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Commodore C64 Dangerous Wedge PSU Repair
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- Опубликовано: 31 окт 2020
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Fixing a Commodore C64 Wedge PSU. This one had a fault that could destroy a C64, and a surprise in the plug too at the end!
Plan C - C64 PSU (Replace Internals) - • C64 Re-Brick Reloaded ...
#commodore #c64 #repair #psu
Plan C - C64 PSU (Replace Internals) video that I mentioned in this video - ruclips.net/video/lY9kxz0LSyE/видео.html
Didn't realise there was ANY serviceable parts inside a wedge, encouraging to see all the DC circuitry available
Happy to see you are repairing this linear PSU instead of getting a new SMPS like everybody is doing these days. I like the linear PSU much better I have to say, thanks for the video!
Awesome job as per usual and great relaxing Sunday viewing! Thanks very much for the shout out! I really appreciate it. Love the way you re-used the original heatsink! I think you dodged a bullet by not trying to dig out the old regulator from all that epoxy! It is tough as nails and doesn't shatter easily even with a hammer and flat head screwdriver. It also has a nasty habit of sending razor sharp bits flying everywhere!
ps those Traco power regulators do come in a 2 amp version but they are about £10 each plus VAT and postage from Farnell! Ebay does a good line in MP1584 adjustable dc-dc converters that cost about a quid each. Used to use them on drones. The quality varies so it is always worth scoping them but I've had pretty good results so far. They will take anything from 6-36v input and can do about 5v at between 1.5 and 2a with acceptable ripple.
Haha =D Yes, I think it would be better to just replace all the innards like you did - but you know what I am like, I always try to repair the crustiest of things ;) I did (off camera) try a much beefier DC 2 DC, but the voltage drop is still a problem. I used a 3A one, still drops to around 4.74v because of the cable length and resistance. But I haven't tried an adjustable one - that would do the trick!
Thanks for the vid Chris. I’ve a faulty one of those wedge supplies in a drawer somewhere. I’ve been thinking about doing a repair job on it. Especially after Commodore Lad talked through basically this process on twitter. Great to see it done.
Thanks for the tutorial on repairing the wedge power supply Gadget U.K. as I got one runny 5.2V D.C. from my multimeter cheers.
remember these on my old 64 in the 80’s always thought it was a perfect angle for keeping my foot warm - the amiga one took that luxury away but it was 16bit!
I thought I was the only one who did this :D
I've replaced the 7805 regulators in all of my wedge shaped PSUs with a small switching regulator board that I epoxied into the little empty compartment under the rectifier board. You have to bridge these resistors (if present, not all PSUs have them) to provide a proper ground for the regulator board. But apart from that, it works fine for me.
That said, I've had a failure on one of these PSUs lately, where I left it running unattended for maybe 30 min. and when I came back, the case was bursted open and the epoxy that contains the transformer turned into a gluey mass that was slowly creeping out of the hole in the case. It still worked fine though...:-)
It turned out to be a kind of short in the transformer, but nothing serious enough to blow the fuse...it just heated up the transformer so that the innards turned into a mush.
Ouch, that's a nasty failure!!!
Do the switching regs add any more noise to the supply voltage?
@@tahustvedt I guess that in theory they might but I haven't had any issues of any kind with them. It might depend on the regulator though.
Nice job. I have one of these so will be testing it out.
Another fine repair by Gadget. You saved that C64 from all those extra Volts. Another to cross off your list, well done Chris
Thanks 👍
Love ur vids mate always detailed and informative.
One thing you can do if you need more amperage (or less heat) out of a regulator is to just put two of them in parallel. Works great with 7805.
I've done that in the past and found that it can cause issues - where one regulator fights with the other as they both try to compensate for level changes.
@@GadgetUK164 I'd be interested in knowing how you can tell such a thing -- are you just experiencing noisier rails or brown outs?
Theoretically, I'd think you could fight it with decoupling caps on the input and output stages. Both a small ceramic for high frequency changes, and a larger polarized electrolytic for slow drifting changes. (So four caps total, two on the input and two on the output.)
If the signal is still noisy, try adding a 5v or a 5.1v zener on the output (in reverse polarity; so that it caps the voltage at the breakdown level).
You are more brave than me! I do all of my own work these days but I still won't touch these PSU's. But that is mostly because Ray Carlson lives a few states over from where I am at and he's an awesome guy. So I throw money his way whenever I need an Commodore/Amiga PSU. Then I put the OEM PSU's on the and just mark them as never use.
I'm in the UK and just bought one from him
Thanks a lot for this video! I got a broken plus 4 PSU right now. Same problem with over voltage. I want to remove the epoxy, and all the old (garbage) electronics out and built it with new parts. I am gonna check the other video! Thanks a lot for your contribution to retro computing repairs!
It’s the same PSU, only has a different plug
And subscribed!
My USA C64 had been getting a hot supper from the old power brick that had failed in this way. It came to me with a bad KERNAL ROM, and then never worked quite right when I replaced it. Turns out that "+5" had become more like +12, and the only reason that every chip hadn't spontaneously combusted was because it had gone down to ~+6.5 when the voltage drops were done.
The way I found out was that one day after running the Dead Test cart and having that fail at random, I felt a massive wave of heat from the entire mainboard. I busted out my thermal imager and found nasty things like SID running at some awful temp like +85C, and that's when I decided to start taking voltage measurements.
I'm very lucky that the rare and expensive chips still work after I made a new power supply that supplied the proper voltages. I did lose one 6526 to this mess, but I had a spare parts board with a good one. All good now!
It occurred to me that - before you clipped the leads off the old regulator - you could wire the two outer pins directly to the 240v mains and blow the thing right clear out of the epoxy! 🧨 Of course, put it behind a blast shield of some sort, or get a really long extension cord, put the thing out on the patio, the plug it in indoors! Make sure to save the video and post it here on your channel! 😊
Haha, nice idea :o)
Great vid, oh dear the sniffing of crusty caps lol.
I immediately felt the same about why they didn't clip the leads, unless it was just laziness. I've never seen a PCB with such long leads left before.
Every time i see some one on social media about a c64/Amiga/oldsystem i tell them to replace the PSU and not boot up their system. Well some people dont listen en told me then afterwards that i was right..... yeah.
Another great video :)
Some people just dont understand things like this.
Very enjoyable Chris :-)
Thanks Vince =D
Still laughing so hard at that wrap around wire instead of the proper fuse , lol So Funny
Interesting to repair a power supply with so much epoxy in it. Thanks for posting!
Thanks for watching! And supporting me =D
My dad used to repair C64's when I was a kid (late 80s early 90s in the US) and step one of any repair was to throw out the power supply (even if it was good) - even then while the machines were still being sold they were notorious for failing in a way where they'd provide too much voltage and start blowing up chips.
Measure the input voltage of the 7805!!! 13V DC!!! I am guessing the engineers knew OHM`s law. :)
Probably production decided to have 2x 10V AC transformer. (8V drop on the 7805 will heat it constantly.)
Better to change it to a switching 5V AC-DC power supply. They do not heat even on higher input voltage.
But the question is the brown out.
Also old linear regulators has larger dropout voltage. But still the 13V DC input is very high for a 7805.
With switching power supplies has a maximum filter capacitance value. Follow the manufacturer recommendation.
And the switching regulator`s brown out can cause issues. I would not use switching regulator for 12V because of this reason. Might you would get bang sound when you turn the computer OFF. (The amp IC turns OFF slowly)
I can't believe someone stuck a piece of wire across the fuse holder!
Haha =D
New heart for C64. 💚
It is as easy as replacing the board with a Meanwell switching regulator 5V2A, those are like 5x2,5cm and will fit.
I suspect, if that's doing DC 2 DC stuff (ie. PWM controlled DC generation), the noise produced would affect the video and or audio on the C64. Others (and me) have tried these DC2DC devices and found they produce noise!
@@GadgetUK164 It is AC-DC, and probably it will be noisy. On the otherhand, the output of a C64 is trash anyway, and if some noise is added one probably won't see/hear the difference.
I'll go the easiest way, and just add a safety diode to the C64 main board. I can't get the original brick open.
C64 power supplies are getting awfully old. I stripped down two PC PSU for the metal case and put in a 2A 9VAC xfmr and a 2 amp 5VDC module and wired in the existing cable. Good video for restoration purposes
Don’t turn up the heat on your iron; use a bigger tip! I pretty much exclusively use a big “hoof” tip; but a “screwdriver” or “chisel” tip works well also. The bigger the tip, the more heat is in it and can flow thru it; and the more contact area you have, the better the heat transfer.
I notice later in the video the battery had been changed and wonder if you tried measuring with a good battery in your meter and comparing when you had the weak battery in cos the measurement reference goes out of tolerance when the battery is low.
I had a good 9v battery that measured 12v on my old fluke 77 until I replaced the battery 😂
The regulator still measured like 7v - I checked it on the bench PSU later! The battery in a multimeter can do that though!
Am getting 5.3 volts from my c64 wedge type psu so am looking to do the same as in your video here, were do you buy the voltage regulator for them from?
5.3V is actually correct! The regulators are tweaked with resistors to provide that voltage, to take into account voltage drop on the cable lenght. bwack has some open source PCBs I think - perhaps on PCB Way or Dirty PCBs - worth a look.
4.75-5.25V is the spec for TTL voltage. But 4.75 was really on low end. :-)
Hi. Do you have a video about building a saver?
Also, did you try heating the black resin?
Having a dead component stuck in the PSU triggers my OCD!
I haven't built one yet, I may do though! That black resin I think is perhaps chemically set - I am not sure it would melt again. Please let me know if you find otherwise!
Very interesting
3:19 You have a quite interesting de-solder pump. Never saw that type (with silicon tip I presume?) Can you tell me what brand / type it is?
It's an "Engineer" desolder pump - came from Amazon!
Sniffing old caps is a good way to detect leakage. =)! Would you recommend a L78S05CV. I think that C64 is rated about 1.5 - 1.7 A. Btw what is a 5v saver that you recommend? (fuse?)
Yes, the CV one is the better choice. The 5v saver - just search my videos for 5v saver, you will see the ones I got from bwack on RUclips. It sits inline with the power connector and cuts the power if 5v goes above 5.3v.
@@GadgetUK164 I already found and watch that video.! Cheers!
I've said it before, but I use acetone to weld ABS parts together. ;)
I've tried acetone - just doesn't seem to do anything at all on the plastics I've tried it with - like putting water on it!?!?
If you plan on using the supply, you should really take the transformer out completely and just replace the whole insides with modern kit. The low energy components aren't too bad when they fail, but if there is a problem in the transformer block you can end up with high voltage frying your computer...
That seems quite unlikely though. Wire-wound transformers are robust things, the only way to kill them is usually a massive short on the secondary and if your C64 has got that massive a short you've got other problems. Those two caps and the voltage regulator are the only parts in the PSU I'd reasonably expect to fail.
I have a micro mate power supply, It was recapped and it'd a solid beast of a wedge. But i do get audible hum on the audio from it. Would a 5 and 12volt saved neutralise this?
The hum may be coming from the transformer, or noise from somewhere else on the PSU. A 5v saver wouldn't solve that problem!
@@GadgetUK164 Thank you for the information. I assume it just needs some sort of isolation? As i said, it's a micromate, looks just like the one in your video, but it is user serviceable It's had new caps. Is there a suggestion you might have?
Change that uk plug btw
The live and neutral should be sleeved tbh
Yeah, I did mention that in the video! ;)
Always a good time ey? Had an A4000 question. I have one I've been working on that the serial output has corruption but its always the same (same places). And the video is solid colors (NOT ERROR COLORS, this is important to note). DiagROM doesn't have any info and I've been talking to John and a few other Amiga techs (Tristan, Peter M, Keir). I'm at a lose, getting ready to just rebuild it on a new board from my friend Acill. Any advice? Yes, checked under the SIMMs, removed chips near the battery. Nothing obvious or related to the video. Also chipmem seems fine.
Where in the serial output is the corruption - that will be a huge clue! I suspect you've got a clock problem somewhere.
I probably would have replaced the PCB with a LM2596 board. Available on eBay for under a buck.
Yes i agree these are way more efficient than 7805 regulators.
I used an UBEC modules in my module but lm2596 is another solution.
Hi Gadgetuk164 Ave left you a message on the Amiga english board :)
1) bin internals (and external casing hehe)
2) replace with modern version
I just bought a c64c and dare not turn it on now until i have at least a new PSU and voltage saver lead...did a search on c64 power supply issues and the results were horrific...I have a couple of amiga500s as well...are they affected as well by this over voltage issue.?.
Amiga PSUs can and do fail, but tbh - if they are re-capped, you tend to rarely have an issue with them vs the C64 ones...
@@GadgetUK164 I just bought a voltage saver for my c64c...what is your opinion of them.?
That replacement 7805 looks kinda weird. It has that super thin mounting tab. BTW. I wonder if modifying the computer itself with 5W 5.6V Zener diode and a fuse could save it from overvoltage PSU fault (adding reverse polarity protection as a bonus). The theory is that when voltage rises over 5.6V (maybe a little bit more for higher current) Zener diode would start conducting burning the fuse at the same time and saving the rest of the board. Cheap Zener diodes from 1N53xx series are rated for 180W surges. That would be more than enough to blow something like 3A fuse.
Yes, you're talking about a crowbar circuit there. People do the same sort of thing in other PSU's, or use an SCR to achieve the crowbar part. That would work! I just used the 5v saver from bwack though - cuts power rather than force blowing a fuse.
If the components had their own tailored power cold you remove the resistors?
The resistors are used to increase the 5v to ~5.3v. WIthout them the 7805 just outputs 5v, which with the voltage drop on the cable results in 4.7 to 4.8v =/
What thermal paste did you use on the voltage regulator?
Just the same type used on transistors and regulators. You could go fancy and use arctic silver or some other super thermal conductive paste.
4:18 Ghost n Goblins FTW!!!!
Easiest way is to replace the regulator with an off the shelf UBEC
You really need one that's adjustable though, to set to more than 5v. Otherwise you just get voltage drop.
When I got a C64 power brick that output >7V, I just cut out the original 7805, put some thermal compount on a new one and stuck it in between the case plastic and the heatsink. The case was elastic enough to push the 7805 against the heatsink. It turned out to be a lot more reliable than I thought it would be...
And when I tested a C64 Wedge PSU that I haven't used in a long time, I got 5.37V and thought hm - a bit high, but probably OK. The voltage wouldn't change on load, still 5.37V. Inside the C64 I got 5.14V well within the TTL comfort zone so I'm gonna leave it for now. Now I know that there are resistors in the PSU extra for compensating the wire resistance!
Do you do all your repairs on the ground?
Pretty much!
@@GadgetUK164 does the missus dislike the idea of having a desk in the conservatory? 😁
If you ran your device from a battery, could you remove all the caps?
You wouldn't need as many caps, but it would probably be very stable without the main smoothing caps if running from a battery that can provide lots of current. The caps also help filter out noise in general though.
Im so glad I splashed out on a Ray power supply for my C64 an Amiga. All of my consoles use modern PSUs now.
Starforce Nova in the background :-)
It was Ghosts n Goblins!!!
@@GadgetUK164 Ah, okay. Sounds a litle bit similar for me... haven't played that games for a long time.
Kevin Ottum (Ottumland I believe) has the best 'Rebrick Videos imho..have a look at his channel if you have a moment. -Mark.
Hi Chris, I have 'fixed' at least 20 of these wedge type power supplies with a "3A Switch Mode Ubec Output 5V" from aliexpress. They don't cost that much on aliexpress and work perfectly. There is a good 'how to' on lemon64 www.lemon64.com/forum/viewtopic.php?t=48451
Maybe a good option for next time...
"I always sniff these things"...........ok!
Yeah leaking caps often smell fishy jsyk.
@@donnied8127 No the chemical literally smells like fish. :|
:o)
I'm partial to the 5V 3A switching regulators from EZSBC: www.ezsbc.com/product/psu5-2/
They are a drop in replacement for a TO-220 regulator and they work great. Not adjustable (maybe so if modded I guess), but I've used them in my Aquarius and it's a straight up replacement with no heat sink required.
You need more than 5v though due to the voltage drop. I guess with a better and shorter cable 5v DC2DC would work?!?
@@GadgetUK164 I suppose, but the attraction of reusing an old supply case is the retro look. Changing out the cable might diminish that.
But these are perfect for replacing the regulator in a Speccys, C64s, etc. Anything that uses a 7805, and no need for a heatsink. :)
They make an adjustable 1A regulator: www.ezsbc.com/product/psu2-adj/
Looks like a tall mouse heh. What was the whole epoxy encasement movement, a bid to make electronics you can't fix? Ah no wonder there was a rattle. ;)
I wrote a guide in Dutch about fixing/future proofing the Ismet Wedge PSU:
www.freepascal.org/~daniel/c64_wigvoeding_revisie.pdf
A weakness of your repair is that you are using the original diodes. These are 1A diodes for a 1.5A power supply and generate a lot heat, leave burn marks into the PCB and can fail (there is a photo of diode failure in my guide). Therefore I believe you should throw out the entire rectifier board and replace it with a new one, preferably with a switching regulator so the heat problems of the original design (which is what causes the regulator to fail) are gone.
Why am I not surprised the really crappy C64 PSU's were ISMET :)
this is 3 years old so I just hope you learned to lose the annoying 70s porn soundtrack
I would not repair such a thing. Just buy a modern one.