(Topic ID: 277844)

Pinbot System 11A no sound issue - Please Help

By Oddball49

3 years ago


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    #1 3 years ago

    Hey all, I am trying to get an old pinbot up and running for the first time in 20+ years. I am getting no sound at all, including a lack of the startup tones. Can somebody give me some insight to what I might try?

    - First, know that the game does enter the attract mode correctly, and the game is playing correctly as well.
    - I am getting a hum through the speakers so I would assume the amp and speakers are working. There is a change in pitch to the hum as various lights and solenoids fire.
    - There is no battery acid damage on this MBU, and I have removed the battery holder and installed a U25 RAM replacement to hold scores.
    - I checked the wiring multiple times and every thing seems to be in order.
    - I re flowed all of the header pins involved.
    - I have all new Pinbot sound Roms installed.
    - U23 gets really hot, like, to the point where you can't touch it. I heard that U23 can be diagnosed by the sound test, but that would require the power on tones to be working correct?

    - To confirm, no music, no voices, no sounds

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    #2 3 years ago
    Quoted from Oddball49:

    - U23 gets really hot, like, to the point where you can't touch it.

    That's not good. You will need to replace this first. While the chip is removed, check all the circuit points to it, for proper voltage, continuity...before installing the replacement. Hopefully, it's just this IC that is killing the works.

    Wayout

    #3 3 years ago

    Do you have a logic probe? Put the game in sound test and test for pulses on the PIA that processes the sound. I do agree that the hot chip is totally suspect. If you don’t have board work experience proceed with caution.

    Did the sound work before you installed the NVRAM?

    #4 3 years ago
    Quoted from kermit24:

    Do you have a logic probe? Put the game in sound test and test for pulses on the PIA that processes the sound. I do agree that the hot chip is totally suspect. If you don’t have board work experience proceed with caution.
    Did the sound work before you installed the NVRAM?

    When i first received the machine, i gave it a dry run. Some sound came out but it was a garbled mess. (this was roughly 3 years ago) As i fixed up the GI and other aspect of the machine, the sound stopped working altogether. I do have a logic probe, but I have no idea what I am looking for. I understand that I simply ground the black pin, and probe various points with the other while looking to see the what the "activity" looks like on various points, but I am not sure how to interpret the results.

    As far as doing board work, I am very competent, but not excellent. I have been fixing various boards now for 5 years or so. I would put in a socket if I were to remove U23.

    #5 3 years ago
    Quoted from Oddball49:

    When i first received the machine, i gave it a dry run. Some sound came out but it was a garbled mess. (this was roughly 3 years ago) As i fixed up the GI and other aspect of the machine, the sound stopped working altogether. I do have a logic probe, but I have no idea what I am looking for. I understand that I simply ground the black pin, and probe various points with the other while looking to see the what the "activity" looks like on various points, but I am not sure how to interpret the results.
    As far as doing board work, I am very competent, but not excellent. I have been fixing various boards now for 5 years or so. I would put in a socket if I were to remove U23.

    You can put in sound test and test for pulses on U9 pin 19. I seriously doubt you will get pulses there, as the problem is probably more upstream. If you do get pulses there, it is further downstream. U23 is the sound ram. U9 is the PIA that does sound and speech. U24 is the processor for the sound / speech. Any of these 3 (or others) could be suspect. Best place is to start as far upstream as you can and test for pulses. When you press the sound diagnostic switch, what do you get?

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    #6 3 years ago

    Also, based on your comment, you may not have a logic probe. You ground the black and connect the red to 5V and measure with the probe.

    https://www.amazon.com/Elenco-Electronics-LP-560-Logic-Probe/dp/B000Z9HAP4/ref=sr_1_3

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    1 month later
    #7 3 years ago

    Hi,
    I'm starting up this thread again. My Pinbot was working perfectly. After moving it had no sound, plays perfect other than that. I still have hum from the speakers. I turned the volume up and with my head against the speakers I do hear sound. I went through the sound tests and it appears to play all the music and sound. It is just whisper quiet and completely distorted making it hard to recognize the different ones. But I'm 100% sure it is playing them. I reseated all the connectors, no change. I did notice that U9 Sound Processor chip gets hot. That is as far as I've explored as I'm not that experienced at repairs on this machine. I have a multimeter and basic understanding of electronics. Please can some folks guide me as to how to proceed to diagnose what is wrong. I do have a High Speed and was wondering if I could install the sound board in that to test it?
    Thanks!!!

    #8 3 years ago

    Often this can be a problem with the attenuation circuit in this series, since the volume control is in the middle of the final output mix and a long cable is used to connect the volume potentiometer in the front of the cabinet to the backbox ircuitry. The other main causes can be final amp, cable out & speaker. Eliminate the external possibilities by substituting a known good speaker and cable, and a known good potentiometer and cable. If it still doesn't work, troubleshoot the final audio amp circuit.

    #9 3 years ago

    Exactly what is the final audio amp circuit and how would I proceed to troubleshoot it?

    #10 3 years ago
    Quoted from vintageamusement:

    Exactly what is the final audio amp circuit and how would I proceed to troubleshoot it?

    Final audio amp would be the "power amplifier" which feeds a signal to your speakers. The tricky thing wqith a Williams System 11A is that some things happen on the CPU, and some on the background sound and speech board. Your speaker connections are to the CPU board 1J15 (which, by the way - if you haven't you should check that connector) there are some other small filtering components here, and a connection to the cabinet volume control at 1J16, but the actual power amp circuitry including the integrated circuit amplifiers (TDA2002) are located on the background sound and speech board. Ideally, you would want to have basic audio amplifier troubleshooting training or experience, and use an oscilloscope to check the signals at various points in its signal flow to determine where the signal is getting "lost" - then find out why (bad component, open connection etc...)

    #11 3 years ago

    Can I test the sound board only in Williams system 11A? Or can I also try in 11B, 11C titles?

    #12 3 years ago
    Quoted from vintageamusement:

    Can I test the sound board only in Williams system 11A? Or can I also try in 11B, 11C titles?

    The short answer is *probably not*. Williams made a lot of changes in sound boards from game to game.

    #13 3 years ago
    Quoted from vintageamusement:

    Can I test the sound board only in Williams system 11A? Or can I also try in 11B, 11C titles?

    You can, at least to some degree. How that actually works depends on how populated your sound board is. They have several "channels" for the sound and sometimes, as noted above, not all of the channels were stuffed at the factory.
    --
    Chris Hibler - CARGPB #31
    http://www.ChrisHiblerPinball.com/Contact ... for board repairs
    http://www.PinWiki.com - The Place to go for Pinball Repair Info

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