The sound recently stopped working on Bally Fathom with the Squawk & Talk model AS2518-61a sound card. It was working fine then went completely silent. I could see the correct number of flashes of the LED when it was installed in the game. However, no sound was heard from the sound card, even after turning the volume control knob up and down.

When I bench test the board using an ATX pc power supply, there are no flashes at all on the LED. This is the type of pc power supply where you have to connect the green wire to the ground to turn on the power. Not sure if that matters. No sound is heard from the attached speaker. Pushing the self test button does nothing either.

Also I measure around 5vdc right after boot up at TP2. Soon after that, it drops down to 1.33vdc.

The board already has new capacitors installed.

Based on the schematic, would it make sense to swap VR1 LM323 ? Or test anything else in that circuit?

I have access to 2 more non-working Squawk & Talk boards also, which have various socketed chips.

Found a cold solder joint on VR1 the 5vdc regulator LM323. Reflowed the solder and voltage staying good at +5vdc now.

Was able to push the test button repeatedly and hear speech through the speaker.

Not sure why the LED does not flash at all on the bench.

Decided to try and fix one of the non working Squawk and Talk boards. This one came from a Mr. & Mrs. Pacman. First, I had to undo the soldered wires on the EE jumpers that I made while troubleshooting Fathom. I double checked the rest of the jumpers on the board with pinwiki and seems to be correct.

Figured out how to get the LED flashing, it depends how the board is connected to power supply. At first I connected +12 volts to TP3, and -5 volts to TP4. The LED does not flash in that setup.

Read another repair guide http://www.pinwiki.com/wiki/index.php?title=Leon_Borre_Bally_-61_Squawk_and_Talk_Sound_Repair
which says "12 volts at J1, pin 17= 12 pin 16 = ground . Make a connection between C14 and C15 both - sides ... -5volts arriving at TP4". The LED does flash when I hook up to power that way. Perhaps it's simply the C14-C15 connected by an alligator clip wire that causes LED flashing, not sure.

At first the LED was flashing 2 times and stopping. According to the guide this means U11 is bad. Started swapping different PIA Chips into U11 but no change. What I noticed was if I wiggled the jumper wire connected to C15, then rebooted the board it did occasionally get 4 flashes. So the logic side of the board was working sometimes! However no sounds were produced out of the speaker when pushing self test button after a successful boot. Decided to leave that same PIA chip in U11 that managed to boot up in place and it's still in there now. I checked all the connections from U11 pia chip with the schematic and buzzed it out with voltmeter in continuity test mode and it all tested good. So the socket for U11 should be good. Also I tested all the chips on the board for 5vdc and they all measure good.

Since the problem seemed to be related to a bad cap (C15), decided to re-cap the entire board with a Great Plains cap kit. My best guess was maybe the 5volts dc is good but there could be not enough current to consistently power all the chips through a full boot?

Now that the board is recapped, I am still mostly getting 2 flashes. Occasionally if I play around and boot it up many times, it will get 4 or 5 flashes. However I thought it's only supposed to flash 4 times? So five flashes seems bad, correct? Usually the only thing that gets it to go past 2 flashes is rebooting by pulling and reconnecting the alligator clip wire hooked up to C15 which causes alot of static on the speaker and a little spark. (probably bad for all the chips). Whenever I get the 4 or 5 flashes, pushing the self test button produces no sounds out of the speaker.

Now, I am stumped what to do next to fix this board. I have access to a scope if needed. What's the next step to get this board fixed?

Managed to get 1 of the 2 spare boards partially working! It reliably boots up, with 5 flashes. The I can push the test button and the board can run through the test mode speech sounds. All of the speech is playing correctly. However no sounds are playing. There's supposed to be a sound at the end of the test and I can hear the sound try to play but the volume is extremely low and barely perceptible.

Followed these instructions to build an arduino test board which can trigger all the sounds that the board will play one by one: http://www.pinballinfo.com/community/threads/controlling-bally-sound-boards.23456/post-135542

After going thru the test, the board can only play the speech sounds but none of the regular sounds are playing.

Let me know if there's something I should check out or fix next on this board to get all the sounds working.

I replaced U13 with a socket and a new LM3900 chip, that did not fix the problem of no regular sounds playing.

However just noticed that if I ran a jumper wire between U13 pin 3 to U13 pin 11, most of the sounds play correctly.

Looking at the schematic, the regular sounds are generated at AY3-8912 sound chip at U12 which feeds into U13 then eventually feeds U14.

Thinking the next step is try changing U14, maybe that chip has gone bad on certain inputs and needs to be replaced?

U14 is atleast partially working, because the voice does play. By jumpering over from pin 3 to pin 11, it looks like the regular sounds are being sent through the working amp on U14. Whereas without the jumper the regular sound goes to a bad amp on U14?

Found a bad potentiometer at R70. Put in a 270 ohm resistor on the back temporarily.

Now finally have all sounds and voices playing with good volume!