Portland, OR
New to me game. This is a strange one. The sound and speech are perfect from the start of the game up until the bonus collect at the end of ball one, then the sound goes silent until the first switch closure of ball 2. This pattern repeats for the rest of the game.
Here's a video of it:
And here's what I've done so far to troubleshoot:
-Confirmed all voltages are present on the sound board.
-Confirmed all 5 sounds are present during solenoid test.
-Confirmed sound board self-test is good.
-Ran the Leon test ROM on the sound board and confirmed PIA outputs and memory is good.
-Verified contents of the sound ROM.
-Burned a new sound ROM for the heck of it and replaced the socketed CPU, PIA, and 6810 with known good chips.
-Disconneted the speech board (and jumpered W1) to remove it from the equation.
-Swapped in a different driver board to make sure it wasn't something in the solenoid drive circuit.
-Monitored the in the inputs of the PIA during bonus collect and cofirmed pins 11, 12, and 14 are all pulsing for the full duration of the collect. PIA outputs that feed the 1408 DAC are dead during this time.
I noticed that pin 13 of IC 6 (output of the 8-input NAND gate) stays high during bonus collect. Pin 13 feeds CB1 of the PIA, but I'm not sure how this line is implemented here. Seems strange to me that the output is locked high while the inputs are just pulsing.
This is starting to exceed my knowledge of this particular board. Hoping that some fresh eyes and smarter heads might be able to see something I'm not. Thanks in advance!
