(Topic ID: 268771)

Flash Gordon has Talks but no Squawks


By Fytr

13 days ago



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  • Latest reply 5 days ago by Quench
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S&T_Snd_Signals_Knocker.png
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SAndTJ1Schematic (resized).JPG

#1 13 days ago

So Flash Gordon I'm working on has speech but no sound. Caps are fresh, and I've replaced the pots.

The J1 connector and wires were heavily hacked and at one point I was able to get game sounds working by wiggling the wires connected to J1 a bit, but never for long - usually just had static.

By "game sounds", I mean the ones triggered by in game switches and flashers. If I press the self-test button on the Squawk an Talk board all the speech works and also the sound effect at the end of the test, though I believe that sound is MPU generated and not part of the sound circuit that isn't working as noted below:

Source: http://www.pinrepair.com/bally/squawk.htm
"S&T Sound Generation.
Sound generation/special audio effects are handled in two ways: 1 - A General Instruments AY3-8912 PSG IC fitted in U12 under control of the PIA at U11 (which is in turn controlled by the S+T 680x) generates basic square wave tones, noise and sound shaping envelopes that control the output
amplitude to the amplifier circuits. These tones are limited in scope (how many different square waves can you have?). "

So I replaced the J1 connector and cleaned up the wires. Now I get nothing at all in terms of sound. On startup there is a clicking sound like someone tapping on a microphone. Though the self-test work fine still.

I swapped in a known working U11 PIA chip and no difference. I don't have a spare U12 though so will need to order one if I don't find another issue.

I've been testing the connections between J1 pins and their various landing pins on other boards to verify my connector wiring, and I've run into a few that are referenced in the schematic that I can't figure out where they are (shown with "?" next to them in the pic below).

SAndTJ1Schematic (resized).JPG

J1 P9 -> A3J3-5 ?
J1 P10 -> A3J3-12 ?
J1 P15 -> A3J3-23 and A2J3-19 ? (I discovered that A2J4-2 has continuity with J1 P15 though)

Does anyone know where these reside? I'd just like to know 100% that the connector is solid before I go and order a new U12 (AY3-8912 PSG IC). Other suggestions are also welcomed.

#2 13 days ago

Have you already tried adjusting the sound setting?

Self test option #18, press start button until 03 is shown on display.

#3 12 days ago
Quoted from Fytr:

J1 P9 -> A3J3-5 ?
J1 P10 -> A3J3-12 ?
J1 P15 -> A3J3-23 and A2J3-19 ? (I discovered that A2J4-2 has continuity with J1 P15 though)

A3 refers to the solenoid driver board.
So A3J3-5 is solenoid driver board, connector J3 pin 5.

A3J3-5 is 43 volts and may be wired for backward compatibility to the first gen Bally sound board. The S&T does NOT use it.
A3J3-12 is the unreg 12 volts - required by the S&T board to power the output amplifier and LED.
A3J3-23 is ground. Required.
A2J3-19 is a mistake on that wiring diagram - it's referring to the earlier Bally rectifier board that was in the head. It should be A2J4-2

Do you have the five "EE" jumpers below the AY-3-8912 removed to enable the AY-3-8912 sound generator?
You've definitely replaced capacitor C36?

Are you getting any activity on test point TP7 when the S&T board should be playing sound effects?

#4 12 days ago
Quoted from EEE:

Have you already tried adjusting the sound setting?
Self test option #18, press start button until 03 is shown on display.

Good thinking, yes #18 is on 03.

Quoted from Quench:

A3 refers to the solenoid driver board.
So A3J3-5 is solenoid driver board, connector J3 pin 5.
A3J3-5 is 43 volts and may be wired for backward compatibility to the first gen Bally sound board. The S&T does NOT use it.

Okay, there is no continuity between them, which is fine then.

Quoted from Quench:

A3J3-12 is the unreg 12 volts - required by the S&T board to power the output amplifier and LED.
A3J3-23 is ground. Required.
A2J3-19 is a mistake on that wiring diagram - it's referring to the earlier Bally rectifier board that was in the head. It should be A2J4-2

All checkout.

Quoted from Quench:

Do you have the five "EE" jumpers below the AY-3-8912 removed to enable the AY-3-8912 sound generator?
You've definitely replaced capacitor C36?

Confirmed jumpers below U12 are not there, no continuity between the points either.
I didn't replace C36 myself but it is a modern looking cap.

Quoted from Quench:

Are you getting any activity on test point TP7 when the S&T board should be playing sound effects

I'm not precisely sure what you mean by "activity", but TP7 reads 5.09 -> 5.10 VDC, seems to waver between those two values but couldn't say that it's in response to a sound being played or not.

#5 12 days ago

Try the sound test using the red button inside the coin door. I think you press it four times to get to the sound test.

#6 12 days ago
Quoted from Fytr:

I'm not precisely sure what you mean by "activity", but TP7 reads 5.09 -> 5.10 VDC, seems to waver between those two values but couldn't say that it's in response to a sound being played or not.

If TP7 is sitting at 5 volts that's no activity, i.e. the signal is not changing.

With book-keeping #18 set to 03, the game will play background sound effects in game, or just put the game in sound test mode from the coin door switch like jj44114 said. Then remeasure TP7. I don't have a game setup but I'm guessing it should be around 2.5 volts when the AY-3-8912 is playing audio since it's only outputting square waves.

BTW, you are getting 5 LED flashes on the S&T?

#7 9 days ago
Quoted from Quench:

If TP7 is sitting at 5 volts that's no activity, i.e. the signal is not changing.
With book-keeping #18 set to 03, the game will play background sound effects in game, or just put the game in sound test mode from the coin door switch like jj44114 said. Then remeasure TP7. I don't have a game setup but I'm guessing it should be around 2.5 volts when the AY-3-8912 is playing audio since it's only outputting square waves.
BTW, you are getting 5 LED flashes on the S&T?

Yes, 5 flashes on boot on the S&T board.

Okay, I messed up earlier, was checking TP2, not TP7.

Using TP7 with the sound test (4th press on the service button on the coin door) I see no voltage change, steady at 0.044VDC. However, if I press the self-test button on the S&T board I do see the voltage changing on TP7 while the speach is playing, and even more dramatically during the sound effect at the end of the test.

#8 9 days ago
Quoted from Fytr:

and even more dramatically during the sound effect at the end of the test.

Is this immediately after the last word is spoken? - and at this point you don't hear anything right? This is when the sound board self test plays an effect through the AY-3-8912.

What does TP7 do in game mode? (when the sound board is playing background sounds), and when you hit some switches? Sound test via the coin door just produces a filtered noise effect - they should have used a sound effect with tones and more substance.

Can you post a clear high res picture of the sound board?

Do you have an oscilloscope by any chance?

#9 9 days ago
Quoted from Quench:

Is this immediately after the last word is spoken? - and at this point you don't hear anything right? This is when the sound board self test plays an effect through the AY-3-8912.

So retested with the multimeter, self-test on the board TP7 ranges between 0.06 and 0.071VDC while the speech is playing, until the final sound effect plays (which I *can* hear), then the VDC jumps around to 0.2VDC TP7 while it plays.

What does TP7 do in game mode? (when the sound board is playing background sounds), and when you hit some switches? Sound test via the coin door just produces a filtered noise effect - they should have used a sound effect with tones and more substance.

Nada, TP7 sits at 0.066VDC during gameplay, including when targets are pressed. Same with self-test from coin door button pressed 4 times.

Can you post a clear high res picture of the sound board?

IMG_7837 (resized).JPG

Do you have an oscilloscope by any chance?

No scope. I do have a logic probe though.

#10 9 days ago
Quoted from Fytr:

until the final sound effect plays (which I *can* hear)

Ah ok, so if you get the synthesized sound effect directly after the last speech "15 seconds" is spoken in the S&T self test, then the AY-3-8912 is producing sound.

Are you getting speech during gameplay? - i.e. when you start a new game does it say "Flash, Emperor Ming awaits"

#11 9 days ago

Wouldn't the AY-3-8912 output test pad output be an AC measured signal? Lowest AC voltage range. Probably under 1vac

Could check the LM3900 output at U13 at P4. If that is bad would probably silence or reduce the volume of the ay-3-8912 below audible level.

If you find the AY-3-8912 chip has no output but it passes the power on self test, it is still probably bad despite the power on self test. I know they can fail in the way where just nothing comes out of them yet the CPU thinks it can control it OK so the power on self test passes.

#12 9 days ago
Quoted from Quench:

Are you getting speech during gameplay? - i.e. when you start a new game does it say "Flash, Emperor Ming awaits"

Okay, something strange just happened, fired up the game and heard a siren sound during bootup (never played any sound during boot before). Started a game, sound playing! Not sure it's the right sounds though, if I hit targets different sounds play, but sometimes I get speech that repeats quickly, like "15, fif, fift, fifteen seconds".

Second boot, no startup sound. Start game, no speech at beginning. Hit targets maybe one in 4 or 5 switch hits will play a sound, doesn't seem to be same sound each time either.

Using the cabinet door sound test I heard the square wave sound for about 4 loops then it quits.

Third boot, no sound at startup or during game except it plays that square wave test sound maybe once in 10 or 15 switch hits. Self test via coin door plays nothing.

Self-test via S&B switch works fine still.

So it's very intermittent. Assuming the connector is fine now, maybe a socket issue?

#13 9 days ago

And do the sounds/speech come back when you wiggle the 15 pin harness connector on the sound board as per your first post? i.e. are you sure this isn't just a connector issue?

#14 8 days ago
Quoted from Quench:

And do the sounds/speech come back when you wiggle the 15 pin harness connector on the sound board as per your first post? i.e. are you sure this isn't just a connector issue?

Wiggling the harness doesn't seem to affect anything.

So now when I boot the game I get a startup sound, though not always the same one. When I start a game no sound or speech at all. If I hit targets/close switches the only ones that reliably play a sound are the bottom pop bumpers. They typically play the square wave test sound when hit and it will keep playing until I hit another switch, which will end the sound. Once in awhile a laser sound will play when the pop bumper is hit instead, but rarely.

#15 8 days ago

Pull the logic probe out and hook it up.

Put the game in solenoid test mode (yes you read right, solenoid test mode not sound test).

Without touching the J1 connector, probe the following pins on the U16 chip on the S&T board:

Does the logic probe indicate any changes on the following pins throughout the full solenoid test sequence or do any of them just stay on the same logic level throughout the test?

U16 pin 13 14
U16 pin 11
U16 pin 9
U16 pin 7
U16 pin 5
U16 pin 3

U16 pin 14 15
U16 pin 12
U16 pin 10
U16 pin 6
U16 pin 4
U16 pin 2

Then go to sound test mode and recheck just the following two pins:

U16 pin 3
U16 pin 2

#16 7 days ago

Results:

U16 pin 13: Nothing (neither high nor low lit on logic probe)
U16 pin 11: High then short pulse to low as some/most coils fire, but not all.
U16 pin 9: High then short pulse to low as some/most coils fire, but not all.
U16 pin 7: High then short pulse to low as some/most coils fire, but not all.
U16 pin 5: Nothing (neither high nor low lit on logic probe)
U16 pin 3: Low
U16 pin 14: High with short pulse to low on some coils.
U16 pin 12: Nothing lit with short High pulse on some coils.
U16 pin 10: High
U16 pin 6: High
U16 pin 4: Nothing
U16 pin 2: High

Then go to sound test mode and recheck just the following two pins:
U16 pin 3: High with short pulse to low every second or so.
U16 pin 2: High with short pulse to low every second or so.

Note that if I just leave the sound test on I'm not hearing anything but every few mins it might play a sound for a couple of seconds and then stops again. When it does play, it seems to play for the full sound/1 second, and then when it quits there is a quiet "pop" sound instead of the next sound being played.

#17 7 days ago

U16 is an "inverter" chip with 6 inverters, what comes out of each inverter is the opposite logic level of what goes in and you aren't getting consistent results to this rule.

The first lot of 6 pins I listed above are individual U16 inputs, the second lot of 6 pins are the respective U16 outputs (actually not quite, see below)

So where input pin 3 is low and its respective output pin 2 is high, it's correct.

Where input pin 5 is nothing and its respective output pin 4 is nothing, this is actually incorrect. The output must always be either high or low.

Where input pin 7 is high pulsing low and its respective output pin 6 is high, is bad. Pin 6 should be low pulsing high.

Where input pin 9 is high pulsing low and its respective output pin 10 is high, is bad. Pin 10 should be low pulsing high.

Where input pin 11 is high pulsing low and its respective output pin 12 is nothing is bad. Pin 12 should be low pulsing high.

Where pin 13 is nothing and output pin 14 is high pulsing low is a ... mistake on the S&T schematic, sorry it's really pin 14 as the input and pin 15 is its output.

First of all, just make sure U16 is getting proper 5 volts power. Pin 8 is the ground pin and pin 1 is 5 volts power in.
Also, change the logic probe to "CMOS" mode and redo the solenoid test, but just check the output pins only (the second lot of 6 pins I listed above - I've amended the incorrect pin numbers).

#18 7 days ago

I would go over the input connector again. Looks like the IDC plug was replaced and the wire punched down in a new spot. Some of these original punched down places may have frayed wires contributing to intermittent continuity problems. Quench's test would isolate the problem to certain wire if find one of the sound/solenoid select bits is missing.

Untitled (resized).png

#19 7 days ago
Quoted from Quench:

U16 is an "inverter" chip with 6 inverters, what comes out of each inverter is the opposite logic level of what goes in and you aren't getting consistent results to this rule.
The first lot of 6 pins I listed above are individual U16 inputs, the second lot of 6 pins are the respective U16 outputs (actually not quite, see below)
So where input pin 3 is low and its respective output pin 2 is high, it's correct.
Where input pin 5 is nothing and its respective output pin 4 is nothing, this is actually incorrect. The output must always be either high or low.
Where input pin 7 is high pulsing low and its respective output pin 6 is high, is bad. Pin 6 should be low pulsing high.
Where input pin 9 is high pulsing low and its respective output pin 10 is high, is bad. Pin 10 should be low pulsing high.
Where input pin 11 is high pulsing low and its respective output pin 12 is nothing is bad. Pin 12 should be low pulsing high.
Where pin 13 is nothing and output pin 14 is high pulsing low is a ... mistake on the S&T schematic, sorry it's really pin 14 as the input and pin 15 is its output.
First of all, just make sure U16 is getting proper 5 volts power. Pin 8 is the ground pin and pin 1 is 5 volts power in.
Also, change the logic probe to "CMOS" mode and redo the solenoid test, but just check the output pins only (the second lot of 6 pins I listed above - I've amended the incorrect pin numbers).

Results:

4.99VDC steady on u16 p1.

Using CMOS mode makes a difference:

U16 pin 14: High to low
U16 pin 12: Low to high
U16 pin 10: High to low
U16 pin 6: Low to high
U16 pin 4: Low
U16 pin 2: High

#20 7 days ago

So a complete comparison of U16 input pins to output shows:

p9: HtL -> p10: LtH
p7: HtL -> p6: LtH
p11: HtL -> p12: LtH
p14: LtH -> p15: HtL
p3: Low -> p2: High
p5: High -> p4: Low

So everything checks out. ?

#21 7 days ago
Quoted from Fytr:

So a complete comparison of U16 input pins to output shows:
p9: HtL -> p10: LtH
p7: HtL -> p6: LtH
p11: HtL -> p12: LtH
p14: LtH -> p15: HtL
p3: Low -> p2: High
p5: High -> p4: Low
So everything checks out. ?

Well dang, saw some inconsistencies between my two captures above so went and did another pass with CMOS=on.

These set is mismatched now...

p5: Nothing -> p4: Low (with some noise)

If I touch the probe on P5, no lights, then if I touch on P4 afterwards, it starts with flickering High then gradually fades to solid low over about 1-2 seconds. Strange.

It looks like U16 is a CMOS 4049 hex inverter, I just happen to have some replacements on hand.

Should I go ahead and swap it out, or is this possibly still wiring related?

#22 7 days ago

connecters X 3...………………...

#23 7 days ago
Quoted from Fytr:

Well dang, saw some inconsistencies between my two captures above so went and did another pass with CMOS=on.
These set is mismatched now...
p5: Nothing -> p4: Low (with some noise)
If I touch the probe on P5, no lights, then if I touch on P4 afterwards, it starts with flickering High then gradually fades to solid low over about 1-2 seconds. Strange.
It looks like U16 is a CMOS 4049 hex inverter, I just happen to have some replacements on hand.
Should I go ahead and swap it out, or is this possibly still wiring related?

With the MM P4 reads 5.0vdc, P5 =0.00vdc.
For comparison, p3: Low (0.18vdc) -> p2: High (2.4vdc)

So to me that means that P4 (input) is high, and P5 (output) is low, which is correct. For some reason my probe doesn't like 0.0vdc.

In any case, all input and outputs pan out, right?

#24 7 days ago
Quoted from barakandl:

I would go over the input connector again. Looks like the IDC plug was replaced and the wire punched down in a new spot. Some of these original punched down places may have frayed wires contributing to intermittent continuity problems. Quench's test would isolate the problem to certain wire if find one of the sound/solenoid select bits is missing.
[quoted image]

Well I've tested all the J1 connector wires for continuity with success in every case. Suggestions on how to proceed?

#25 7 days ago

Cluster fuck. send me the board, I'll fix it. You pay shipping.

#26 7 days ago
Quoted from Fytr:

p14: LtH -> p15: HtL

Have you got these two pins mixed up by any chance? The results should be the other way around.

Quoted from Fytr:

p5: Nothing -> p4: Low (with some noise)

You can ignore pin 5 of U16, actually nothing is connected to it so that inverter isn't used - was wired for future expansion.

Quoted from Fytr:

Well I've tested all the J1 connector wires for continuity with success in every case.

Did you test from wires at the connector to the first component on the S&T board or just connector back to MPU board connector? In other words is the board seeing continuity to the wires at the connector?

Quoted from Fytr:

For comparison, p3: Low (0.18vdc) -> p2: High (2.4vdc)

What was the game doing when you measured this? 2.4V out is very low for a "high" state signal on a CMOS chip. If the levels on these pins were steady (i.e. not actively pulsing) then this is suspect.. A high logic level out on a CMOS chip (which this is) should be 2/3 and above of supply voltage i.e. 3.3V or higher.

BTW, you might want to pull out the AY-3-8912 and give the pins a gentle clean with a small brass wire brush. Its pins look rather tarnished. The sound command sent from the MPU board through the U16 inverter goes to input pins on the AY-3-8912 - maybe you've got a bad connection there.

#27 7 days ago
Quoted from Quench:

Have you got these two pins mixed up by any chance? The results should be the other way around.

Dang. Yes I did, retesting shows p14: HtL -> p15: LtH

You can ignore pin 5 of U16, actually nothing is connected to it so that inverter isn't used - was wired for future expansion.

Okay, good to know.

Did you test from wires at the connector to the first component on the S&T board or just connector back to MPU board connector? In other words is the board seeing continuity to the wires at the connector?

I tested from the connector to connector, not connector to S&T board. So the J1 connector from S&T shows continuity with the expected various other connectors at the other ends of the wires.

I'll review the schematics and see if I can figure out where to test the J1 connector on the S&T board as well.

What was the game doing when you measured this? 2.4V out is very low for a "high" state signal on a CMOS chip. If the levels on these pins were steady (i.e. not actively pulsing) then this is suspect.. A high logic level out on a CMOS chip (which this is) should be 2/3 and above of supply voltage i.e. 3.3V or higher.

Retested:

With solenoid test running: P2: 5.4 vdc steady, P3: 0.133 vdc.
With sound test running: P2: 0.38 vdc, P3: 4.15 vdc

BTW, you might want to pull out the AY-3-8912 and give the pins a gentle clean with a small brass wire brush. Its pins look rather tarnished. The sound command sent from the MPU board through the U16 inverter goes to input pins on the AY-3-8912 - maybe you've got a bad connection there.

Yeah, I noticed that earlier and have already cleaned the bottoms of those pins. They weren't nearly as bad as the exposed tops though.

#28 6 days ago
Quoted from Fytr:

With solenoid test running: P2: 5.4 vdc steady, P3: 0.133 vdc.
With sound test running: P2: 0.38 vdc, P3: 4.15 vdc

That output voltage on pin 3 looks much better.

It appears your U16 is working.
Since the U16 outputs go to AY-3-8912 inputs, might be worth probing those input pins on U12 during solenoid test to confirm no issues with tarnished pins/U12 socket:
U16 pin 14 --> U12 pin 14
U16 pin 12 --> U12 pin 13
U16 pin 10 --> U12 pin 12
U16 pin 6 --> U12 pin 11

There's a special protocol for the MPU board sending a sound command to the S&T board. The protocol is timing related by the MPU boards CPU.
We recently had someone running an aftermarket MPU board that was configured for Sterns MPU-200 CPU speed which caused problems with the S&T playing correct speech/sounds. Are you running a factory Bally MPU board or aftermarket? Do you have anything that can measure the MPU boards CPU frequency, i.e. a frequency counter? maybe your multi-meter has a Hz (frequency) feature?

#29 6 days ago
Quoted from Quench:

That output voltage on pin 3 looks much better.
It appears your U16 is working.
Since the U16 outputs go to AY-3-8912 inputs, might be worth probing those input pins on U12 during solenoid test to confirm no issues with tarnished pins/U12 socket:
U16 pin 14 --> U12 pin 14
U16 pin 12 --> U12 pin 13
U16 pin 10 --> U12 pin 12
U16 pin 6 --> U12 pin 11

Okay, so I realized that my manual doesn't include schematics for the S&T board. The pins on the J1 connector looked a little tired so I went ahead and repinned it. Then with the plug installed I tested for continuity from the back of the plug "socket" to a test point on the board and all checks out. No change at all to the sound behavior after this though.

U16 pin 14 HtL --> U12 pin 14 LtH (reversed)
U16 pin 12 LtH --> U12 pin 13 LtH
U16 pin 10 L --> U12 pin 12 L
U16 pin 6 HtL --> U12 pin 11 LtH (reversed)

There's a special protocol for the MPU board sending a sound command to the S&T board. The protocol is timing related by the MPU boards CPU.
We recently had someone running an aftermarket MPU board that was configured for Sterns MPU-200 CPU speed which caused problems with the S&T playing correct speech/sounds. Are you running a factory Bally MPU board or aftermarket? Do you have anything that can measure the MPU boards CPU frequency, i.e. a frequency counter? maybe your multi-meter has a Hz (frequency) feature?

Based on the behavior where it seems like once the sound chip receives a command to play a sound, it does so until finished, and the fact that the sounds will play when one switch is closed and stop when another is closed, this seems more like a signalling issue between the MPU and the sound chip (as you've indicated, above).

MPU board is a Bally AS-2518-35 that came from a donor and I re-jumpered for new ROMs.

I'd don't have a way to read frequencies, unfortunately.

Any idea where I could find the schematics for the S&T board?

#30 6 days ago
Quoted from Fytr:

Any idea where I could find the schematics for the S&T board?

The Fathom schematic has a legible S&T scan.

Gotta run, I'll come back later and comment.

#31 5 days ago
Quoted from Fytr:

and the fact that the sounds will play when one switch is closed and stop when another is closed

Sorry, I'm confused. I thought you weren't getting any game sounds. Are you saying you're getting some sound effects but not others in game play? If yes we at least know the sound effect mixer/amplifier circuits after the AY-3-8912 are working.

Quoted from Fytr:

U16 pin 14 HtL --> U12 pin 14 LtH (reversed)
U16 pin 12 LtH --> U12 pin 13 LtH
U16 pin 10 L --> U12 pin 12 L
U16 pin 6 HtL --> U12 pin 11 LtH (reversed)

I think you might have mixed up some of those pins again. Note, your U16 pin 10 being low indicates you may have lost continuity to the input side (pin 9) of that inverter that comes from pin 3 of the connector - i.e. a bad connection at pin 3 of the sound board connector.

Sorry if the following is information overload but I'm trying to arm you with the behavior of these sound select signals.

There are four signals at the MPU board J4 connector called "momentary solenoid / sound data". These are MPU J4 pins 4 to 1.
These four signals are used in a binary fashion to select a momentary solenoid to activate or a sound/speech to play. These signals will sit at a logic high level when idle and certain combinations will pulse low depending on which solenoid/sound to activate/play.

MPU J4 pin 10 is the solenoid/sound control select signal.
When it's high, activity on the "momentary solenoid / sound data" signals will be accepted by the sound board, and ignored by the solenoid driver board.
When it's low, activity on the "momentary solenoid / sound data" signals will be accepted by the solenoid driver board, and ignored by the sound board.

Because the "momentary solenoid / sound data" signals are shared between the two boards, running solenoid test mode guarantees activity on all four of those signals because many different solenoids are being activated, whereas sound test mode is only activating one sound so it's possible some of those four signals might not change state. If you've wondered, that's the reason we've been running these tests in solenoid test mode.

Looking at the solenoid driver board schematic, when the knocker coil activates, the following will happen along the signal chains:

- "momentary solenoid / sound data" signal PB3
MPU U11 pin 13 pulses from HtL, --> MPU J4 pin 1 --> Sound board J1 pin 4 --> Sound board U16 pin 7 --> Sound board U16 pin 6 pulses LtH --> Sound board U12 pin 11 pulses LtH

- "momentary solenoid / sound data" signal PB2
Stays high, no change in signal state

- "momentary solenoid / sound data" signal PB1
MPU U11 pin 11 pulses from HtL, --> MPU J4 pin 3 --> Sound board J1 pin 2 --> Sound board U16 pin 11 --> Sound board U16 pin 12 pulses LtH --> Sound board U12 pin 13 pulses LtH

- "momentary solenoid / sound data" signal PB0
Stays high, no change in signal state
.
Follow the signal colors from MPU board U11 to S&T board U12
.
MPU_Sol-Snd_Signals_Knocker.png
S&T_Snd_Signals_Knocker.png

.
When the right thumper bumper activates, the following will happen:

- "momentary solenoid / sound data" signal PB3
Stays high, no change in signal state

- "momentary solenoid / sound data" signal PB2
MPU U11 pin 12 pulses from HtL, --> MPU J4 pin 2 --> Sound board J1 pin 3 --> Sound board U16 pin 9 --> Sound board U16 pin 10 pulses LtH --> Sound board U12 pin 12 pulses LtH

- "momentary solenoid / sound data" signal PB1
Stays high, no change in signal state

- "momentary solenoid / sound data" signal PB0
MPU U11 pin 10 pulses from HtL, --> MPU J4 pin 4 --> Sound board J1 pin 1 --> Sound board U16 pin 13 --> Sound board U16 pin 14 pulses LtH --> Sound board U12 pin 14 pulses LtH
.
Follow the signal colors from MPU board U11 to S&T board U12
.
MPU_Sol-Snd_Signals_RightPopBumper.png
S&T_Snd_Signals_RightPopBumper.png

Start by probing the U12 pins in these tests - if any are stuck low, work your way back up the chain to the source of the signal to find out where you're getting a loss of pulse activity.

If the behavior on those signals is happening correctly, then you are left with two things.
U11 on the sound board controls the communications direction of the U12 AY-3-8912 sound chip. You've already changed U11 so that leaves U12 as a suspect.
As mentioned previously there is a special protocol from the MPU board to the sound board that is timing related to the MPU board. If you have another Bally MPU board, try swapping it in.

#32 5 days ago

Wow, this is fantastic!

After looking through the S&T schematic yesterday I could see the 4 sound select lines you are referencing and how I should be able to trace them back. This explanation makes that a whole lot easier for me. I really appreciate this, I know how much time it can take to put together in-depth responses.

Quoted from Quench:

Sorry, I'm confused. I thought you weren't getting any game sounds. Are you saying you're getting some sound effects but not others in game play? If yes we at least know the sound effect mixer/amplifier circuits after the AY-3-8912 are working.

At one point during my testing last week the game was playing sound intermittently (which I noted). To summarize:

- On startup it sometimes played a sound, though not always the same sound.
- If I left the sound test running every few mins it might play a sound for a couple of seconds and then stop again. When it does play, it seems to play for the full sound/1 second, and then when it quits there is a quiet "pop" sound instead of the next sound being played.
- Starting a game, no sound. Closing switches would sometimes play a sound, again, not always the same sound for the same switch. Lower PF pop bumpers seemed reliable to trigger a sound, sound would keep playing until I closed another switch, then it would stop (and not play the sound for the switch).

All of this was sporadic and I haven't gotten any sounds this way in the last day or two. On-board self-test still works fine.

It does seem to be that there is no problem downstream of the sound chip, it is in determining what sound to play, and when. Once a sound is initiated, it plays and sounds fine.

Quoted from Quench:

I think you might have mixed up some of those pins again. Note, your U16 pin 10 being low indicates you may have lost continuity to the input side (pin 9) of that inverter that comes from pin 3 of the connector - i.e. a bad connection at pin 3 of the sound board connector.

I will retest in a bit and do some further tracing and report back.

Thanks again!

#33 5 days ago

Okay, I have exciting news!

With all of my apparent mixups when testing and reporting values on U16 I was becoming suspicious. I'm not perfect but I'm not *that* error prone.

So I retested U16 P10 and P12 and indeed P10 was low and not changing, though P9 was.

Decided that U16 had to be flaky and reporting different results at different times during my testing - replaced U16 and the game is working perfectly now!

I would like to extend my heartfelt appreciation for all the help provided.

#34 5 days ago
Quoted from Fytr:

replaced U16 and the game is working perfectly now!

Phew, I was getting worried this was going to be some weird issue!

Great to hear it's working!

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