Williams (Robotron) sounds missing

scottz29

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Anybody had sounds go missing on any of their Williams games before? They are not being improperly used, or duplicated, they are most definitely missing.

Shot sounds, and most other sounds are there. Explosion noise is gone. There are so many sounds going on in that game it's hard to describe the ones that are missing. Another notable sound missing is the one in-between screens where the color "tunnel" is drawn.

I am guessing stuck pins on one of the 74xx chips on the sound board?

The 2 fuses are fine.

It just happened last night and I just got a chance to look over the schematic now, haven't played around with it, thought I'd post a message to see if anybody's had this problem, and what they did to fix...

Thanks!
 
try replacing the electrolytic capacitors on the sound board first. while its out, reflow any cold solder joints there too.
inspect wires, pin spacing and connectors for any flaws or oxidation. replace if necessary.
 
Step #1, if it is the original wiring, verify continuity and push the wires down on the IDC (POS) connectors until you can replace it. The IDC connectors were never designed for 30 years of operation and the wires will work their way off the blades and you will lose connectivity.

If you are missing some sounds and other sounds are fine, you are having data cable dropout.

PM Dokert and go get a new wiring harness. You will be glad you did.

ken
 
Just a quick update, I fixed all my cold solder joints on all header pins, and verified continuity of the connector from the ROM to the sound board. No change.

I've been going thru the schematic the last couple days and I'll have time tonight to work on it. I'm going to logic probe the sound board, and when I get some more money to place a Bob Roberts order, I'll do a cap kit also. But I'm expecting either the PIA or one of the 7400/7408 logic gates to be bad at this point.
 
Double check the +5V on the sound board... remember the sound board has its own regulator on it that it uses to power its logic... if the regulator is bad... no power... no sound.
 
I have sound, just missing certain sounds. Actually, "Sound Line 3" is missing when going thru the diagnostics. (Just realized I had not posted that here initially)
 
If you are missing certain sounds, it may just be the sound ROM is fubared. If you've got an eprom burner or know someone that has one try burning a new ROM.

ken
 
Well ok, I have to eat some of my words here...:001_ssad: after playing my Robotron the last few times, it seems the sounds are not actually "missing" as I initially suspected, but many are incorrect after all. Some sounds I suppose you could say are missing, as they are never heard, but this is probably because sound line 3 is dead, and/or the sounds are being selected incorrectly.

For example, the sound when picking up a human is the sound normally used for the tank firing --- beeeeeoooowwwww sound (lol).

Anyway, I got a chance to probe the sound board tonight. Sound line 3 maps to pin 5 on the J4 connector on the sound board. I put the game in sound test mode and tested for a low pulse on pin 5. All other sound lines pulsed low on their appropriate pin. Tracing back to the ROM board, pin 5 was not pulsing on the J4 connector there either.

I had to go upstairs to feed my kid (new baby!), so I had to stop there. I didn't get a chance to look at the schematic until just now, but are those signals on the ROM board being fed by the PIA itself? I'm assuming the pin on the PIA that feeds pin 5 on the J4 connector is stuck high... Can anybody confirm my suspicion, or should I look elsewhere as well? ROM test passes fine ("All ROMs OK")
 
According to the schematic, the ROM board PIA drives the sound lines directly. So if it is dropping a signal, that probably means the PIA is bad. Although there is a pullup resistor which should probably be checked as well.

The ROM test does not test the sound ROM, just the ROMs on the ROM board, so there is no way to tell if the sound ROM is bad except to pull it and verify it in a ROM burner.

There is one other possibility, on the sound card IC5 is a 4050 buffer. It sits on the data lines. If one of the cells went bad it could affect the signal from the ROM card. Try unplugging the sound card and watch the signals on pin 5. If it never fires than it probably is the PIA if it fires when the sound card is unplugged, it may be the 4050 on the sound card.

ken
 
According to the schematic, the ROM board PIA drives the sound lines directly. So if it is dropping a signal, that probably means the PIA is bad. Although there is a pullup resistor which should probably be checked as well.

The ROM test does not test the sound ROM, just the ROMs on the ROM board, so there is no way to tell if the sound ROM is bad except to pull it and verify it in a ROM burner.

There is one other possibility, on the sound card IC5 is a 4050 buffer. It sits on the data lines. If one of the cells went bad it could affect the signal from the ROM card. Try unplugging the sound card and watch the signals on pin 5. If it never fires than it probably is the PIA if it fires when the sound card is unplugged, it may be the 4050 on the sound card.

ken

My money is on the PIA. They seem to fail more than anything else. Isn't there one on the sound board itself as well?
 
Gahhh... well I did finally get a chance to probe pin 12 on the ROM board PIA, and it was stuck high and never pulsed low when I put the sound test on line 3. I have a PIA on order from Bob. I'll make these other checks in the meantime and report back...wish I had checked Klov first...oh well.

University of Google helped me a bit with the concept of a pullup resistor, where exactly is this on the ROM board? Is that the 4.7k DIP package by any chance?

According to the schematic, the ROM board PIA drives the sound lines directly. So if it is dropping a signal, that probably means the PIA is bad. Although there is a pullup resistor which should probably be checked as well.

The ROM test does not test the sound ROM, just the ROMs on the ROM board, so there is no way to tell if the sound ROM is bad except to pull it and verify it in a ROM burner.

There is one other possibility, on the sound card IC5 is a 4050 buffer. It sits on the data lines. If one of the cells went bad it could affect the signal from the ROM card. Try unplugging the sound card and watch the signals on pin 5. If it never fires than it probably is the PIA if it fires when the sound card is unplugged, it may be the 4050 on the sound card.

ken
 
University of Google helped me a bit with the concept of a pullup resistor, where exactly is this on the ROM board? Is that the 4.7k DIP package by any chance?

IIRC it is. I don't have access to one to look at, but the Williams engineers were veryfond of the resister packs for pullups for some reason.

ken
 
Fixed. It ended up being the PIA on the ROM board...got lucky and it wasn't the 4050 buffer, which I didn't have any of. :cool:

Threw in a 40-pin socket while I was at it, of course.

Thanks to all who replied to this thread to help me out, esp. YellowDog, our resident Williams guy... Good karma will be sent your way! :D
 
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