(Topic ID: 241310)

EBD Sound out occasionally on start up


By Calipindave

1 year ago



Topic Stats

  • 23 posts
  • 4 Pinsiders participating
  • Latest reply 1 year ago by Calipindave
  • Topic is favorited by 1 Pinsider

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#1 1 year ago

Hi guys. I have been resurrecting an EBD for the last month or so and have it up and running. Generally speaking everything works great but I did work through some hacked wires and bad connectors.

Every 10th time or so (randomly) I will power on the machine from off and there will be no sounds whatsoever of any kind. If I turn it off and on again it will generally come back with sound.

All the sounds and speech are crisp clean and loud. As part of the initial resurrection I replaced all the caps on the sound board. The speaker is new. I replaced the sound pot on the front door. All the pins on the headers of all the boards have been re flowed but only a few connectors replaced. I have not been able to confirm if the no sound circumstance can be remedied by wiggling or pulling connectors.

Any help or direction would be appreciated.

Thanks

Dave

#2 1 year ago

Also meant to mention that u2 u6 u8 u9 and u11 are all new

Dave

#3 1 year ago

Dirty pots? If you haven't, try cranking the volume controls back an forth a few times to clean them.
Repinning the connectors couldn't hurt either.

#4 1 year ago
Quoted from BigAl56:

Dirty pots? If you haven't, try cranking the volume controls back an forth a few times to clean them.
Repinning the connectors couldn't hurt either.

Thanks Al. All the pots have been replaced (2 on the board and 1 on the door). I will definitely check the connectors next time it comes on silently.

Dave

#5 1 year ago

Take a wire brush (or toothbrush) and brush all the pins. Check for any loose pins or connection wires as well.
You have essentially replaced everything else except the sound chips, so pins are the next logical choice.

#6 1 year ago

Could be the reset circuit is flaky and doesn’t always properly reset. When this happens the cpu won’t run and you get no sounds.

#7 1 year ago

Pinwiki has a section detailing the reset circuit. You can check U1 pin 40 with a logic probe. On power up it should jump from low to high. Repeat the test over and over to ensure you are getting a consistent reset.

#8 1 year ago
Quoted from jj44114:

Pinwiki has a section detailing the reset circuit. You can check U1 pin 40 with a logic probe. On power up it should jump from low to high. Repeat the test over and over to ensure you are getting a consistent reset.

Thank you. Sounds like a logical idea () since this is an occasionally boot up issue.

Question: everything else works fine just no sound. Is that still a possible reset issue?

Also I don’t have a logic probe. Any other way to test ?

Dave

#9 1 year ago
Quoted from jj44114:

Pinwiki has a section detailing the reset circuit. You can check U1 pin 40 with a logic probe. On power up it should jump from low to high. Repeat the test over and over to ensure you are getting a consistent reset.

Ok... just checked it before leaving and it turns out there is no chip at all in u1, just the socket.

The game generally runs fine without it.... should I get one in there?

It booted up again without sound. I checked connectors and it didn't make a difference. LED on MPU glows faintly after the boot sequence. Game starts up and plays fine just no sounds of any kind.

I booted it again no sound.. started a game and then got speech and target response but no background noises.. put a two player game on and when second player started got all sounds..

Dave

#10 1 year ago

No U1? That’s the processor for the board. Without it you would have no sounds at all.

#11 1 year ago

Not the MPU, U1 on the sound board. Your problem is not on the MPU.

#12 1 year ago
Quoted from jj44114:

Not the MPU, U1 on the sound board. Your problem is not on the MPU.

Got it. Problem may be u1 on sound board.

Dave

#13 1 year ago

Hold on. You do the reset test earlier mentioned on the sound board using U1. U1 is probably good.

#14 1 year ago
Quoted from jj44114:

Hold on. You do the reset test earlier mentioned on the sound board using U1. U1 is probably good.

Still have to give that a try. I don’t have a logic probe. Is that something that can be seen with a good mm?

Dave

#15 1 year ago

Yea. Sound board red lead on pin40 of U 1 black lead on ground. You should see a voltage spike when you power up. Keep repeating a bunch of times to see if it’s consistent. The reset goes very low voltage for an instant then should stay about 5 volts.

#16 1 year ago

Ok checked with the DMM. Btw pin 40 goes to TP 12 so it made it easier.

I’m not sure what I am seeing. Almost ever time it booted I could see oL and a low reading (like .134) before settling in each time between 5.15 and 5.2.

One time it booted with no sound I saw the oL and no other reading and then 5.13.

It never spiked above 5.2 VDC that I could tell.

Dave

#17 1 year ago

Those readings make sense. When it booted with no sound it looks like it didn’t go low or no reset. Pinwiki lists all the components in the reset circuit. Check those and especially the big cap, I think it’s C1.

#18 1 year ago

Also watch led on the sound board when you power on. Are getting 5 flashes every time? Even when you boot and don’t have sound?

#19 1 year ago
Quoted from jj44114:

Also watch led on the sound board when you power on. Are getting 5 flashes every time? Even when you boot and don’t have sound?

I powered it on and off about ten times in a row. All came on with sound and each with 5 flashes. I couldn’t watch the voltage at the same time.

When you refer to the reset circuit are you talking about the MPU board?

All the caps on the sound board were replaced as well as the two big ones on the SDB.

Dave

#20 1 year ago

The reset circuit on the sound board. Go to pinwiki and look at Squawk &talk troubleshooting.

#21 1 year ago

From pinwiki: Make sure that the reset on the CPU chip starts low briefly and then goes high. With a logic probe, check pin 40 of U1. If the reset does not go high, suspect C1 (47uF 25v), CR1 (1N4148), R1 (27K 1/4w), U15 (74LS14), or possibly U17 (74LS155).

#22 1 year ago
Quoted from jj44114:

From pinwiki: Make sure that the reset on the CPU chip starts low briefly and then goes high. With a logic probe, check pin 40 of U1. If the reset does not go high, suspect C1 (47uF 25v), CR1 (1N4148), R1 (27K 1/4w), U15 (74LS14), or possibly U17 (74LS155).

Perfect.

I will check that out.

Dave

#23 1 year ago
Quoted from jj44114:

From pinwiki: Make sure that the reset on the CPU chip starts low briefly and then goes high. With a logic probe, check pin 40 of U1. If the reset does not go high, suspect C1 (47uF 25v), CR1 (1N4148), R1 (27K 1/4w), U15 (74LS14), or possibly U17 (74LS155).

Latest update:

C1 is new from previous work. R1 measures 25K or so... seems in spec. I replaced CR1...

It seems though that the "reset" advice from pinwiki is about the LED being stuck on. Whether or not the sound comes on, the LED never stays lit so we are getting deeper into the boot sequence...

One time on bootup last night, I thought I only got 4 flashes (I was trying to watch the LED and the MM at the same time so I am not 100% sure) which would indicate problems with the speech chip at u8.

I pulled u8 and it was severely tarnished so I cleaned it up..

So far after about 15 cycles sound has been coming on without issue..

We'll see.

Dave

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