Hello! I have a system 11 game (high speed) that is not booting at all in the game. The CPU gets 5v to the power plug, but when I plug it into the board, it drops to 0.5V. So, I know we have a short on the board.

Ive taken it out, and plugged it into a nice adjustable power supply. Oddly enough, it boots fine. The power supply send exactly 5V to the board, but all points tested on the board are only 4.4V. I imagine that my adjustable power supply is able to supply more current to keep the board booted, while the pinball power supply does not.

So....I inserted the Leons System 11 test ROM. It all tests perfectly....but one unusual portion...the 1J21ribbon connector header to the sound board. Pins 1-5 test correctly, but Pins 6-10 are not strobing. According to the manual, this is only connected to 2 things...The U42 PIA and the package resistor SRC1.

Here is the catch...the U42 is testing / strobing fine on all outputs. So, Im not sure how this would be the issue. On the package resistor, all pins test at 4.8k except for pin 8. Its coming in at 2.5K.

Any ideas what may be causing pins 6-10 on the sound connector to not strobe if the U42 pins are strobing? Thanks for any ideas!

I think I made a mistake on the pinout. I believe the count is not down the long end of header, but side by side. I’ll check when I get back home.

I guess the next question would be: is it normal to see a 0.6v drop from the power supply to the board? Seems to be running fine!