C64 power supply testing / rebuilding

[ral-clan]

Hi folks,

Although I'm mostly a VIC-20 fan, I do have one sad, old C64 which died fairly quickly after I acquired it. I'm pretty sure one or more of the RAM chips has gone bad, based on the symptoms. I know it's not a problem with the PLA chip.

So, I've ordered some replacement RAM chips.

I've heard that the C64 RAM can be killed easily with a failing power supply. I have about 5 spare C64 power supplies, and several of them test good for voltage with a multi-meter (not under load - I don't know how I could test them under load). I've heard that if there is a ripple on the power supply it can also kill a RAM chip. I don't know how to test for ripple, I don't have an oscilloscope, and am not even sure if that's the tool for the job.

I've also heard of some people building their own power supplies out of old laptop power supplies and a 9V wall wart (or several wall warts). Ray Carlsen even did it this way at one time:

http://personalpages.tds.net/~rcarlsen/ ... S%20PS.jpg

I am pretty sure I can build one like shown in this picture. Just one question - is modern 5v power supply (like that provided by a laptop supply) much more reliable than the old original C64 one in terms of its power regulation/fail-safe features? If it's no better than I won't bother.

I know Ray Carlsen makes new power supplies, which are amazing, but since I will rarely ever use this C64, I don't want to play nearly $100 for a deluxe power supply.

So I guess what I'm asking is has anyone ever built their own C64 power supply - can you give me tips or point me to information online? I have lots of experience with soldering, tearing electrical equipment apart, rebuilding, replacing components, using a multi-meter to test for voltage, etc. I am not an electrician/electronics expert (i.e. I don't know how to "do the math", but I follow instructions well).

Or maybe it would be better to continue to use one of my original C64 power supplies if I can make sure it is functioning well? Or all all these going to fail soon, causing damage to the C64?

I am in N. America 110v/60Hz land and I am pretty sure all the C64 power supplies I have are the kind that are solid poured epoxy bricks inside the plastic case.

Thanks

[ral-clan]

I found this helpful article:

http://dannygalaga.com/c64.html

Still would like to hear from anyone who has tried this (or not).

[RobertBe]

Or maybe it would be better to continue to use one of my original C64 power supplies if I can make sure it is functioning well? Or all all these going to fail soon, causing damage to the C64?

If you wish to use an original C64 p.s., I'd strongly advise you to buy one of Ray Carlsen's Computer Savers.

A cheaper solution,
Robert Bernardo
Fresno Commodore User Group
http://www.dickestel.com/fcug.htm
July 18-19 Commodore Vegas Expo v11 -
http://www.portcommodore.com/commvex