C64 power supply. Do NOT use 1 unless you check the output.

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Re: C64 power supply. Do NOT use 1 unless you check the outp

Postby nzoomed on Tue Oct 25, 2016 8:58 am

mons2b wrote:Ill put you as the first to try one NZ Zoomed. I went through some old C64s i have and one breadbin had a chip hot enough to fry an egg. I think a victim of a bad power supply. I plan to give one Breadbin the full delux spa treatment with new caps and heatsinks everywhere. I will also put a new cap in the one C64 power supply Ive found that can be repaired. The regulator 7812 in the power supply is attached to a huge heatsink so it should be ok but its more than 30 years old so a new one might be good especially as I can get to it.

Something I belatedly realized.. The 1541-II disc drives have a very similar power supply that is also usually sealed and could also be now putting too much voltage into your disc drive. Those who use those SD card replacements no worries for you. But if youre like me and you like using a real drive check that power supply too. On the large original drives the power supply is INSIDE the drive. I am going to try to look inside the one i have at some point and see what voltage its feeding out.

All power supplies should be checked really at this point. So your Vic 20 , c16, plus 4 etc. Be careful with mains voltages.


Thanks, i look forward to testing it :)

Yes your right about the 1541-II drives, they did have similar issues with their power supplies.

Would be great if someone could produce a replica C64 power brick one day, that would be the ultimate replacement!
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Re: C64 power supply. Do NOT use 1 unless you check the outp

Postby mons2b on Tue Oct 25, 2016 6:57 pm

I totally agree. It would actually be possible to gut a original supply and squeeze a modern switchmode setup in there I recon but the trouble is that power supplies are mired in so much regulation and rules. Theres always a way though. Could get a chinese company to make ones in the same square size casing to the mm then you can remove the chinese case and put the insides in your own horrible carbonite box. What you do at home is upto you. That would be one way to do it.

The power supply i found would be a much better one to get duplicated though. No epoxy and good open venting. Probably why its still only just out of spec. Ive realised im going to need so many more regulators for the disk drives etc. I have some other computers like ones that are very important to me for sentimental reasons I want to filter the psu output on.

20161025_215002.jpg
Looks like the best C64 original PSU.
20161025_215002.jpg (844.09 KiB) Viewed 1966 times


20161025_215012.jpg
20161025_215012.jpg (1.1 MiB) Viewed 1966 times
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Re: C64 power supply. Do NOT use 1 unless you check the outp

Postby nzoomed on Tue Oct 25, 2016 10:03 pm

wow, ive never seen one of those, and it appears it has screws, so the whole thing can be taken apart and have new regulators and caps installed :)
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Re: C64 power supply. Do NOT use 1 unless you check the outp

Postby mons2b on Mon Oct 31, 2016 9:34 pm

While testing tonight I found my C64 Bread bin will work on 4.65 volts.. :). I have not tried this on a C64C yet. At this voltage the ICs will run cooler. Results may vary between machines but I thought it was worth sharing.
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Re: C64 power supply. Do NOT use 1 unless you check the outp

Postby nzoomed on Tue Nov 01, 2016 1:40 pm

mons2b wrote:While testing tonight I found my C64 Bread bin will work on 4.65 volts.. :). I have not tried this on a C64C yet. At this voltage the ICs will run cooler. Results may vary between machines but I thought it was worth sharing.

You could always add a voltage selector for switching between models, if the demands are different, either way, using the lowest voltage required to run stable is a good idea.
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Re: C64 power supply. Do NOT use 1 unless you check the outp

Postby mons2b on Thu Nov 03, 2016 9:31 pm

Yes true. It is relatively spacious so I put a regulator board inside it. A real test for the lower voltage will be a stress test with a disk drive game or something like that. Ill try that sometime. I think the epoxy psu's use a transistor arrangement rather than a 7812 regulator IC like this one has. I asked my father who is more experienced than I am with electronics having spent his working life involved with it about the transistorized PSU editions. He thought they would be the ones more likely to go bad and feed out high voltages than one with the regulator IC. Back in the 80s transistors would have been cheaper than a 7812 he also said.
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Re: C64 power supply. Do NOT use 1 unless you check the outp

Postby mons2b on Wed Nov 09, 2016 8:36 pm

FYI. I'm still waiting on parts deliveries. Keeping it cheap means its taking time getting the bits and pieces.
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Re: C64 power supply. Do NOT use 1 unless you check the outp

Postby nzoomed on Thu Nov 10, 2016 9:04 am

mons2b wrote:FYI. I'm still waiting on parts deliveries. Keeping it cheap means its taking time getting the bits and pieces.

OK, its all good, I will still be here waiting :)
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Re: C64 power supply. Do NOT use 1 unless you check the outp

Postby nzoomed on Wed Nov 16, 2016 8:53 pm

I realised that my multimeter battery was actually getting low and after testing the voltage again with a new battery, its reading only 4.5VDC on my c64, so this is a bit of a relief!

Still nice reassurance though to have some form of protection. :)
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Re: C64 power supply. Do NOT use 1 unless you check the outp

Postby nzoomed on Thu Dec 15, 2016 1:00 pm

bumping for mons2b.
This forum is about to be taken down...
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