(Topic ID: 239879)

wpc pre dcs sound board no bong


By Hawk007

52 days ago



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  • 33 posts
  • 4 Pinsiders participating
  • Latest reply 37 days ago by Hawk007
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bong on DAC (resized).png

#1 52 days ago

Calling wpc sound gurus..I have a cftbl sound board [was from a gilligan originally] that will not bong. The sound/voices all work in test.

Also tried it in a gilligan [ironically with a dr who sound board in it with gilligan roms] with its roms and same thing. No 'all good start up bong' but sound still works normally.

Which eliminates speakers,cables,roms. Cpu ic was swapped and 6264 swapped for known good examples. to no avail.
Anyone seen this? Know how to get my bong back?
Has good clock signals, power and reset but no bong. Also some of the address lines and data lines read different than a known good sound board in game over state.

But yet it works....so odd. I also checked the 74ls374chips with a dmm and they test good. Dmm's can lie though so...

Just curious if anyone has had or repaired this issue before.

#2 52 days ago

Bump for day crowd

#3 51 days ago

update: All comparisions made to a working board....
Pin 32 of the sound board cpu should be high but is high low pulse and all the data lines should read low pulse but read high low pulse except D7 which reads high pulse
Thoughts before I dig deeper?

Thanks in advance for any info.

#4 51 days ago

Bump for evening crowd

#5 50 days ago

If it works, is the bong really necessary?

My guess is that the amp isn't kicking in soon enough - maybe bad cap or something that is keeping anything from being output until something warms up.

#6 50 days ago

Well its not absolutely necessary but I like to have everything working the way it should be. Interesting thought on the caps. I had the same idea. Got most, if not all of them here now so I will try that before anything else.
There has to be something wrong as it should bong no matter what.

The sound works right away due to their being no batteries it boots to the factory settings page and when you hit any buttons it makes sound. Just no bong.
And you can hear the turn on pop or [distorted click] and background clicks as it boots through the speakers plain as day as you should.
Strange .

#7 50 days ago

How about posting a picture of front and back of the board.

#8 50 days ago

from Pinwiki
6.4 Power-On LEDs and Sound Tones (Bongs)

When the game is booted, several LEDs in the backbox will light, and the game may provide sound "bongs" to indicate diagnostic status.

A properly booting WPC game will show a "progress bar" on the DMD along with a "ticking" sound which results from a series of reset signals being sent to the sound board. After a successful boot, the sound board will create a single "bong" tone.

#9 50 days ago

So potential issue with a reset or blanking signal on the sound board

#10 50 days ago

Awesome. thanks. I read that on pin wiki also.

This has great reset signal and has only had the tants replaced [by me] along with the tl084's have been socket-ed by a previous owner. I pin checked them and all good.

Be nice if they included a blanking LED so you could tell at a glance if that's the trouble. I would post pictures but my camera SUCKS.... The board is nice and clean. No damage or anything. Not like the other working board I am comparing too. The tants blew so hard on that board there was a small pit in the board. Yikes!

SO now to track down which component is holding up the mix.

It also plays the right sounds when it should in game so u29 and u30 should be ok or we'd be getting wrong sounds.

So strange that it works otherwise. but that could be temporary if what is causing the no bong gets worse. Thats why I am not playing it until I get it figured out.

Thanks for all the info so far guys. Anything and everything helps. Cheers!

#11 49 days ago

Likely NOT blanking or reset signal -
Mainly because the 'bongs' are produced by the CPU on the audio board. Resetting the RESET line would just cause the board to boot up from scratch, and give you a 'bong'.

You can test this by manually resetting the CPU on the audio board manually, after the game has booted and you get other audio. You can do this by connecting Pin 37 of U13 (the CPU) or Pin 2 of U21 (Inverter) to +5V momentarily.

If you get a bong, then it's something that is taking a while to warm up on power on. If you don't, then it is something else.

#12 49 days ago

Thanks again for chiming in ! Appreciate the posts... And good call. The blanking signal from the asic on the MPU board terminates at pin 27 on the Sound Board J506 ribbon header and goes no where on the sound board. The reset signal is good for sure. tested at pin 13 on U26 and pin 37 of cpu chip. Both are high as they should be.

So as you say has to be something 'else' sigh...

Do you not momentairly ground the pin 37? As its high already. I am almost positive its something else though mainly because it gets no bong even when on for an hour and reset /cycled on/off really fast.

So likely not a warming up issue correct?

#13 48 days ago
Quoted from Hawk007:

Do you not momentairly ground the pin 37? As its high already.

I was basing it off the schematics, which could be wrong. On the 6809 CPU, it's listed as a RESET (high signal=RESET), not a /RESET (low-signal=RESET). Again, I could have been wrong.

Quoted from Hawk007:

I am almost positive its something else though mainly because it gets no bong even when on for an hour and reset /cycled on/off really fast.
So likely not a warming up issue correct?

I would, then, reburn **ALL** EPROMS. If that doesn't fix it, swap out 6809 CPUs.
If THAT doesn't work, then it's possible you're NOT getting all the audio you should be - i.e. you have a bad Yamaha chip.

#14 48 days ago

Good thought. Re-burned eproms and am using a good board to compare too. Swapped known good cpu, ram,eproms,both sound chips. Still same thing.
I just let the good sound board sit in the game running for 10 mins and I think I do not get the rotating attract sound after the initial attract theme song on the bad board like I do this one.

Kind of like its onboard timer or crystal is bad so it does not know when to initiate the attract sound. Thinking may be U22 74ls04 or X1.

Off to test U22 with a dmm. Can you test the crystal at the 2151 pin 24? OSC signal? The 74ls04 connects to the CPU ic R/W signal too and its readings are off compared to a good board with a logic probe.

I sense a bad fish...lol

#15 48 days ago

tested 74ls04 with DMM it reads good. hmmm not concrete results of course as its not under load. Thoughts?

#16 47 days ago

just metered out the eproms to each other and all is good. Now to check their paths to the cpu and ram.
any other thoughts?

#17 46 days ago

WPC sound boards will not boot without the ribbon cable plugged in. Some say they will ....but they do not.

And checked all of the ic's with a dmm on the board and all test good. Hmmm. Time to check the ribbon cable header......
Thoughts?

#18 46 days ago
Quoted from Hawk007:

WPC sound boards will not boot without the ribbon cable plugged in. Some say they will ....but they do not.

This is correct, because of a pull-up resistor on the RESET line. Without the MPU to pull he RESET to 0v, the CPU will stay in reset. You can ground pin 37 on U13 to cause the CPU to start executing code.

And checked all of the ic's with a dmm on the board and all test good. Hmmm. Time to check the ribbon cable header......
Thoughts?

Not sure how you're checking without other parts of the circuit getting in the way, but I would try replacing (or switching out) the YM chips, see if that changes anything.

#19 46 days ago

tried switching both ym chips. no difference.

And I was checking the ic's to a schematic with DMM in diode test. they will usually show a short or a bad/funny reading if IC is bad. Best to test against another IC used in the same circuit that works and compare.

Not always effective as its not under load.

#20 46 days ago

Just checking U20 and U26 again and both have consistently lower readings than comparable chips on a 'good' board. Seems like something is dragging down the pins or one of the IC's are dragging down the other as they are tied together at pin 6.
thoughts..

#21 46 days ago

something interesting.....there is a slight darker discoloration under the U32 IC. I think the caps are really bad right by it. Gonna try replacing the smaller caps on this board. They need it anyways.

For U32 I used DMM on diode test and I get different readings from a known good sound board so I will replace the elec. cap tied to it and the rest while I am at it and see if the readings change.

#22 45 days ago

Another something interesting. All components attached to 12v+ are reading off compared to a good board. resistors,caps,ic's. ETC. Thinking a cap is pulling this awry. Off to change smaller value caps.

#23 45 days ago

Ok . Update. Attract sounds work and board seems to function fine. BUT there is no bong noise EVER. If you remove an eprom off of the sound board there is no bongs at all to denote what eprom is missing and there is on all my other wpc games.
What actually makes the bong noise on these boards?

#24 45 days ago
Quoted from Hawk007:

Ok . Update. Attract sounds work and board seems to function fine. BUT there is no bong noise EVER. If you remove an eprom off of the sound board there is no bongs at all to denote what eprom is missing and there is on all my other wpc games.
What actually makes the bong noise on these boards?

The three sound roms contain the Sound OS (for the processor there) and the raw sound data itself. (Which is why when I said to heck the EPROMS, check the checksum of them, not electrical readings off of them. If, for some reason, your CFTBL sounds are running an early/test version of the Sound OS, anything could be happening. By checking the checksums, you can verify that what is programmed on them is accurate.)

#25 45 days ago

I did check the eproms my friend. First thing I checked actually. They are for sure 100% good. If you read back. I have tried 3 sets of eproms in this board. No bong. 2 gilligan sets and a cftbl. All roms work in their games.

And if you pull u15 on my other wpc games the game goes bong bong bong and displays rom error. If you do it on this sound board. nothing...dead silence and you get the rom error but no bong.

no bongs ever! Must be the DAC chip making the noise. Maybe a bad section/leg?

#26 42 days ago

weekend bump. Anyone know what actually generates the bong noise? Or is it a rom file on U18 in the sound board OS?
Still no bong...sigh

#27 40 days ago

anyone? Bueller..bueller.. lol

#28 40 days ago

Sorry, I gotta wipe my hands with this one... Reached the end of my skills on narrowing down what it could be.

Still think it's a time-delay thing going on. For example, never mentioned if you're using stock speakers, or a mod speaker set or something. Or if the caps on the backbox speakers have been modified, etc. And there are so many small things it could be.. For *THIS* issue, I don't think it's worth it.

GOod luck though, I'm following the thread, in case you do ever get it figured out!

#29 40 days ago

No sweat man. Thanks for your time and thoughts either way. Cheers!!
I tried the sound board in a gilligan and in a creature. That eliminates many things. Plus all stock speakers in both games and nothing has been modified from factory.
I have a good board i tried in both games too so that rules out everything but the actual sound board. Must obviously be a component pulling something awry.. :-/ I really dislike it when things are not right so I will still keep hunting on the cause and repair of this issue.

Stay tuned folks..same Hawk time..same Hawk channel. lol

#30 39 days ago
Quoted from Hawk007:

weekend bump. Anyone know what actually generates the bong noise? Or is it a rom file on U18 in the sound board OS?
Still no bong...sigh

Been following your post, but lately I unfortunately haven't been able to spend some time with my machine. I remember seeing the bong show up on one of the four channels while troubleshooting my T2 audio board.
I would agree with you and suspect the DAC. I will check it with my oscilloscope for you some time this week.

I'm interested to know what you would do next, after identifying the DAC as the culprit. Is the DAC not receiving the digital bong signal or is it having trouble outputting it?

#31 38 days ago

No worries. Appreciate you following along. Very interested to hear what you find. Looking forward to it.
Cheers and thanks again

#32 37 days ago

I just measured the bong on the DAC channel. I probed between C15 and R22. Hope this helps you a bit further!

bong on DAC (resized).png
#33 37 days ago

Thanks. Confirms what I was thinking. Well besides the fact I need a scope!!

Some more background info...when this board came to me the tants were blown off the board at c26 and 28. 7912 was replaced along with X-1 and both tl084's plus both fuses were the wrong values.

The logic circuits test off that are connected to the power circuits [when compared to known good board] where as the input channels and sound buffers all test exactly like a known good board.

I think the original damage caused the issue I am having and must have damaged a smaller cap or component enough to not boot and bong but work fine with signals sent to it.

There are more boards out there with this condition I am sure but most will not notice as it still works fine.
Time to dig deeper.

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