Background: At my home, occasionally on older systems and old Atari's that when I power up, the screen has a wavy horizontal line of variable intensity, typically about 1/8 of the screen that slowly rolls/scrolls upward continuously. Inparticular, I had noticed it with a gamecube using a 3rd party power supply, (x2) which corrected after getting a Nintendo branded power supply. I found some information on this and maybe I have a ground loop problem? Most information about ground loops is in regards to sound systems and not video interference. Other electronics in the house seem to work fine, (no sound hums) as far as I can tell otherwise and I have just been living with it.
I had picked up a couple of C128 locally both in unknown working conditions and both turned out to have with nonworking, power supplies, capacitor stuff and/or brown goo/glue all over the place. There are a multitude of Commodore 64 DIY power supply replacement builds out (see youtube) so I made a couple of DYI power supplies with 9 volt AC wall warts and one with a 5 volt switching supply the other with a 5 volt wall wart housed in the original power supply. I had been using both of these machines for a year or so without issue aside from the scrolling interference., usually on an LCD with S-video.
Soon I located a Commodore monitor (then another, and to quote Seinfeld, they are spectacular) which when the 128's were hooked up initially had very severe video interference....then faint sound, then no sound, noticed over the course of seconds to maybe minutes with loading. Both SIDS are gone. Anyway, I ordered a Keelog power supply replacement and there is no video interference (when using only one video output) and replaced one SID with a Nano Swin SID and have another SID replacement ordered from BackBit which hasn't arrived yet.
My theory is that DIY power supplies just don't have the same layer of protection a professionally done supply provides for these older electronics...especially with what seems to be a ground loop that varies in my house. As I have eyes but little electronics knowledge , when you construct these modern DIY replacements, there are none of the large value capacitors or filters you see in the original supplies.....is there any way to place just some high value capacitors in line on the high voltage side to prevent incoming fluctuations? I suspect its more complicated than that.
Sorry for the wordiness, but , if you have any hesitancy, just get a well built supply from Keelog or similar.....these parts are just too expensive to replace or not available.
I had picked up a couple of C128 locally both in unknown working conditions and both turned out to have with nonworking, power supplies, capacitor stuff and/or brown goo/glue all over the place. There are a multitude of Commodore 64 DIY power supply replacement builds out (see youtube) so I made a couple of DYI power supplies with 9 volt AC wall warts and one with a 5 volt switching supply the other with a 5 volt wall wart housed in the original power supply. I had been using both of these machines for a year or so without issue aside from the scrolling interference., usually on an LCD with S-video.
Soon I located a Commodore monitor (then another, and to quote Seinfeld, they are spectacular) which when the 128's were hooked up initially had very severe video interference....then faint sound, then no sound, noticed over the course of seconds to maybe minutes with loading. Both SIDS are gone. Anyway, I ordered a Keelog power supply replacement and there is no video interference (when using only one video output) and replaced one SID with a Nano Swin SID and have another SID replacement ordered from BackBit which hasn't arrived yet.
My theory is that DIY power supplies just don't have the same layer of protection a professionally done supply provides for these older electronics...especially with what seems to be a ground loop that varies in my house. As I have eyes but little electronics knowledge , when you construct these modern DIY replacements, there are none of the large value capacitors or filters you see in the original supplies.....is there any way to place just some high value capacitors in line on the high voltage side to prevent incoming fluctuations? I suspect its more complicated than that.
Sorry for the wordiness, but , if you have any hesitancy, just get a well built supply from Keelog or similar.....these parts are just too expensive to replace or not available.
