You're currently viewing posts by Pinsider the_pump_house.
Click here to go back to viewing the entire thread.
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.
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.
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?
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.
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.
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
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
Quoted from Markharris2000:Chris is suggesting troubleshooting the driving logic to the DSP, not the data ROMs.
What does he mean by S2?
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.
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
that's the e
Quoted from PBlank:Just a follow up to my issue. I installed a pinsound board and new speakers and now the volume works fine. I'm not sure if I'll keep the pinsound board in here or put it in another pin, but that being the case that it resolved that issue I'm still trying to narrow down what to check on the original board.
Ship the DCS board off to Chris Hibler
You're currently viewing posts by Pinsider the_pump_house.
Click here to go back to viewing the entire thread.
Wanna join the discussion? Please sign in to reply to this topic.
Great to see you're enjoying Pinside! Did you know Pinside is able to run without any 3rd-party banners or ads, thanks to the support from our visitors? Please consider a donation to Pinside and get anext to your username to show for it! Or better yet, subscribe to Pinside+!
This page was printed from https://pinside.com/pinball/forum/topic/dcs-a-16917-missing-sounds-volume-control-issue?tu=the_pump_house and we tried optimising it for printing. Some page elements may have been deliberately hidden.
Scan the QR code on the left to jump to the URL this document was printed from.
Wood River, IL
