Commodore 128D to C64 PSU Mod

Heather,

I had a fright this Friday night. On Friday while accessing the Madword BBS the 64 screen went blank. The 64's led started throbbing flashing and both drive lights started flashing like crazy. I noticed the Power supply was also doing the same thing. I powered down the system and let it sit for a few. Started it back up and the same thing happened.

Took apart the power supply and the large 220uf 250v capacitor had leaked out onto the board. That cap was the only one I had not replaced. I found a local store that had the cap and replaced it. Everything is working fine and the computer and disk drive did not seemed to have been damaged.


And a second note. On another one of the power supplies that I have converted I have a strange issue with the power supply turning on. I like to use the switch on the power supply to turn on the 64 and 41-II. This is to save the switches on the Commodore's. They are left with the their switches on. On one of the conversions when you flip the switch to the power supply neither comes on. If you turn the switch off and back on both power up. Also if you power up the PS and the computer and drive does not come on if you power off either of the devices the other will power up and you can then turn back on the other. All the caps have been changed on the board. I have tried different cables to the drive and computer and even switched out the new transformers on the board. Once running there does not seem to be any problems. Very strange and I would like to know why.
 
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I'm very happy to hear the capacitor leak didn't cause any damage. There's always a chance that an old capacitor will do that, even if it's never been used. :(

I am still only powering the C64 from my power supply so I haven't experienced any issues while using the PSU switch. One thing to remember is that each device is probably drawing a bit more power when they are first turned on compared with the running draw. It could be that the PSU cannot handle the needs of all the devices when switching all of them on at the same time. You could easily add a secondary switch on front of the PSU that is attached to the power cable for the 41-II.

Please let me know what you find. :)

Heather
 
I believe it also occurred even when I was only just powering on the 64. I wish there was a part I could test to see if it was bad.
 
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