(Topic ID: 247396)

Black Hole no sound


By CanadianGamer

35 days ago



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#1 35 days ago

I've looked everywhere and can't seem to find an answer to why my Black Hole sound isn't working. I've had the game for a while now and finally have the game playing after installing a new Pascal Janin all in one board. The guy who had the game before me said the sound was working for him, but it never did for me. Maybe he meant "it worked a while ago".

I've re-capped the sound/speech board, and the sound board's power supply. I have 30volts at pin 10, and I get humming from the speakers when I adjust the volume pot but nothing happens when I hit the test button. I've tried grounding pins 2, 8, 9, 11, 12 on the sound board and still no sound, but I do get some light static as the sound attempts to play for a few seconds. I've re-seated all the socketed IC's and they seem to grab on nice and tight. My connectors look like they're in good shape with no burning or corrosion, and they grab the boards very tightly.

I'm not sure what to do next, and I hope someone can steer me in the right direction. Thanks!

#2 35 days ago

you need 4 different powers for sound board power supply . easy mod on pinwiki

5.5.5.5 Sound/Speech Power Supply Board LED's
The Sound/Speech power supply board will get a total of four LED's! These are to indicate the presence of -12 volts, +12 volts, and +30 volts going out to the actual sound/speech board and also to indicate +24 volts coming in to the power supply board.
200px-SSPSLEDlitup (resized).jpg

#3 35 days ago

Ok thanks! I checked the sound board and it has 12v and -12volt, 30 volt, 5 volt.
The sound power supply has 12v, -12v, 5v, but the 24v was up at 30-32volts. I checked my all in one board and the 24 volt for solenoids is high too, so what is doing that? A capacitor by the transformers? I did a bunch of work down there but it was a while ago so I’ll have to dig into it again.
Would the 24volt line being high cause the sound not to work, or worse yet fry something?
Edit: I checked for 24volts at the bridge rectifier, and I know it was 27volts when I checked last time, but now it’s 32volts.

#4 35 days ago
Quoted from CanadianGamer:

The sound power supply has 12v, -12v, 5v, but the 24v was up at 30-32volts.

You mean pin 6 on the sound power-supply board connector is measuring 30 volts? It might be because diode CR3 on that board is shorted.
Disconnect the sound power-supply board and re-measure the voltage on that pin in the connector.

Capacitor C3 on the sound power-supply board filters and raises the DC voltage to over 30 volts. Diode CR3 blocks it from raising the 24V source upstream on the rest of the game.

#5 35 days ago

Thanks Quench. I took the connector off and pin 6 is 32 volts, which connects to cr3 and I get 32v there too. If cr3 is shorted then is that why my pascal all in one board has 32v where it should be 24?
Is it possibly my big transformer that’s going bad?
I have replaced both caps on the sound power supply. Still ultimately trying to get sound going too. Thanks!

#6 34 days ago
Quoted from CanadianGamer:

I took the connector off and pin 6 is 32 volts, which connects to cr3 and I get 32v there too.

You're taking the connector off the sound power-suppy board so that board is disconnected? And then measuring the voltage inside pin 6 of the wire connector and you're still getting 32 volts? I don't have my game handy to check, but it should drop down to around 24 volts according to the schematics. Unless the Pascal board has a capacitor on that supply rail?? I don't know.

With the machine off and using your multi-meter in diode test mode, does diode CR3 on the sound power-supply board checkout ok?

#7 34 days ago

Yes, I tested with sound board power supply with connector off, pin 6 of connector reading 32volts. The diode cr3 checks out ok as well. I didn’t remove it from the board but it gets .600 one way and null the other. That 32 volts starts at the bridge rectifier and is constant through the boards where it should be 24volts. The pascal board has test points and led’s everywhere which is handy, and it’s showing 32volts going to solenoids.

#8 34 days ago

have you checked the speaker , you can use 9v battery and make contact with the leads of the speaker . if good you'll hear scratching sound . if not re-pin pins related to sound , then that's eliminated . check volume control inside coin door . it could be simple

#9 34 days ago

Yes, I can change the volume of the hum and scratch coming from the speakers with the volume pot so both I believe are working. When I ground pin 8 etc on the sound board I can hear a little scratchiness as it tries to play the test sound for a few seconds.

#10 34 days ago

would be nice if you could try sound board in different machine . A3J6 sends the signal to the sound board i would check those connectors .Are the dip switches in the right position .Remove chip from sound board , clean and inspect for broken legs (make sure to install the wright way ) . i have a friend that installed his new roms the wrong way in his sound board it still didn't work and he had to order new ones .Here is a pic of my chip on my 8BD mpu and my sound board was the same . Most chip in sockets where damage . sometimes cleaning and re-seating chip works ( if legs aren't broken ) .
20190716_171139 (resized).jpg

#11 33 days ago

Thanks steamfitter. Yes the dip switches are set correctly, and yes it's too bad I don't have another machine to test it on. There's just an old Bally Future Spa here at the moment. I have had the chips out but they looked good and I didn't clean them. Can't hurt though, so I'll do that after I check connector A3J6.
Thanks for all your help, I really hope to have sound going again. You can't play the game without sound... no point.

#12 33 days ago

I removed all the chips and they look like new. Seems like if I cleaned them I would only chance breaking a pin so I put them back in. The sockets grab them very tightly as well so it all seems good. I know the previous owner said sound was working, but there were numerous problems with it that I've already worked on to get it this far. The small transformer was melted, so I managed to find one of those and replace it. The capacitors are new down there too, and 4 new bridge rectifiers. The guy had a real mess going on, but I have it back to original now according to schematics. Then the new all in one control board came in and took care of any power supply and driver board issues as well. I mounted some pullup resistors on the under playfield transistors and at least now the game will play.

The list of stuff I've done to this thing is extensive, beyond what I've listed, but it will all be for nothing if I don't get the sound working. I'm very hesitant to seek out a new sound board, because I don't even know if it's the problem and they're expensive. Thanks again for all the input.

#13 33 days ago

Just in case, you are aware there’s dip switches not only on the mpu, but also on the sound board, right?

#14 33 days ago

Yes thanks I am aware. The dips on sound board are 1,2,7,8 are off, rest are on.
The all in one mpu has software controlled dips, and they’re all set properly to the speech/sound settings.

#15 32 days ago

Is it possibly the sound ROMs? Is there any way I can test them or the RIOT chip? I don't know a lot about these sound boards, just throwing ideas out there.

#16 32 days ago

I tried a different speaker just for good measure, but still nothing but humming. Black Hole has 2 speakers in the cabinet so I guess it was pretty unlikely both were bad.

The displays just blew a fuse on me again. It's the small fuse on the all in one control board which I could only find from Pascal Janin. Luckily I bought a couple extras but I'm not sure why the fuse blew again. I thought the problem was the little credit display which had a burnt out chip on it. I replace it with a display I had on the shelf which was good and I thought that would solve things... I guess not. Must be one of the other displays. Damn this thing, they were good for a while.

#17 31 days ago

Anyone know anything else I can test or check for? Any help is very much appreciated, thanks.

#18 30 days ago

Have you got a logic probe?

I've never worked on these sound boards but there's some fundamental things you can check guided by some info on PinWiki.

Firstly, there's some sound select signals to the sound board at pins 8, 9, 11, 12 on plug 1 that if you briefly ground should tell the board to play some speech/sound effect. If you very briefly ground any of those pins does anything happen?

If you do this with a logic probe hooked up, do you see pin 25 of U15 (40 pin 6532 RIOT chip on the sound board) pulse low?

#19 30 days ago

Yes I do have a logic probe Quench, thanks. I'll try that when I get back home today and report my findings.

#20 29 days ago

Ok, I tried grounding pins 8,9, 11, 12 and had logic probe on pin 25 of U15. No response at all. In doing that I did notice I only have 4.8volts instead of 5, is that acceptable?

I'm ashamed to admit it because I knew better, but I accidentally grounded pin 10, the 30volt line after checking the other lines first. There was a little spark and I hope it doesn't mean I fried something else... It didn't blow a fuse and I'm still getting noise from the speakers.

#21 29 days ago
Quoted from CanadianGamer:

Ok, I tried grounding pins 8,9, 11, 12 and had logic probe on pin 25 of U15. No response at all.

What logic level was the logic probe indicating on that pin? High or Low?

Are any of the address/data lines on the sound board CPU at U3 pulsing? i.e. is it showing any sign of life?
Is the CPU getting an actively pulsing clock signal at pin 37?
How about the reset signal on the CPU (pin 40), is it High (inactive)?

Quoted from CanadianGamer:

In doing that I did notice I only have 4.8volts instead of 5, is that acceptable?

What voltage are you measuring on the 5V rail at the sound power-supply board? How much voltage are you losing from there to the sound board over the connectors?

#22 28 days ago

Thanks for your patience Quench, and everyone. I've been working on my pins and arcade games for 12 years, but I'm far from an expert at electronics. I had my logic probe hooked up wrong... didn't use a ground from the board so the probe showed nothing at all. I found a ground on the board (test points would've been nice Dave G.) and I was able to read everything you asked about. I didn't find any 5volt line at all on the power supply board, and nothing on the schematics about there being one. I wrote down all the voltages from the board side of the connectors on both boards (sound board, and sound board power supply). Let me know if I'm missing something.

Sound board power supply voltages:
1) 12vdc
2) 30.8vdc
3-4) 13VAC
5) -12vdc
6) 24.8vdc

Sound board voltages:
1) 12.05 vdc
3) -11.8vdc
5) 4.87vdc
10) 30.8vdc

With my logic probe set to CMOS, and pulse:

Pin 25 of U15 does not pulse low when I ground the sound lines, the pulse light flickers once and the light stays on high. There are scratchy noises coming from the speakers when I ground the sound lines, like it's trying to play a sound but is quiet and scratchy.

The address/data lines on U3 are all pulsing and showing low.

U3 pin 37 is pulsing and shows low.

U3 pin 40 is staying high, and inactive.

I hope I've answered your questions correctly and completely, and that it gives you some idea of what the heck is going on with this thing. Thanks!

#23 27 days ago
Quoted from CanadianGamer:

I didn't find any 5volt line at all on the power supply board

Sorry you're right, there's no +5volt from the sound power-supply board. The sound board gets +5V power from the main game power-supply board.

With the game off, disconnect J2 and J3 from the main power-supply board. Leave J1 (lower 9 pin connector) still connected. Power on.
Check the +5V voltage at TP4 on the power-supply board, use TP3 on that board as the ground connection for your multi-meter. If you're still reading under 5 volts there adjust the pot on the board until you get about 5.1 volts.
Switch off, reconnect J2 and J3 and power up.
Check the voltage at TP4 again and the 5 volt rail on the sound board. Do they (very closely) match?

Quoted from CanadianGamer:

Sound board power supply voltages:
6) 24.8vdc

You're no longer getting 32 volts at pin 6 on the connector at the sound power-supply board?

Quoted from CanadianGamer:

Pin 25 of U15 does not pulse low when I ground the sound lines, the pulse light flickers once and the light stays on high.

If the pin normally indicates high, then the pulse LED on your logic probe flickers when you ground a sound line, that's correct behavior. The pulse is probably too short for the Low LED on the logic probe to briefly light up. It means the RIOT chip has received some external sound request and is telling the CPU to do something with it.

The activity you're getting on the sound CPU is indication it's doing *something*, so it's not totally dead.

When you press the sound test button on the sound board, does pin 25 of U15 pulse?
If yes, can you probe pins 5 and 12 of both U19 and U20 on the sound board after pressing the sound test button. These are both digital to analog converter chips. If the logic probe indicates activity on those pins, then it's telling us the CPU is sending sound data to the analog circuits.

#24 26 days ago

I swear I was getting 24.8 last I tested it, and I'm sure I checked it twice to be certain! This game is messing with me, damn gremlins in there.

It is in fact 31.8volts where it should be 24v and I feel like I'm losing my marbles lol. I'm really trying my best to be careful and accurate so I don't waste anyone's time. The control board is a new Pascal Janin all in one board, so the power supply and driver board are all on the control board. The 5volt test point on the control (power) board is reading 4.9volts.

When I press the sound test button, pin 25 of U15 does not pulse. I tested U19 and U20 for the heck of it and there was no pulse, just staying low.

Could it mean the RIOT chip is fried? I thought they were hard to find, but looking on ebay I found this... Seller has a ton of 100% positive feedback.
ebay.com link » Gottlieb 6532 Pinball Riot Chip Nos

#25 26 days ago
Quoted from CanadianGamer:

When I press the sound test button, pin 25 of U15 does not pulse. I tested U19 and U20 for the heck of it and there was no pulse, just staying low.

Could it mean the RIOT chip is fried?

Not necessarily. I was hoping the test button would give us a more graceful way of pulsing the /IRQ line (pin 25 of U15) from the RIOT chip without having to short sound select signals to ground.

Try checking the U19 and U20 activity again, this time when you *quickly* short to ground one of the sound select signals (sound board at pins 8, 9, 11, 12 on plug 1). Also reconfirm pin 25 of U15 pulses when you do this.

#26 26 days ago

Thanks Quench. I tested it again, can confirm that pin 25 of U15 pulse light flickers once and stays high when I quickly short a sound select pin to ground.

Pins 5 and 12 on U19 and U20 all pulse hi/lo when I ground the sound select pins.

#27 26 days ago
Quoted from CanadianGamer:

Pins 5 and 12 on U19 and U20 all pulse hi/lo when I ground the sound select pins.

Ok, so I presume this activity is more than a split second and the pulse hi/lo activity potentially lasts the length of a sound effect?

Start a game, under normal circumstances the game will play background sounds. Check pins 5 and 12 on U19 and U20 again with your logic probe to see if they have activity. U19 probably won't (it's for speech) but U20 probably will (it's for sound effects).

Out of curiosity, have you tried adjusted the two volume pots at the top of the sound board (one for speech, the other for sound effects)? Do they make any difference to hum/static levels?

The sound path from the outputs of the Digital to Analog Converters (U19 and U20) go to two LM741 op-amps (U21 and U22) respectively.
Can you measure the power voltage going to those two op-amps. Black meter lead goes to pin 4, red meter lead goes to pin 7 on those op-amps. You should read about 24 volts DC.

#28 25 days ago

I wrote: Pins 5 and 12 on U19 and U20 all pulse hi/lo when I ground the sound select pins.

Quoted from Quench:

Ok, so I presume this activity is more than a split second and the pulse hi/lo activity potentially lasts the length of a sound effect?

Yes, that's correct, it lasts the length of the sound effect.
.

Quoted from Quench:

Start a game, under normal circumstances the game will play background sounds. Check pins 5 and 12 on U19 and U20 again with your logic probe to see if they have activity. U19 probably won't (it's for speech) but U20 probably will (it's for sound effects).

Yes pins 5 and 12 on U20 go active when a game starts, I didn't check U19.

Quoted from Quench:

Out of curiosity, have you tried adjusted the two volume pots at the top of the sound board (one for speech, the other for sound effects)? Do they make any difference to hum/static levels?

Yes, they both change the level of hum/static from the speakers.

Quoted from Quench:

The sound path from the outputs of the Digital to Analog Converters (U19 and U20) go to two LM741 op-amps (U21 and U22) respectively.
Can you measure the power voltage going to those two op-amps. Black meter lead goes to pin 4, red meter lead goes to pin 7 on those op-amps. You should read about 24 volts DC.

Yes, they both read 23.9 volts.

Thanks again for all your efforts in trying to get sound back in the old beast!

#29 25 days ago

Also did the 9v battery test on the speakers this morning, and they moved as they should. In doing so I noticed that one speaker had it's wires on backwards. I was hoping it would magically work after that, but no.

#30 25 days ago
Quoted from CanadianGamer:

Yes pins 5 and 12 on U20 go active when a game starts

So you're getting activity to the inputs of the U20 DAC. The output of the DAC goes to the U22 op-amp. The output of the op-amp then goes to the R15 volume pot on the sound board. Since you said adjusting that volume pot changes the static/hum, we can presume the volume pot forwards through the amplifier and speaker are working. It's likely there's a breakdown in the two DACs and/or two op-amps. Note, the common trait of the DACs and op-amps are they're powered by +12V and -12V.

If you have an oscilloscope, probe the input (pin 2) and output (pin 6) of the U22 op-amp while in game mode and background sounds are playing. See if you're getting an analog audio signal going in and amplified audio signal coming out.
If no oscilloscope, measure the AC and also DC voltages on both those pins both in game mode (background sounds playing) and attract mode (no sounds playing).

#31 24 days ago

I have an oscilloscope, a small nano model but never learned how to use it. I don't know what it has to be set to, which probe to put where, so I tested DC voltage for now. How do I test the AC voltage on U22? Where do I put the +- leads? If you can help me with the AC and even the oscilloscope I can try to get the readings for you. Thanks.

DCV on U22 attract mode:
pin 2= 1.84
pin 6= -9.46

DCV on U22 game started:
pin 2= 1.23
pin 6= -9.43 (was going up and down a bit)

#32 23 days ago
Quoted from CanadianGamer:

How do I test the AC voltage on U22? Where do I put the +- leads?

In this particular case you put the multi-meter leads the same way as you do when measuring DC, black on ground, red on pin to measure. Only difference is you set the multi-meter to measure AC voltage instead of DC.
The AC voltages on those pins are more interesting for what we're doing.

Quoted from CanadianGamer:

I have an oscilloscope, a small nano model but never learned how to use it. I don't know what it has to be set to

Ah well, with an oscilloscope you have the power to see what the signals look like! It's a much better tool for analysing audio signal problems. When you say "nano model" I presume it's the DSO Nano pocket oscilloscope?

If yes, it looks like it has an auto measurement function, so just start with that.
Hook up the black connector to ground and the white connector to the pins at U22 mentioned above in attract and game mode. Post waveform pictures of each.
Might also be worth taking a snapshot of pin 7 of connector P1 on the sound board. This pin goes to the speaker. Hopefully we'll be able to see the audio hum.

#33 23 days ago

Cool, thanks Quench. Quick question though, do I need to connect the black connector to the ground pin on U22 or just any ground on the board?

Oh, and yes it's a DSO Nano pocket oscilloscope.

#34 23 days ago

I didn't get any reading at all for AC voltage on pins 2 and 6 of U22 with game started.

Here's video of the oscilloscope. I started a game with the ground already connected, and then held the white connector on the pins after starting the video.

Pin 2 of U22 with game started:

Pin 6 of U22 with game started:

Pin 7 of connector A6J1 on the sound board with game started:

#35 23 days ago
Quoted from CanadianGamer:

any ground on the board?

Connect the black lead to any ground on the sound board.

I'm not familiar with the Nano, but it also stores a capture of signals. Might need to tell it to recapture when you start measuring each pin because those images are pretty much the same thing. I presume the blue trace is the input signal of interest, not sure what the pink trace is. I'll have to look it up in the manual.
Might need to get you to take pictures at a different angle or in better light, I cant see the settings info top and bottom left of the LCD screen.

#36 23 days ago

Ok thanks, I don't know what the pink trace is either, it's just always there when I turn on the o-scope. I'll take some pictures of the screen so you can see the settings. I don't know if I can figure out how to tell it to recapture when I start measuring but I'll try my best.

#37 23 days ago

Sorry, I just realised you posted videos of the oscilloscope, not pictures. Ignore the previous part in my previous post about recapturing. I still need to see the areas of the screen being blinded by light.

Looks like the pink trace is a previously saved waveform. Use the down arrow button to go to the "Ex" option on the right, and play with the settings there to see if you can remove view of the saved wave.

BTW, make sure you've got the input connectors hooked up to the probe port on the oscilloscope, not the signal generator port.

The signal generator feature could have been useful to inject an audible frequency into the sound board op-amp to see if the amp is working. I can't see how to adjust the voltage level of the signal on the oscilloscope though so we're not pumping in too much.

#38 22 days ago
Quoted from Quench:

I still need to see the areas of the screen being blinded by light.
Looks like the pink trace is a previously saved waveform. Use the down arrow button to go to the "Ex" option on the right, and play with the settings there to see if you can remove view of the saved wave.
BTW, make sure you've got the input connectors hooked up to the probe port on the oscilloscope, not the signal generator port.
The signal generator feature could have been useful to inject an audible frequency into the sound board op-amp to see if the amp is working. I can't see how to adjust the voltage level of the signal on the oscilloscope though so we're not pumping in too much.

I changed the setting on Ex and it just gives me a snapshot now I guess, plus I lowered the voltage to 10mv from 0.1v as seen in the top left of the screen. The second photo is of the settings as I had them before without anything hooked up, and the third picture is after changing Ex and voltage and testing it with game playing.
IMG_4102 (resized).JPGIMG_4103 (resized).JPGIMG_4107 (resized).JPG

#39 22 days ago

Maybe we should try the signal generator feature to test the amplifier.
Go down to "Sn" on the right side menu of the oscilloscope. Set the Output Frequency to something like 500 Hz
Set the Output Duty to 50%
Hook up the connector leads to the wave out port.

Put the game volume control in the lower cabinet about half way.

Connect the black lead to ground and the white lead to the centre leg of the R16 pot. Do you hear any tone from the speaker - note it might be loud so don't be surprised. If you don't hear it, turn the game volume control up.

If the oscilloscope comes with a second set of connectors, plug it in the "Ch" port of the oscilloscope and hook it up as per Pin 7 of connector A6J1 test. With any luck we will see the signal generated tone frequency on the output of the amplifier.

#40 21 days ago

Ok thanks again. I set the output to 500hz, and output duty to 50%, put the volume control at 50%. The sound generator came through very clear and loud.

The video shows what happens when I touch the second connectors to pin 7, but I'm sure I have the settings wrong? The line disappears when I touch the 2nd connector to pin 7. I held it on, and took it off a couple times.

#41 21 days ago

Ok, so the output amplifier is working.
Take the signal generator back upstream and briefly touch pin 4 of U20. Do you hear any tone from the speaker?
If no sound then briefly touch pin 6 of U22.
Report when you do/don't hear any tone sound from the speaker.

#42 21 days ago
Quoted from Quench:

Ok, so the output amplifier is working.
Take the signal generator back upstream and briefly touch pin 4 of U20. Do you hear any tone from the speaker?
If no sound then briefly touch pin 6 of U22.
Report when you do/don't hear any tone sound from the speaker.

Ok, did that and got sound on both pins.

#43 21 days ago
Quoted from CanadianGamer:

Ok, did that and got sound on both pins.

Was either pin louder than the other?

The oscilloscope videos you initially posted showed what looked like possible audio signals but they were very low in volume. The peak movement was about 200 millivolts.

Can you try the following:
Turn up the game volume control to max volume.
Hook up the oscilloscope "Ch" connection to sense pin 6 of U22 so that you're seeing the activity on the output pin on that op-amp.
Start a game so background sounds are running.
At the bottom right of the sound board there is a special pot marked R13. The bottom of the pot has a small screw for adjusting the amplification of the U22 op-amp. It looks like a multi-turn pot so turn it one way counting the number of times you turn it (so you can return it back where it was). Does the signal height on the oscilloscope waveform increase or decrease? Do you start hearing anything from the speaker?

#44 20 days ago
Quoted from Quench:

Was either pin louder than the other?
The oscilloscope videos you initially posted showed what looked like possible audio signals but they were very low in volume. The peak movement was about 200 millivolts.
Can you try the following:
Turn up the game volume control to max volume.
Hook up the oscilloscope "Ch" connection to sense pin 6 of U22 so that you're seeing the activity on the output pin on that op-amp.
Start a game so background sounds are running.
At the bottom right of the sound board there is a special pot marked R13. The bottom of the pot has a small screw for adjusting the amplification of the U22 op-amp. It looks like a multi-turn pot so turn it one way counting the number of times you turn it (so you can return it back where it was). Does the signal height on the oscilloscope waveform increase or decrease? Do you start hearing anything from the speaker?

We might be getting somewhere!

Pin 4 of U20 was a bit louder than pin 6.

I cranked up the volume and turned the screw in on R13 but it made no difference, so I turned it back to middle then started turning it out. After about 3-4 turns I could start hearing the sounds from the game! I took it out to 8 turns and that was the loudest it got before a loud humming came on and sounds started to disappear. I've centered it back to where it was again for now.

The waveform stayed pretty much a straight line but moved up the scale when I turned R13 out. I still don't think I have the voltage right on the meter, but just guessing. I tried playing with the settings a bit but really don't know what I'm doing yet.

That was very encouraging! Brought a smile to my face at the thought that we might be close.

#45 20 days ago

In game mode, if you screw R13 eight turns out and then adjust the R15 pot on the top of the sound board, do you get an acceptable volume of game background sounds?

Quoted from CanadianGamer:

DCV on U22 attract mode:
pin 2= 1.84
pin 6= -9.46

I just noticed this again from your post #31. That idle DC voltage on the pin 6 output of U22 seems too far negative most likely because of the positive 1.84V on the input pin being amplified. Hmm.

I have a Black Hole in storage that I might be visiting this weekend. If I have time I might take some measurements for reference.

In the meantime with your logic probe, can you check pins 5, 6, 7, 8, 9, 10, 11, 12 of the Digital to Analog Converter (DAC) chip at U20 both in attract mode and game mode and report what the logic probe is indicating. I'd like to see what the default no sound logic levels are going into the DAC, and if they're all pulsing when background sounds are playing.

#46 20 days ago
Quoted from Quench:

In game mode, if you screw R13 eight turns out and then adjust the R15 pot on the top of the sound board, do you get an acceptable volume of game background sounds?

No. I can hear them but the background humming is louder than the sound effects. Some sounds seem to work and some are garbled. I'm attaching a video to show that. If you crank the volume you can hear the background sounds etc.

Here's what I read on pins 5-12 on U20 in attract mode and game started.

Attract:

pins 5-11 were all High, and pin 12 read low, none of them pulsing.

Game started:

All pins 5-12 were pulsing Hi-low. It seemed like some pulsed faster than others, pin 5 may have been the fastest. Not sure if that helps.

#47 18 days ago

Here’s a few photos of the boards just to give a visual of things.

712DE680-9343-4F36-991B-E5BB8CB8F64C (resized).jpeg83522D36-01E3-4FA6-BAC8-759F37C67161 (resized).jpegB600A5B6-21A9-4583-95F5-5722D7081B01 (resized).jpegD7F97615-8287-4777-99CB-B22C6E194232 (resized).jpegF1768FE6-8476-4F74-82F8-2336E3AA499E (resized).jpeg
#48 18 days ago

Didn't read the whole thread......but did you check the dipswitches are working properly? Check them by using the continuity test at you multimeter.

Marco

#49 18 days ago
Quoted from CanadianGamer:

Here's what I read on pins 5-12 on U20 in attract mode and game started.
Attract:
pins 5-11 were all High, and pin 12 read low, none of them pulsing.
Game started:
All pins 5-12 were pulsing Hi-low. It seemed like some pulsed faster than others, pin 5 may have been the fastest. Not sure if that helps.

All data pins to the DAC pulsing while playing sounds indicates that from a digital point of view you're not losing any volume from missing digital sound data (sorry my mind isn't letting me express this in more simpler terms).

Quoted from CanadianGamer:

We might be getting somewhere!

Pin 4 of U20 was a bit louder than pin 6.

Oh, I glossed over this previous comment of yours from post #44 too quickly. If you're saying you had louder tone volume from the speaker when you hooked up the signal generator to pin 4 of U20 compared to pin 6 of U22, then that doesn't seem right. You should have got louder tone from the signal generator on pin 6 of U22 because U22 is an amplifier and pin 6 is its output. BTW pin 4 of U20 is an output that goes directly to input pin 2 of U22.
Can you reconfirm this point? because from your first oscilloscope videos the volume of the background sound at the input and output of U22 is the same, and I expect the output (pin 6) to be louder with the waveform showing more vertical (height) movement.

Also, just confirm that the connectors for the oscilloscope are black and white (as per the manual). Black in this case connects to ground, white connects to the signal of interest.

#50 17 days ago
Quoted from MarAlb:

Didn't read the whole thread......but did you check the dipswitches are working properly? Check them by using the continuity test at you multimeter.
Marco

Thanks very much for the input! I hadn't checked that yet but did this morning and they're good.

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