Scored a Tron today; audio issues

TCinTEXAS

Well-known member

Donor 2016
Joined
May 19, 2016
Messages
1,229
Reaction score
66
Location
Bella Vista, Arkansas
Good news: I scored a Tron today.

Bad news: it has an audio issues. The game plays sound effects but no music. Any ideas?
 
after you do the testing it should show you if there is a problem in the sound amp and you may have one or both amp chips bad or caps. look at the connectors and headers too they can have issues.

if that isn't the issue the first thing i would look at is the power supply pcb as i recall the 3 pin connector runs that and that board and usually has acid damage and also correction i have found on alot of the lower connectors on the power supply.
 
I guess I need to RTFM, because I can't figure out how to get it into test mode. I switched the switch into test position. Even tried power it on in the test position. Nada.

I reseated connectors, wiggled wires, etc. While wiggling wires on the input side of the sound amp (I presume it's the amp; board about 5x5 directly above the PCB stack) sound came on for a fleeting moment, then went away. I couldn't get it to come back. Tested power on the input side; 11.36 volts.

I did notice this that the purple wire on one of the power supply board connectors was cut. Any ideas? Is that for some ram mod, or something, or do I need to reconnect it?

attachment.php
 

Attachments

  • cut wire.JPG
    cut wire.JPG
    92.2 KB · Views: 201
RE: Purple wire. After some research, it looks like the purple wire is typically cut by operators to eliminate some bypass circuit which apparently causes more problems than it fixes.

I guess that's not my problem.

RE: Ribbon Cable

One of the ribbon cables is separating. I don't know if that's "the" problem, but I ordered a replacement set.

I've downloaded the manual and see that there is a procedure for getting it into test mode. I'll try again shortly.
 
I guess I need to RTFM, because I can't figure out how to get it into test mode. I switched the switch into test position. Even tried power it on in the test position. Nada.

I reseated connectors, wiggled wires, etc. While wiggling wires on the input side of the sound amp (I presume it's the amp; board about 5x5 directly above the PCB stack) sound came on for a fleeting moment, then went away. I couldn't get it to come back. Tested power on the input side; 11.36 volts.

I did notice this that the purple wire on one of the power supply board connectors was cut. Any ideas? Is that for some ram mod, or something, or do I need to reconnect it?

attachment.php


those two 15pin connectors are on top of the power supply and the 3pin that runs the sound is on the very bottom of that pcb.

Yes the 5x5 board mounted on the wall of the cabinet is the sound amp.
 
After playing with the test switch, I finally got into test mode. Did a channel test, and all I get is pops on most of the sounds.

I get a faint proper sound on "Disc" and "Timer." Nothing but pops on the others.
 
Is there any way to test the sound output from the PCB, before the amp? I alligator clipped leads to iPhone headphones and probed the input connector, but just got a very faint, high-pitch whine.

Either I'm not getting anything from the PCB, or my testing method is flawed.
 
depending on what you care to do. (or have experience with)

I would pull that audio amp board (little 5x5 board as you referred to it)

reflow the solder to the header pins

If you have any capacitors, change the 3 caps that are on there (3 I think, can't remember)
with some standard caps if you don't have the axial leads. see what happens.

I would also remove the cable that connects the audio amp to the pcb stack and test for continuity between all the wires. Maybe one of the wires has a bad connector at this point.

(just a couple of ideas that you can do in the meantime while you wait for parts to get shipped).
 
depending on what you care to do. (or have experience with)

I would pull that audio amp board (little 5x5 board as you referred to it)

reflow the solder to the header pins

If you have any capacitors, change the 3 caps that are on there (3 I think, can't remember)
with some standard caps if you don't have the axial leads. see what happens.

I would also remove the cable that connects the audio amp to the pcb stack and test for continuity between all the wires. Maybe one of the wires has a bad connector at this point.

(just a couple of ideas that you can do in the meantime while you wait for parts to get shipped).


Yes that is 3 axial caps and i have that cap kit for the board and the sound amps in stock if you need.
 
you should be able to supply line level stereo audio to the amplifier board but start with the volume level low, you wont have front panel control.

Music is mixed into the game sounds on the SSIO board. If you are missing music but have game sounds I'd start by reseating the 8910's on the SSIO board. Might be the Z80 as will but probably not since you get normal game audio.
 
you should be able to supply line level stereo audio to the amplifier board but start with the volume level low, you wont have front panel control.

Music is mixed into the game sounds on the SSIO board. If you are missing music but have game sounds I'd start by reseating the 8910's on the SSIO board. Might be the Z80 as will but probably not since you get normal game audio.

Thanks. I cut up an audio cable I can plug into my iPhone. I'll test it tomorrow.
 
Still testing.

Odd... I applied an external 12v to the sound board, and output from my iPhone, and got nothing; not even a pop or crackle. I have to assume my testing method is flawed, because the game creates output, if not distorted.

I'm fairly certain, but not convinced, that the amp is bad.

I pulled the PCB stack, cleaned the dust bunnies and packing peanuts which were still stuck between the boards, cleaned the pin connectors (didn't reflow anything yet, had to get to work), reseated the 3 roms on the SSIO, reinstalled and same results.

My reasoning that it's not the sound amp (or not ONLY the sound amp), is because I get two sounds fairly clearly; the rest are just pops.

Also, I'm getting 4.6v at the board (testing at either pole of the capacitor located at the top right of the SSIO; don't remember the number, but it was a recommended test point in one of the many videos I watched). I'm assuming that's a little low. I haven't checked it at the power supply, or tried to adjust anything, because I ran out of time.

Any input is appreciated. I'll be out of town at a bike rally in Arkansas for a week, so I'll revisit this when I get back.

Thanks in advance.
 
Ok. I'm apparently dancing with myself here, but I'll update anyway.

I'm stupid. I pulled and printed a pinout on the input connector/header for the amp, but it apparently wasn't the right one. Not sure how that happened. I knew something didn't look right.

Here's the deal: There's nothing wrong with the amp. I hooked it up to 12v CORRECTLY, and is plays from my iPhone loud and clear.

Here's the rub: I'm getting 16.3v on what should be the 12v feed to the amp.

I'm late for work. Gotta go! Seriously, your input would be appreciated.
 
I'm pretty sure that the +12 supplied to the audio amp is unregulated. While +16 is high its not catastrophic.

4.6 is kinda low but it may have something to do with bad connections in between the CPU and the SSIO board. Those ribbon cables provide that voltage to the SSIO from the CPU. However, the fact that youre not getting the "Interface Sound Board Error" on bootup tells me that the logic side of the SSIO is working.

It could be a simple issue like a bad 8910 (those two 40 pin IC's sitting next to eachother) or a bad 3900, bad 4016's. Lots to things to look at.

Clay Cowgill created a test ROM for the SSIO board. It could help you narrow down "where" you are losing sound on that board.
 
I'm pretty sure that the +12 supplied to the audio amp is unregulated. While +16 is high its not catastrophic.

Well, hell. Thought I'd discovered something. At least I know the amp is good. When I get back in town, I'll make a connector to supply PCB audio signal with external 12v just to be sure.

By that time, my new ribbon cables should be in, and I can either solve my problem or rule that out. One of the ribbon cables is crushed a bit on one side, and the layers have separated. No telling what's going on in there.
 
It could be a simple issue like a bad 8910 (those two 40 pin IC's sitting next to eachother) or a bad 3900, bad 4016's. Lots to things to look at.

I see that the 8910s are "programmable" sound generators. Does that mean that I can't just pop one in off the shelf? Does it need programming specific to the game to work?
 
you should be able to supply line level stereo audio to the amplifier board but start with the volume level low, you wont have front panel control.

Music is mixed into the game sounds on the SSIO board. If you are missing music but have game sounds I'd start by reseating the 8910's on the SSIO board. Might be the Z80 as will but probably not since you get normal game audio.

I missed this response. I pulled the board and reseated the ROMs and the Z80, but not the 8910s. I'll try to do that tonight, but probably won't have time.

How geeky is it that you find yourself wanting to stay home and work on your new arcade game, rather than go to a biker rally? Geez!
 
Ok. Here's where we are on this:

I reseated the 8910s, the IC at CP39 and D12. I replaced the ribbon cables. I swapped the Z80 for a known good processor. No joy.

Checked voltage again at the silver caps. I'm getting 5.05v.

What's confusing to me is I'm getting two good sounds: the Disc Throw and Timer Warning. All other sounds are just a pop or click. With my little (and I mean very little) understanding of how these boards work, that would seem like a ROM or RAM issue; either the sound is corrupt in the ROM, or being moved to corrupt RAM when the game is running.

EDIT: After typing this, it occurred to me that it could be bad 8910s, since I believe they are sound generators (similar to a midi device, maybe?). I'll try swapping their positions to see if different sounds work. I'm not sure if that's a valid test of any sort, but it can't hurt.

Does that make any sense at all?

Thoughts? I think I'm at the point where I need professional help (wife has said that for years). Does anyone have a recommendation for repair of a Tron SSIO/PCB? I found El Dorado Games on the interwebs, but know nothing about them.

Thanks.
 
Last edited:
Back
Top Bottom