I am in the process of doing the VGA mod on my CC. I have an LC 575 motherboard that I want to use as well.
First I isolated pin 8 with a dremmel type tool. Then I soldered a wire from pin 8 to pin 12.
I then Isolated pin 20 on the analog board by dremmeling the pin in this manner:
pin
22 20 18
21 | 19
connector
^
| I cut right there, figuring it would be isolated
I then dremmeled pin 25 at the bottom (towards the connector) to isolate that (or so I assumed). I then soldered pin 20 to (d'oh) pin 26. I got video, but it was really messed up, and the OS 7.6 boot CD gave me a bomb (bus error) with the LC 575 motherboard. Noticing I didn't solder pin 20 to pin 24 I dove in again to fix that.
I then soldered pin 20 to pin 24 with some wire and put everything back together. I now have NO video...
Here's what I thought might have caused it:
1) pin 25 is not isolated because I only isolated it on the bottom, not the bottom and top as pictured here:
http://www.colourclassicfaq.com/img/connector.jpg
2) I messed up the solder joints surrounding pin 26 through pin 18 as I did get solder very hot around there. I didn't have the right tip on the first time. I DID find my fine tip though...
3) I broke the CRT in some manner...
I've checked to make sure I plugged everything in. I just don't know where else to check, or how to check if I've killed my color classic.
Any tips or advice is appreciated!
Thanks,
John
looks like my text diagram didn't work right. I will post pics tonight, but I isolated pin 20 by dremmeling straight down to the connector if that makes sense.
I should also note my board does NOT have J78/79 on it.