QBert sound issue

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This is a new one for me!

I have a Qbert that I just picked up and has working video now!
It sounds "you turn me on" or something or other when booting, but during game play there is no sound...

Any ideas on why?

The speaker obviously works. There is static if I try turning it up through the coin door...but as stated above, clear sound for the start up.

I'm confused.
 
Chumblespluzz did a nice flowchart for Q*bert sound troubleshooting that may prove helpful:

Troubleshooting Q*bert Sound Problems

It happens to every Q*bert sooner or later - the sound dies. There are many Q*bert machines out there that need to have their sound repaired, but not many people know how to fix them. To help work through the most common problems found with Q*Bert sound I've created the flowchart below. If you run into any difficulties while repairing your Q*bert's sound, or if you have a problem that is beyond the scope of the flowchart, feel free to e-mail me at [email protected] with any questions.

Before you begin, however, there is one very important modification you should make that will greatly reduce the possibility of sound failure in the future. The original Q*bert designers decided to power the sound amplifier off a +30v line from the power supply board. Unfortunately, the amplifier chip is rated at only +27v. One of the most common Q*bert sound problems is a fried amp chip. To remedy this problem, replace D26 on the power supply board with a 24v 3-watt zener diode. This will reduce the supply voltage to about +25v, perfectly adequate for the amplifier and well within tolerances. The only other thing driven off this line is the knocker, and 24v is plenty to drive that as well.

qbert_sound_flowchart.gif
 
Great info Mike!

I think I may have found the issue...

I replaced the 2 sound ROMS (burned new ones) no go.
I replaced the 74SL377 at A10 on the main, no go.
I replaced the 6532 at U15, no go.

Leaves me to believe that It's the U16 and/or U17 on the sound pcb...

I do have a new power supply coming in from AS (the switcher one)...should take care of any future issues since it's running on 12v.
 
I put the new PS from AS in and still have the same results. Set the +5 to 5.05. Worth a shot! Runs cooler, knocker works too.
 
The fact that you get "Hello, I'm turned on!" when you start up means the audio amplification is OK and that the sound board is working.

But the sounds during the game are generated when a command is sent from the CPU board to the sound board. So check the comms between the two. Could be the harness, edge connecters, or the TTL chips that handle the comms between those PCBs.

Where does your problem fall in the flow chart?
 
That flow chart is little use in most cases.
If your hearing hello I am turned on it only means your 30v is good and the amp is working.
 
I replaced the 74LS30 at U17 and it fixed my sound problem. Me, being the dumb shit I am, soldered the new chip in rather than soldering in a socket. I have the 74LS04 for U16, but haven't yet needed to change that one out.
 
I have a weird problem too. ALL of my sounds work - however the sound Qbert and Coily make when they jump off the side is monotone instead of a falling off sound. I.e. an "ahhhhhhhhhhhhh" vs. "AAAAaaahhhhhhh..."

That's the only sound weirdness.
 
All is good. Forgot to post a resolution to this.

Replaced A10 (74ls377) on the main and soldered in a new socket for U17 and installed a 74ls30 and it works perfect.

Installed Mike's kit to test it out too! Perfection.

Thanks for all the help!
 
Yes, the one with the 3 connectors (volume) do you want to pm me on a price, also i would take whatever sound a-10 sockets etc. you recommend.
 
Let me make sure I have one left. I bought about a dozen of them a year ago and have used or sold most if not all of them. If I dont have it I will be putting in several parts orders this evening so I will look into getting them back in stock.
 
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