C64 NTSC Video

[Czar_roland]

Howdy everyone. I've been working on my c64 breadbox (NTSC) on and off for about a year. I recapped it about a year ago to resolve some issues with the picture being washed out. As it turns out this was needed, but I was too late. There were traces burned off from leaky caps. I kept it as it was until a few weeks ago when I ordered a bypass board from Video Game Perfection.

 

Today after reinstalling everything I had video but it was only black and white. The monitor that I am using is a known good 1702. I tested it with a Master System when stuff was working for the C64 and it worked fine with that hooked up. 

 

I figured I had a bad solder joint but wanted to try composite video anyway. I grabbed the wrong cable (Genesis 1) and plugged it in. After pulling it out, realizing the error, and then plugging the svideo cable back in I no longer have video on the machine. Any help with be appreciated. And yes, I feel dumb.

Edited February 18, 2021 by Czar_roland

[carlsson]

I know as far as composite video on the MD1 = audio on the C64 and that audio on the MD1 = luma signal on the C64, which explains the black and white image. Ground should be the same, so I don't know what could have happened unless you have a short between more pins in the DIN connector. Also I'm not familiar with the bypass board you mentioned. Did you plug in the S-Video cable in the right jacks on the 1702 and have flipped the switch to that input mode?

[bluejay]

From what I can gather you shouldn't be able to plug in a Genesis cable into a C64 or vice versa due to a slight difference between the placement of the 8 pins. Regardless, plugging in the wrong video cable can't have killed the computer, so maybe there's another issue.

 

If you are using a proper LCA cable, keep in mind you have to plug each of the RCA connectors to the back of the 1702. If you've been plugging in the yellow RCA connector into the composite input that is on the front of the 1702, that might explain why you saw no color, as the yellow connector only outputs luminance.

[carlsson]

Both MD1 (Genesis 1) and C64 use a 262 degree 8-pin DIN if you want full RGB respective S-Video output. In both cases a standard 5-pin DIN is sufficient to get composite video, though with different pinouts as noted.

[Czar_roland]

I am using a proper LCA cable into the back of the monitor with the switch set to rear. All I can think is that something shorted between plugging in the LCA and plugging in the MD1 composite. I did see a small screwdriver (with metal body) next to the board. Maybe that touched something and shorted something out. I have a multimeter but have never used it for anything other than testing caps or power supplies. I guess the next step is to check each circuit. Thanks everyone.