(Topic ID: 307816)

Williams System 11 Startup DONG then nothing...Help

By WesleyB

4 months ago



Topic Stats

  • 9 posts
  • 6 Pinsiders participating
  • Latest reply 4 months ago by WesleyB
  • Topic is favorited by 2 Pinsiders

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#1 4 months ago

I have a pinbot with a very odd sound issue I am trying to narrow down and possibly fix or send off to get fixed. When I bought this machine last week, the owner told me that the machine had no sound at all, just a loud hum coming out of the speakers. He had bought an extra sound board in hopes that would fix the issue and it did not. After some cleaning, reseating of chips on the sound board and MPU and getting the red, black, white cables plugged into the correct sockets, I can hear the startup DONG but it is very faint with the volume all the way up (I adjusted the POT on the sound board and no real change). The volume knob "works" as in it increases and decreases the hum. There are no other sounds after the initial dong. I have gone in the menu and played sounds as well as done the sound test button on the MPU.

I am at a loss and this is my first system 11 board. I have done some hunting on here and cannot find my issue...anyone want to help me out and point me in the correct direction to start diagnosing? I want to make sure if I have to send this off that the issue lies with the MPU or sound board and not something else that I am just overlooking because I have not worked on these before. I have good soldering skills and have a basic DMM and oscilloscope and know how to look for signals. Thanks in advance for any help!

I have a video of what it does but did not really think it would help all that much since it only just does the dong at startup. Let me know if I should post that up.

#2 4 months ago
#3 4 months ago

What happens when you push the sound test button on the left of the MPU board? (Does system 11a have one?)
My only experience with tracking a lost portion of audio on an 11b game, music but no voice, was, in sound test via coil door buttons, music worked but no voice was heard and there was a noticeable hum. Hooked MPU and sound board up on a bench and pushed the sound button on the MPU. Alternates a high beep then a low beep. Only one beep was working. Looking at schematic and using a scope, I traced it to a $1.79 OP amp. Signal was going in, but nothing coming out. Replaced it, hum went away and call outs were back. Owner had the game for years and didn't realize it had call outs.

#4 4 months ago

Thanks for the replies. No sound is heard when pushing that button.

The link posted looks promising…I need to get the computer power supply out and hook it up on the bench.

#5 4 months ago
Quoted from WesleyB:

it only just does the dong at startup

This probably doesn’t help, but I had the same when I first started my Pinbot up.. turned out to be 2 blown fuses because a faulty GI wire connection and because of a leaf switch that was stuck.

#6 4 months ago
Quoted from Seamlesswall:

What happens when you push the sound test button on the left of the MPU board? (Does system 11a have one?)
My only experience with tracking a lost portion of audio on an 11b game, music but no voice, was, in sound test via coil door buttons, music worked but no voice was heard and there was a noticeable hum. Hooked MPU and sound board up on a bench and pushed the sound button on the MPU. Alternates a high beep then a low beep. Only one beep was working. Looking at schematic and using a scope, I traced it to a $1.79 OP amp. Signal was going in, but nothing coming out. Replaced it, hum went away and call outs were back. Owner had the game for years and didn't realize it had call outs.

I would vote Op Amp too, I’m guessing an LM324? - I’ve replaced them on Atari games of the same era they go bad and the sound is faint and other weird issues.

#7 4 months ago

Update…mpu sound section is pretty much not partying. We hooked both of my sound boards up to a good mpu and nothing from one and one had background music that was directly from the card (no mpu sounds). My other card was very faint on all fronts.

I took the good card that my friend graciously lent for testing and it works with the music but no sounds on my mpu.

I’ll be sending my mpu and both sound cards off for repair!

One more interesting thing, I replaced the power supply with a new one and all the ground noise is gone! I will update once I have more info on what was wrong and what the fix was. Thanks for the help!

#8 4 months ago

Keep us updated.

#9 4 months ago

Ok, I broke down and got the newer rottendog MPU for the system 11 and installed it tonight. Here is what happened.

put the maybe dead card in. no bong. Took it out

put the known good one in and got the dong and sound test worked but music was super faint. I took the new rom chip i got from a vendor here in the board and I then got sounds but VERY faint music. amp was working since i got the dong and it was loud. This is when i started shooting in the dark. I took the YM3012 out of the other one I had and put it in the working(ish) unit. WORKS! Missing sounds 1-5 but 6-7 were there. I then placed the yamaha m2151 and that cleared up that issue.

I have sound on all fronts. I have to mess around with the levels but i can look past that for the sweet sweet sound.

Question for yall. Would it be worth sending these boards off (sound and MPU) to get repaired and keep them as a spare or sell them down the road?

Thanks for the advise and this group is awesome~!!!!

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