WPC95 Scared Stiff wouldn't boot (no 5 volts at driver board or MPU) and was blowing fuse 105.
I assumed a failed bridge rectifier so I replaced the usual suspects.
D7, D8, D9, D10
Still no 5v at driver board. Fuse 105 no longer blows.
I replaced Q1 (LM317k) voltage regulator. Checked all paths and througholes to the best of my ability.
Powered the game up and get one 'bong' then 5 volts goes out on the driver board.
I replaced Q1 voltage regulator again. Powered up with MPU disconnected. 5v is now present. Voltages at MPU connector are correct.
Connected the MPU at J101 and the ribbon cable. Powered up and again one 'bong' and then lost 5v at the driver board again.
Replaced Q1 (third time) and powered up and I have 5 volts again at the driver. I haven't hooked the MPU up again as I expect the same to happen.
What can I check to prevent another Q1 voltage regulator failure before hooking the MPU up again? The connectors and cables test fine. Could there be an issue or short at the MPU causing Q1 to fail on the driver board? Do I need to power up the MPU on the bench or what would be the next step? Thanks!