(Topic ID: 327740)

DCS A-16917 Missing Sounds / Volume Control issue

By The_Pump_House

40 days ago


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  • Latest reply 1 day ago by PBlank
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    #1 40 days ago

    I've got a DCS sound board on my bench that does not play the tone/sound as you navigate through the service menus. Additionally, when pressing the up or down volume controls the DMD shows the volume going up or down but the volume from the sound board does not change.

    Outside of these two issues, the board appears to work fine.

    #2 39 days ago

    What is a suitable replacement from digikey for the ST M74HCT374B1 chips at U18 and U19 on the sound board?

    I believe my issue is with the control signal from the MPU getting through the sound board. U18 has been previously replaced on this board with a SN74HCT374N.

    There are a lot of variations in the part numbers for the 74HCT374 on digikey. I realize the first two digits are the manufacturer code.

    #3 39 days ago

    Any 74hct374 will work. I don’t think they used any tight specs for manufacturer specific parts. HCT means the high speed CMOS version, and may be interchangeable with the LS version if you can’t find the HCT

    #4 39 days ago
    Quoted from Markharris2000:

    Any 74hct374 will work. I don’t think they used any tight specs for manufacturer specific parts. HCT means the high speed CMOS version, and may be interchangeable with the LS version if you can’t find the HCT

    I would love a better understanding of how the sound boards work. Is there any advanced documentation/theory/discussion available?

    #5 39 days ago
    Quoted from The_Pump_House:

    I would love a better understanding of how the sound boards work. Is there any advanced documentation/theory/discussion available?

    The Pinwiki article @ https://www.pinwiki.com/wiki/index.php/Williams_WPC#WPC_DCS_Sound_Board (that I am sure you have already read) has an orbital view of how things work.

    Another orbital view is to break the board down into three subsystems.

    1. Digital logic.
    2. Analog amplification.
    3. Power amplification.

    If there is a critical failure in one entire subsystem then the whole system will fail. If you have a partial failure in one subsystem it might be easier to determine the subsystem. They are distinct systems (circuits) in the schematic with defined interface points between them.

    U18 and U19 are the buffer ICs (digital logic interface). These buffer the 8 data bits on the CPU board data bus. If you have a problem with one of these ICs you will usually get "SOUND BOARD INTERFACE ERROR". Odds are good there's nothing wrong with these ICs.

    If you really want to replace the ICs then any of the following will work.

    #6 39 days ago
    Quoted from DumbAss:

    The Pinwiki article @ https://www.pinwiki.com/wiki/index.php/Williams_WPC#WPC_DCS_Sound_Board (that I am sure you have already read) has an orbital view of how things work.
    Another orbital view is to break the board down into three subsystems.

    Digital logic.
    Analog amplification.
    Power amplification.

    If there is a critical failure in one entire subsystem then the whole system will fail. If you have a partial failure in one subsystem it might be easier to determine the subsystem. They are distinct systems (circuits) in the schematic with defined interface points between them.
    U18 and U19 are the buffer ICs (digital logic interface). These buffer the 8 data bits on the CPU board data bus. If you have a problem with one of these ICs you will usually get "SOUND BOARD INTERFACE ERROR". Odds are good there's nothing wrong with these ICs.
    If you really want to replace the ICs then any of the following will work.

    https://www.digikey.com/en/products/detail/texas-instruments/CD74HCT374E/38536
    https://www.mouser.com/ProductDetail/Texas-Instruments/SN74HCT374N?qs=3pnr37ZAbK%252BcZximK15Xdw%3D%3D
    https://www.mouser.com/ProductDetail/Texas-Instruments/CD74HCT374E?qs=HE9hdJajmerxTcu8%252BokVDQ%3D%3D
    https://www.mouser.com/ProductDetail/Texas-Instruments/CD74HCT374EE4?qs=vul0MlC%2Fa1fRe1%2Fdyf%252B3yg%3D%3D

    I am have some missing music, missing tone/sounds when I hit the coin door service buttons in the service menu and while volume controls display volume going up and down on the DMD no volume change occurs. I figured out that U18 and U19 were logic buffers between the MPU and the sound board and figured that some signals from the MPU are not making it through to the correct place on the sound card. Analog and Power amplification work fine so I have a digital logic problem.

    Occasionally I do get a sound board interface error. Ribbon cables are new, same issue exists with another MPU installed, issue goes away when I swap sound boards.

    #7 38 days ago

    Confirmed that:

    U18 and U19 pins trace to correct pins on sound board J1 header and U10, U11, U12, U13, U14 and the ADSP at U1, new ribbon cables, I have swapped U16 with a known good chip from another board.

    Studying the board there has been chips replaced previously at

    U13, U14, U15, U18, U29, U1

    And C45 and C37 have been removed

    So I'm thinking someone tried to tackle this problem previously and failed.

    #8 37 days ago

    Got an hobby oscilloscope (hand held hantek) and just spent way too long reading about op amps.

    I just want to learn enough to understand the basic function of the boards

    #9 37 days ago

    The DSP on the board is responsible for volume. The MPU will command a volume setting to the DSP. I’d be surprised if there wasn’t a feedback message to the MPU; a closed loop control system.

    The DSP does all of the “digital” work on the board as DumbAss was saying above.

    The DSP accepts sound commands from the MPU. It then pulls the sound data from the ROMs and pipes it through the digital to analog pipeline.

    Sound ROMs are checksumed by the DSP.

    But S2 can be the wrong S2 and the DSP would never know.

    I’d verify S2 as the next step.

    Chris Hibler - CARGPB #31
    Http://chrishiblerpinball.com/contact
    http://www.PinWiki.com/ - The new place for pinball repair info

    #10 36 days ago
    Quoted from ChrisHibler:

    The DSP on the board is responsible for volume. The MPU will command a volume setting to the DSP. I’d be surprised if there wasn’t a feedback message to the MPU; a closed loop control system.
    The DSP does all of the “digital” work on the board as DumbAss was saying above.
    The DSP accepts sound commands from the MPU. It then pulls the sound data from the ROMs and pipes it through the digital to analog pipeline.
    Sound ROMs are checksumed by the DSP.
    But S2 can be the wrong S2 and the DSP would never know.
    I’d verify S2 as the next step.

    Chris Hibler - CARGPB #31
    Http://chrishiblerpinball.com/contact
    http://www.PinWiki.com/ - The new place for pinball repair info

    Thanks Chris. I swapped all roms with known good roms from one of our other Indys

    #11 36 days ago
    Quoted from The_Pump_House:

    Thanks Chris. I swapped all roms with known good roms from one of our other Indys

    Chris is suggesting troubleshooting the driving logic to the DSP, not the data ROMs.

    #12 36 days ago
    Quoted from Markharris2000:

    Chris is suggesting troubleshooting the driving logic to the DSP, not the data ROMs.

    What does he mean by S2?

    #13 36 days ago
    Quoted from The_Pump_House:

    What does he mean by S2?

    WPC-95 refers to the sound ROMs as S2 through to S7. WPC-DCS refers to the sound ROMs as U2 through to U9. Chris is referring to U2 on your DCS board.

    U2 contains the code executed when the DSP processor comes out of reset. One of the tasks the code performs is to checksum the other ROMs in the system. Those other ROMs are typically static (fixed) as they contain sampled sounds. The code itself is dynamic. It cannot checksum the entire contents of itself because the checksum itself would cause the checksum to change. Confused yet? This is what Chris was trying to say with "But S2 can be the wrong S2 and the DSP would never know."

    If you have already swapped with known good and the problem persists then you have a problem elsewhere, presumably in the digital logic side. If this were a pre-DCS board, it could have been near the analog boundary but in DCS, the DSP (ADSP2105) is responsible for the generation of all signals to the DAC (AD1851).

    #14 36 days ago

    Another thing to look at are the DIP sockets. If the board came out of a re-import game it could have been sitting in a shipping container for quite some time. If so the DIP sockets could be oxidized and corroded. I've had to replace DIP sockets if they are like that.

    #15 36 days ago
    Quoted from DumbAss:

    WPC-95 refers to the sound ROMs as S2 through to S7. WPC-DCS refers to the sound ROMs as U2 through to U9. Chris is referring to U2 on your DCS board.
    U2 contains the code executed when the DSP processor comes out of reset. One of the tasks the code performs is to checksum the other ROMs in the system. Those other ROMs are typically static (fixed) as they contain sampled sounds. The code itself is dynamic. It cannot checksum the entire contents of itself because the checksum itself would cause the checksum to change. Confused yet? This is what Chris was trying to say with "But S2 can be the wrong S2 and the DSP would never know."
    If you have already swapped with known good and the problem persists then you have a problem elsewhere, presumably in the digital logic side. If this were a pre-DCS board, it could have been near the analog boundary but in DCS, the DSP (ADSP2105) is responsible for the generation of all signals to the DAC (AD1851).

    Thank you for the clarification. I assumed that by S2 he was referring to the sound roms (particularly U2) but the reply from mark confused me.

    I always assumed I had a logic issue, perhaps a bad DSP? I was kind of focused on the signal between P1 and the path to the DSP.

    #16 35 days ago

    Ok, you will have to forgive my soldering skills.

    I did find a broken trace on the bottom of the board between u18-2 and u12-10. I had previously traced it fine. I decided to put a little stress/tension on the board and retrace the logic traces.

    443CA97D-527A-4F97-AC22-41875CFADBD0 (resized).jpeg
    #17 35 days ago

    socketed and replaced U17 (74F00) and I now have a perfectly working sound board

    #18 35 days ago

    Switching to another 16917 sound board I have that was hacked to hell and back by someone. Not too worried about saving the board but would still like to solve the puzzle

    https://pinside.com/pinball/forum/topic/judge-dredd-a-16917-misc-sound-issues#post-6979180

    1 month later
    #19 3 days ago

    Hey I hope nobody minds me jumping in on this thread with my similar, if not same issue. If so I'll remake my own post. I have searched around and seen other variations of this issue, but people seem to have different board variations, and this seems to be the most recent post on this?

    So I just got my Dredd and seem to have the same issue and I'm trying to trouble shoot.
    -Audio plays fine, volume button + & - work fine, but the Volume wouldn't go below 8
    -Changed the Minimum volume override in the test adjustment section to be "Yes".
    -Volume levels on dmd now allow to go below 8, but there is no change in the volume level at all
    -Also can not find any other additional volume control added in the backbox

    I'm trying to find more pictures of Judge Dredd audio boards like mine to see if there's anything visually different. If anybody has or is willing to post pictures of their Dredd sound boards it would be appreciated, and any additional advice to track this down.
    Here's a picture of mine. The 2nd picture I unplugged the cables for a better view:

    IMG_0626 (resized).JPGIMG_0658 (resized).JPG
    #20 2 days ago

    Your soundboard is like every other DCS soundboard. There was no variation in that board over the run of DCS games.

    There are two ceramic capacitors adjacent to the heat sinks, which are sometimes removed. Yours have already been cut and are out of circuit.

    Is the volume excessively loud when you set it below eight?

    Chris Hibler - CARGPB #31
    Http://chrishiblerpinball.com/contact
    Thank you for checking out the PinWiki - http://www.PinWiki.com/

    #21 1 day ago

    Yea it’s loud. It won’t lower or raise at all despite the volume bar changing on the dmd when I try.

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