Commodore 64 Issue

[wmmullaney]

Hi everyone, today (funny day for a yard sale) bought a 64, 1541, and power supply all in working condition for $4, awesome steal.

Anyway, when it's switched on, the video syncs, but flickers very badly. I loaded some music off the disk drive, and it played chariots of fire fine. I also reseated all the chips to no avail. Does anyone know whats wrong here?

I have another 64 I can swap chips with, but I'd rather not if anyone has an answer.

Thanks!

 

[Dave Farquhar]

It's been years since I've troubleshot a 64, but have you tried a known-good power supply by any chance?

 

[wmmullaney]

Thanks for the reply Dave, that didn't seem to help any.

 

[jthiemann]

Anyway, when it's switched on, the video syncs, but flickers very badly.

Great steal, I'd agree! I wouldn't swap chips yet either, that doesn't seem to be the issue. Are you hooked up to a monitor or a TV via the modulator? Is the flicker steady all the time, or is it intermittent loss of picture?

Either way with that vintage gear I would always check caps first. Are any swollen or even leaking? If the flicker is intermittent I would check the connectors. Cold joints? Or even simply dirty contacts?

 

[wmmullaney]

Hi, the flicker is very consistent.
The computer was pretty dirty on the outside, but after a good cleaning it now looks good as new. The insides also look pristine, the caps also look fine; which ones go to the video circuit? Is the VIC chip at fault?

I'm actually using composite video and audio from the din port, I'll try the modulator, but that involves pulling out the rf switch and moving the whole works downstairs. It's hooked up to my portable dvd player that serves as a portable monitor due to the drive dying. It works flawlessly (colors are slightly off) with the other 64 and 128, and also with the apples. I can get a video of the issue if it would help.

Again, thanks!