Awesome, thank you so muchHi RenierD, sure i have a pdf for the GP-13 board but i cant upload it in here (says file is too large 1mb!), i made a google drive link to it: GP-13 cpu schematics
i hope its useful to you,
BTW whats wrong with your board, am still trying to fix the one i have and am almost there. you can share with me your progress i would be glad to help you out.
good luck
Mine (GP-11) is missing the blue channel. It seems like a common problem, with various potential problem areas.
Tracing backwards from the Blue JAMMA pin, the filter IO shows continuity. I'm currently investigating TR9 and TR10 - blue toggles frantically high and low at R18. Red and green (R23 and R28 ) just toggles high (or low, can't remember).
This is now all on the Mother PCB
What is funny (to me) is that RGB toggles fine as it leaves the CPU board through the big white connector, but when Blue it reaches R18 it starts to toggle differently.
Does it mean there might be a short somewhere? But it there was a short it would either toggle high or toggle low. Or can it be that there is a faulty component?
I managed swob out TR10, but didn't get to TR9, yet.