Quoted from squad8:
I finally got some time to get back on this. What I found is the game can sit in attract mode with a stable 4.95 volts on U8 pin 40, but when you go into solenoid/sound test it goes to 0.0 volts, and stays there until the game is rebooted.
The above isn't consistent with the below in terms of what the MPU board should be seeing of the gated /BUSY signal. According to the above, MPU U11 pin 18 should be low but showing pulsing. Can you recheck it?
Quoted from squad8:
On the mpu U11 pin 18, during power up it starts low then goes high for a few seconds, and goes back low. It remains low in attract mode, and through solenoid test.
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Not even any change from low to high or high to low on any of the U9 speech ROM pins *after* solenoid test #29
Remove and reinstall the speech processor a couple of times to get it to swipe in the IC socket just in case there's some poor connection there.
If it makes no difference, power off, pull out the speech processor at U8 and leave it out, power on.
Use a small screwdriver to touch pin 11 in the U8 socket - make sure your hand is touching the metal part of the screw driver. Does it produce any hum from the speaker? If it doesn't, find resistor R45 (next to the big blue capacitor) and very briefly place a short circuit across it. Do you get any click/pop from the speaker? We are just checking if the amplifier circuit on the speech board is doing anything.
If the amplifier produces an audible effect, then it might be time to invest in a new speech processor chip.
http://www.gameroomrepair.com/ICparts/ICparts.htm#S14001
BTW, do you have any way of dumping the U9 speech EPROM to verify it's good?