Fixed: TruboGrafx-16
Symptom: Dead. Only gives light blue screen
There is a definite lack of deep level hardware information on the web for this console. Thanks to this, I worked backwards and pinned out the CPU a bit (address, data, power, reset, clock) and the HuCard socket from the pinouts on the Work SRAM IC.
Checked the reset line and it wasn't being held low long enough. Replaced the capacitor on the RC network feeding the reset line. Reset was working better but was not the cause of the problem.
Found a bad trace on address line A2. Patched that but was getting strange signals on the SRAM with the logic probe. Replaced the IC. Signals were better looking but system was still not booting. Cleaned the card slot (folding rough paper over the end of the card, wetting it with pure alcohol, and feeding in/out repeatedly) then resoldered it. There were quite a few solder connections on the connector that were cold - they bubbled when heated - which had to be desoldered and resoldered.
Game now boots and plays.