Tempest. Got video but no sound.

7146aaron

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I got this tempest the other day. It was mostly dead. After some work on the monitor, and board I got video and can play a game. The beam current is a little high. I just ordered q900-904 to limt the beam current to where it should be. That should take care of that.

Anways. Back to the sound. No sound at all. I turn up the volumn pot and there is an audible hum. I have already verified voltages on the Ar. Where do I go next. I have never had a problem with Tempest sound before so.... kinda at a loss.
 
there are 2 separate audio amplifiers so if only one was bad, you would have low sound instead of no sound,i can tell you that much. Did you ohm out the speaker ?
 
Tempest.

there are 2 separate audio amplifiers so if only one was bad, you would have low sound instead of no sound,i can tell you that much. Did you ohm out the speaker ?

Looked at this a little more since I posted.

I have ohmed the speaker from the cab connector by the interlock switch. It is fine.

I ohmed all the wires from the game board to the solderpads on the AR. Went ahead and reflowed everything on the ar and checked for corosion in the sockets. Also I ohmed the wires that go from the AR through the volumn pot and so forth. Basicaly all the wires that send the sound signal or return it. All fine.

I went ahead and pulled the boards and reflowed the headders on the interconnect cable. Also while I was there, I ohmed them too. I reaseated all the socketed chips. The board is very clean. There was no corosion or even black tarnish on any of the chip legs or sockets.

I tried out test mode. It comes up fine but without being able to hear the tones. It is not much help.

I was looking at a schem and there is two custom chips for the sound i/o. I think it is unlikely for both of them to be bad so I am trying to find the common between the two.
 
Tempest

Swap in a known good A/R II and test the sound again. If it doesn't work, it is most likely a board issue.

I put in a known working AR. No change. I put in a known working board set. The sound worked fine. I guess I am off to learn about that. I think I might have some extra Pokeys. Trying them next.
 
sound

sounds like pokeys to me. Had that a few times.
 
Fixed

I replaced the Pokeys with 2 known good ones. No change.

I ran down all the traces, resistors, capacitors in the sound circuit from the Pokeys to the edge connector. Everything was fine. The common thread between the 2 seperate sound signals is a LM324N quad amp chip at K6 on the auxilary board. Both sound signals go through this IC. I replaced that and the sound works great.
 
I replaced the Pokeys with 2 known good ones. No change.

I ran down all the traces, resistors, capacitors in the sound circuit from the Pokeys to the edge connector. Everything was fine. The common thread between the 2 seperate sound signals is a LM324N quad amp chip at K6 on the auxilary board. Both sound signals go through this IC. I replaced that and the sound works great.

I just want to give an update that I had two AUX boards with no sound and good Pokeys. After reading this thread and changing out K6 on both boards the new LM324Ns fixed both of em'!!

Thanx Aaron for the info! :D
 
I replaced the Pokeys with 2 known good ones. No change.

I ran down all the traces, resistors, capacitors in the sound circuit from the Pokeys to the edge connector. Everything was fine. The common thread between the 2 seperate sound signals is a LM324N quad amp chip at K6 on the auxilary board. Both sound signals go through this IC. I replaced that and the sound works great.

Thanks for the tip! I had the same problem (no sound) and it ended up being the LM324N as well.
 
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