Qbert lost all game sounds

digitalwack

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Hoping someone might be able to help. My Qbert is missing all game sounds and speech. It does say "Hello I'm turned on" while powered on. I know I must have blown something up as I was replacing the A10 chip and accidentally plugged it into the empty socket next to the battery on the logic board. Fuse was blown for the knocker and all game sounds were lost. I replaced the fuse, and the knocker works. I checked the voltage for the soundboard and was getting near 50v. Rebuilt the power supply and back around 29v, but still no game sounds. I've since replaced A10 and U17 with no luck. I have U15(6532) on order, but didn't know if anyone might have any other suggestions? Thanks
 
From KLOV-Q*Bert site:
Fixes
The game suffers from a high sound chip failure rate probably because the LM379 audio amp is rated at 28 VDC and the power supply pumps 30 VDC through it. Replace the 30 volt Zener diode on the regulator board with a 27 volt Zener, equal to or greater in wattage. This should help prolong the life of the audio amp.

If you had 50V on the 30V-rail, there is´a good chance the LM379 is in silicon heaven. ;)

U21 and U22 (LM741) is another guess.
 
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I immediately thought the LM379 as well, but assumed since the "Hello I'm turned on message" and test tone button are working my amp is good?
 
if I'm not mistaken these use PIAs just like the Williams boards. the hello I'm turned on may be equivalent to the test tone on Williams hardware in that it circumvents the PIA -- Qbert's power on sound may do the same (ie. the sound board plays that sound itself, it doesn't require any communication from the main board to trigger it)

in which case, the PIA might be bad... if there is one. I thought I saw a 6821 on an Argus board once, and that machine in particular plays wrong sounds just like a Williams game would if that part went bad.

you may even be in luck, it's probably soldered in directly!
 
if I'm not mistaken these use PIAs just like the Williams boards. the hello I'm turned on may be equivalent to the test tone on Williams hardware in that it circumvents the PIA -- Qbert's power on sound may do the same (ie. the sound board plays that sound itself, it doesn't require any communication from the main board to trigger it)

in which case, the PIA might be bad... if there is one. I thought I saw a 6821 on an Argus board once, and that machine in particular plays wrong sounds just like a Williams game would if that part went bad.

you may even be in luck, it's probably soldered in directly!

i think your thinking of the riot 6532 on that pcb. we stock NOS lm379s chips and we have the 5 watt zeners 27v also if you need.
 
The 74LS377 shouldn't care if it's plugged into A1J2 -- just a little bus contention.

If you're getting 'Im turned on', the CPU, (some of the) ROMs, SC01 and RIOT are at least mostly good... (there's no RAM on the board other than in the RIOT, and I don't think it can do the startup speech without RAM.

Most common failures I've seen are U24 and U17....

If you don't see PA7 pulsing on the RIOT, you're not going to get anything other than the startup sound.

I just fabbed some replacement gottlieb sound boards, but left off the SC01 and support circuitry to make them smaller since the chips are impossible to find now anyway :)
 
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Thanks for all the responses. I'm getting 4.99v at pin 15(PA7) of the Riot chip. How often should I see the pulse/strobe? I'm a solid 4.99v.
 
It it's stuck high, then one of S1/S2/S4/S8 is stuck low... (driven by A10 on the CPU)
Sorry, I'm pretty much a novice, What do you mean by S1/S2/S4/S8? I tried swapping out the socket at A10 and replacing the chip. Still No luck. Unless someone has any other suggestions, might be time to mail it off. Now I'm wondering if the problem is on the logic board? Any other suggestions would be greatly appreciated!
 
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