Color Classic Analog 640x480 VGA mod and recap questions

[JohnnyPhantom]

Hey Everyone,
I recently got a color classic off Facebook a few days ago. It has signs of life but didn’t work as it should when powered on (no video and static or garbled chime) I ordered a cap kit for the logic board and analog board and figured I’d start there. As I was recalling the analog board I came up with a few concerns. One is on the console5 kit, CV21 is a 100uf 25v cap (which is also what it says on recap a Mac) But the one I removed was 100uf 35v. I know you can go upwards on voltages when changing caps, but this is going down by 10v so that’s got my curious. The other is is that it looks like the previous owner attempted the VGA 640x480 mod, but it looks wrong to me. They had isolated pin 8 from 9 but then reconnected it with a jumper wire, maybe they tried to undo it? I then disconnected it and noticed that pin 8 is isolated but pins 9, 10, and 12 do beep when I do a conductivity test in them (pretty sure that’s the correct pins I’m referencing, I circled the 3 in red in the photos attached to this post) is that correct? I doubt it, since if that was the case, then why would you need to cut pin 8? I also see a yellow jumper on pin 20 on the cart connector area but no traces cut. So looks like a few things aren’t matching up. I have all the caps replaced now, but don’t want to test and power up the machine with these questions unanswered. What should I do or check?

Thanks in advance everyone!

 

[ObeyDaleks]

I definitely wouldn’t go down in voltage spec on that cap. That could lead to problems. Looks to me like the board had the voltage mod done but then it was reversed by bridging the pins (in your last picture). I have no idea what the jumper is for between pins 18 and 20. That doesn’t seem right. I would also check your main ribbon to see if it was modified. Some people do the VGA sense mod by cutting/splicing wires on the ribbon cable. You may have to do some very thorough inspection to figure out what else they modified. It’s possible that the board failed due to some botched mods and they tried to fix it by reversing the voltage mod - cuz why else would they bridge those pins?

 

[JohnnyPhantom]

I definitely wouldn’t go down in voltage spec on that cap. That could lead to problems. Looks to me like the board had the voltage mod done but then it was reversed by bridging the pins (in your last picture). I have no idea what the jumper is for between pins 18 and 20. That doesn’t seem right. I would also check your main ribbon to see if it was modified. Some people do the VGA sense mod by cutting/splicing wires on the ribbon cable. You may have to do some very thorough inspection to figure out what else they modified. It’s possible that the board failed due to some botched mods and they tried to fix it by reversing the voltage mod - cuz why else would they bridge those pins?

That's a good point. I figured since it powered on before, maybe it'll power on just the same with the new caps. so I put it back in and powered it on, and magic smoke... boooo.. I looked closely everywhere on the logic and analog board, but couldn't see where it came from. So I'll be diving deeper They also changed 2 diodes into 1. I was emailing back and forth with Thomas from Amiga of Rochester. if we can't figure it out via our email correspondence, I'll mail it in for repair. I know this machine wasn't working when I got it and the seller was just gonna gut it and scrap it, doing my best to save it from the bin.

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