Qbert Sound Board Problem

Robotron Jon

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I have a problem with my Qbert sound board.

The start up "Hello I'm Turned on" is not heard at power up, nor is the incoherent speech of Qbert when he dies, or when Coily falls off the board. When the master game sound pot is really cranked up I think I can faintly hear something when Coily falls off the board.

The power supply has been completely rebuilt. The all the caps on the sound board were replaced. I re-seated chips. The test beep works.

I've read through other postings on this, and it seems like this is most likely U13 (74LS05), but also possibly U12(7407) and U9 (74LS75).

Where can I find these chips and does anyone have any other advice? Since I seem to be faintly hearing something when Coily falls off should I attempt to adjust some of the pots on the sound board? I'm not sure what they are for, although I believe one of them balances out the speech and the other game sounds.

In addition, this issue happened when my power supply failed.

Thanks.
 
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If your hearing the test tone when the button is pressed thats a good sign, means your amp is good. The first thing you should try is replacing the 74LS377 on the main board @ A10. It is very common for this to fail.
 
I can send you one chip, thats not a problem. Just send me a pm and let me know what you need. I can send it PP in a bubble mailer for cheap or priority flat rate, whatever you like.
 
Got the chip today - I PM'd Riptor about this a few days ago. Thanks for getting this to me so quickly. Putting it in the game now....we'll see what happens...
 
Speech is still out.

Anyone have any ideas about what to replace next? U13 (74LS05), U12(7407) and U9 (74LS75)?
 
Do you have a logic probe to check the chips? Those ones you listed are the ones I'd definitely check. I'm also fighting the same problem with my Q*Bert, but I hope to have it narrowed down to the DAC or even a bad speech chip.
 
I replaced the speech chip.

Speech still out.

Anyone have any ideas what to try next?

I have a multi-meter but I have no idea what to test for in the other chips that may be an issue.
 
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