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.

Bump for day crowd

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.

Bump for evening crowd

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 .

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!

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?

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

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

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?

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?

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.

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..

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.

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.

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?

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?

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

anyone? Bueller..bueller.. lol

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

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

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.