 reference and a MAC223 Triac (stuff I had on hand). For the voltage divider and to set the trip point, I used a couple of 5k trimmer pots. Adjusted the pots until it would trip consistently at anything 5.3V or above and blow the fuse. Since most all TTL and many CMOS TTL / BiMOS have a voltage range of 4.75 - 5.25V max and the ram is around the same, I used 5.3V as a trip point. If this turns out to be too sensitive, I can always adjust it later.
Not sure what I'm doing for the 5V power supply yet. Using the original C64 ps enclosure and it's getting very tight, I may be forced to use a switching supply after all.
Similar to the circuit I'm using - www.allaboutcircuits.com/uploads/articles/crowbar-6v.jpg
Finally got it up and running, power supply works great, but I was greeted with this - imgur.com/a/QXeWH9D
So after some research I'm assuming a PLA or Color RAM issue. Possibly one of the standard logic chips if I'm lucky. I noticed the GAL PLA on ebay and realized that I actually have some of those GAL 20V8 chips and a TL866+ programmer, so I just ordered the board to make them from PCB Way which was a lot cheaper. I think troubleshooting is just down to trial and error at this point.
That bowing on the black one, maybe it's just a manufacturing defect because mine already does that and I haven't even opened it yet. (It's going to be my first candidate for a modification like this specifically because I'll feel less guilty if I screw up and damage the already-imperfect case.) I assumed it was brought on by being stored right-side-up in a hot attic for ten years so all the weight was on the thinnest and least rigid surface.
The potted Commodore power supplies were notorious for failing, even back in the early 1980's. Look at any vintage computer magazine for the time and you will find dozens of ads for aftermarket power supplies. The early (1982) power supply for the C-64 P/N 902503-02 is not potted and is easily rebuildable. I buy all of them that I find. They have a better higher rated voltage regulator in them. David Buchan has a good page on rebuilding them.
Edit: That isn't thermal potting compound that Commodore used. It's just epoxy. In my opinion it was two-fold. It prevents users from attempting to service the unit, like they could with the earlier unit either damaging themself or their machine (also sell more supplies) . Secondly, it allows them to simply drop the components in, requiring no mounting hardware saving a few pennies.
The connector for the 1982 power supply is fully populated.
I always chuckle when people say things like: "When these power supplies get old, they can over-volt and damage your computer", because I bought my first C64 in January of 1983 and by the summer of 1984, the power brick had killed it.
Yikes!
the ac line needs to go to the center of fuse holder,that way if the cap gets removed you will not have live power at the opening.
This is very cool. Would it be possible/better to just use an open frame 9vac transformer instead of dismantling the wall wart?
Sure. If it will fit.
That's really helpful thanks! Also do you have the details of the fuse you used?
I think it was either 1.5 or 2amp
I would guess the DC just based on the red and blue. Often the negative of DC is black, but I've also seen a few with blue and a few with green.
Is there a way to rescue old 9V transformer? they usually are good, only the electronic part is prone to fail right?
Sure. If you want to chip away all that epoxy. Not worth the effort I think.
I bet that connector has a little divot on top even if we don't look at it.
So on your meanwell power supply you have an adjustment for the 5 volt rail how much yours is set?? i have the same power supply instead i have the model with screwpost and metal casing? :)
5.1V
@@RetroHackShack i just see in the video :) sorry :)
Retail employee here. I don't recommend putting shrink wrap on wires, as it is untested for amperage. Instead, please use shrink tubing.
Did I say shrink wrap? I am always fighting short circuits between my brain and my mouth. That's why I need the text on the screen to make corrections all the time.
@@RetroHackShack Lol. I may not know much about shrink tubing, but I know a lot about shrink wrap.
Do you have the links to the parts?
I added them to the description. UA-cam would not let me edit the description until after the video went live for some reason.
I still have my C64 but I stopped trying to use it because I suspected the power supply, with the warped case, was the culprit. I still have one or 2 PSUs lurking in storage and I'd rather buy a new one that I have confidence won't fry my dinosaur.
What about the over voltage protection? The datasheet of the Meanwell EPS-15-5 says that the shutdown is at 5.6 ~ 6.75V. That is too much for C64!
I suppose you could add a 5.1V zener diode if you were really worried about that. It is still going to be a lot less than the 11 - 13V that would hit the 5V line in the old power supply. What would you suggest?
@@RetroHackShack SOLVED! After a research - my solution: I put a TVS diode parallel to the 5V output. The 1N5908 is dedicated to the 5 V logic circuit protection (TTL and CMOS technologies).Their low clamping voltage at high current level guarantees excellent protection for sensitive components.
@@RetroHackShack 1N5338B (B is +/-5% of marked Voltage) can absorb 0.93Amps fully "On". At that point there's 6.0Volts across the leads.
Aliexpress step-down converter
I got two original power supplies stil working and supply 5VDC and 9AC but I do not use them anyways.
Yeah. Don't use them. They die suddenly and then you have bigger problems.
#4: Transformer buzz damper during operation
what epoxy are you using ? thanks
Any two part 5 min epoxy should work.
OK Aaron, next rebuild is a Plus/4 power supply. I have one you can borrow to rebuild :D
I have one sitting here next to me already done :) Now I just need a plus 4.
@@RetroHackShack shoot - wish I knew you were lookin, Aaron, I *just* saw one a few days ago for cheap. For the life of me I don't remember the forum though. If I do I'll pass it along.
Why use potting compound?
No screws required to hold components in place.
That's an interesting idea and I am sure that was part of it.
You'll have fun if you ever want to replace caps on that power board you glued in there. I'd imagine you'd have to tear it apart to get it out. If you'd glued in some feet then screwed the board in that would have helped. But I'm not perfect with my projects either. Far from it.
I thought about it, but these meanwell power supplies are good quality and should last a long time. The board will pop out with a little force if I ever need to remove it.
"...By mistake or if I bump it on something."
Uhh... what might be the supposed "difference"?
"Down in the bottom of the top cover..."
* In the _top_ of the top cover.
maybe nice if You save the original 9V~ transformer and just replace the 5V= power supply somehow.
In for a penny in for a pound.
Some power supplies were not potted. The oldest type that I'm lucky enough to have one. I put a step-down regulator from aliexpress inside. No further concerns.
Haha! Those teeth are sharp! 😁
Your "4:00" as you claimed looks to me more like 5:00.
Another home brew power supply.
"Things like... and things like..."?
"The red one is definitely 5V."
Um... they're _both_ 5V (+ and - lines).
Oh shoot, heh, you should've watched your case orientation with respect to the cords and strain-relief boots.
they tried to keep their power supply from being reverse engineered
I bet there's no room for you to put that anywhere without the wires getting in the way even if we don't look.
to stop anyone repairing them so you had to buy a new one and they make more money
STOP SAYING "POTTING COMPOUND", lol