Xenon buzz crackle fizz

ArcadeTechGW

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Bally Xenon, electronic, 1978

My Xenon is on the fritz for the first time in a long while. I had to do a tear down when I moved, and the audio has been awful.

First "shotgun" guess was bad caps on the audio boards, so I changed all those. No change.

Any suggestions on where to go from there?
 
Good question. I haven't metered them out, and should. Time to pull out the Fluke and see what I get.

Unplugged, of course. I did burnish the pins where I could - the inter-board connector looks gold plated, so I left that alone. I re-flowed the header pins while I was doing the CAP job, since that could be a place for problems. I'll probably pull the MPU and re-flow that.

Thanks. I'm trying not to further cast-about furtively on this one. I like playing the game too much, and really want to get this fixed.

Next up once I solve this is the CPR Playfield transplant (gulp!).
 
Do all the boards have screws in mounting holes and are they tight? try reseating chips in audio section, might ne a dirty/bad volume pot also.
 
Screws in mounting holes - yes. Tight - Yes.

Pull, clean and reseat chips in audio section - Good idea.
 
i have seen the tda2002 fail and do what you are experiencing.

Edit: did you replace the volume pot?
 
Last edited:
Hopefully, it's not the TDA2002.

No, I didn't replace the volume pot. I did wipe it well when the problem manifested. It starts after the game has played a few minutes, so I'm leaning towards chip legs or bad connections. Time to get out the meter.

I had remotely mounted the batteries when I snagged the game back in 1984, and just replaced them with the alkaline battery pack and a few other minor mods.
 
Hopefully, it's not the TDA2002.

No, I didn't replace the volume pot. I did wipe it well when the problem manifested. It starts after the game has played a few minutes, so I'm leaning towards chip legs or bad connections. Time to get out the meter.

I had remotely mounted the batteries when I snagged the game back in 1984, and just replaced them with the alkaline battery pack and a few other minor mods.
If you need a tda2002 I have some, you can also sub a tda2003 if that's what you have laying around.
 
Well, this has been sitting idle for too long. Time to rez up efforts to get this fixed.

Status so far:
When I push the test button on the board, the audio is clear as a bell. When playing, it's scratchy as hell.

I'm not sure the TDA 2002 will do that. I'll have to pull the diagrams, but it should be in the circuit in both cases.
 
Well, this has been sitting idle for too long. Time to rez up efforts to get this fixed.

Status so far:
When I push the test button on the board, the audio is clear as a bell. When playing, it's scratchy as hell.

I'm not sure the TDA 2002 will do that. I'll have to pull the diagrams, but it should be in the circuit in both cases.


This is going to sound weird but I know you post a lot and you'll be able to figure out what I mean here. I'm getting dinner and I'll be home in a little bit. I'll edit my post with a little more detail.

It sounds like it's on the MPU board somewhere I think there are some address lines on one of the two right connectors on the MPU check those make sure those are flowing properly and have good continuity.
 
Well, this has been sitting idle for too long. Time to rez up efforts to get this fixed.

Status so far:
When I push the test button on the board, the audio is clear as a bell. When playing, it's scratchy as hell.

I'm not sure the TDA 2002 will do that. I'll have to pull the diagrams, but it should be in the circuit in both cases.

That's an odd symptom.

But is it particular audio? I had a similar problem with an Elektra, I know,d ifferent Squawk and Talk, but in that case, the background sound and voice was perfect, but the sound effects were static. Turned out to be the LM3900 opamp chip.
 
Re-Starting troubleshooting efforts on this project.

In doing a bunch of research (including getting out my Bally F.O. 560 Troubleshooting manual (which wasn't any help)), I have found the following 4 usual "suspects"

1. The 1N4004 diodes on the Vocalizer board - these get warm. My connections looked like they were toasty, so I reflowed all of them. No change so I'm replacing them.
2. The AY-3-8910 on the Sounds Plus board - It's a 40 pin chip that generates the sounds. On order now with a new socket.
3. The MC3417L on the Vocalizer board - another thing that goes bad and silences Xenon.
4. The 7805 5 voltage regulator on the Vocalizer board.

First off will be the diodes. I have repinned the MPU connectors (replaced the MPU connectors with new). Again, the voices play when I push the test button but otherwise, Xenon is silent. The main volume control works - I can hear the amp humming, but no audio other than that.
 
When I was fixing up my Xenon last year, I too was getting a ton of "static" (for lack of a better description) in the sound. I pulled the sound board, check all the 0.156 pins and reflowed one cold solder joint, and replaced the little red test button fixture (the front and button of which were broken off) with one harvested from a junk MPU. That fixed my static problems entirely.
 
When I was fixing up my Xenon last year, I too was getting a ton of "static" (for lack of a better description) in the sound. I pulled the sound board, check all the 0.156 pins and reflowed one cold solder joint, and replaced the little red test button fixture (the front and button of which were broken off) with one harvested from a junk MPU. That fixed my static problems entirely.
It isn't static, it's SILENCE.

And remember, Silence is Golden. Duct Tape is Silver!
 
Parts in flight. Waiting for multiple shipments. Drumming fingers - want to get this done so I can get the motivation to start the playfield change.

The CPR playfield and new plastics are waiting - for too long.
 
Ugh.

I'm still waiting, for the parts I need, to come into my life.
Still waiting, for the parts I need, to come into my life.
I'm still waiting, for the parts I need to make my game come to life.
Yeah waiting, for the parts I need, for Xenon to survive........
 
3 of the 4 crimpers are in.

None of the parts. Go figure.

Dang, I want to get this thing fixed and working.
 
The diodes arrived as well as the AY-3-8910 chip from Marco.

But if I can hear the sounds, do I need the AY-3-8910 chip?

I removed the old diodes, but they tested fine so I'm waiting for the 7805 and the MC3417L. My plan is to replace the MC3417L first after testing the 7805 and then replace the 7805 if my 5 volts doesn't look good on the audio board, then try it out and see what I get.

No sound - unsolder, install a quality double wipe socket and install the AY-3-8910 Chip.
 
The diodes are replaced and I stood them off the board around 1/2 inch to keep them from browning the board. All the traces lifted from the heat damage in that corner. No change in performance, but then I didn't expect any since the other diodes tested good. I replaced them due to the noted heat damage in that corner of the PCB.

I'm waiting for the MC3417L right now. Maybe today?
 
The MC3417L just arrived. Now to grab a socket and fix it after work and dinner. Keeping my fingers crossed!
 
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