: This is the most comprehensive "paper" available. You can view or download the Service Manual for GH-035 Board on the Internet Archive .
A common failure point is the 3.3V standby line. According to the updated schematic, CXD999 (the main I/O controller) won’t release the reset line to the UPD until the 3.3V is stable. If your UPD is warm but the system is dead, probe pin 12 – it should go high within 200ms of adapter insertion. ps2 slim schematic diagram upd