Tron Sound goes out and/or freezes, cause in the PCB somewhere...

keithsarcade

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Tron Sound goes out and/or freezes, cause in the PCB somewhere...

Just bought a Tron and was informed by the seller that he had a few issues in the past with the sound going out. Game is working all the way otherwise, so I'm thinking worst case scenario is a bad amp.

Well I am finding that the issue is there most every time. The sound will work fine, sometimes for a few minutes, sometimes for an hour or so, but eventually goes out. If the game is making any sounds when it happens, the sound will freeze (make a solid tone until you reset the game or turn it off). Either way, video still works as normal, game can still be played with no sound or a frozen sound tone. Also, when this happens, the LED on the PCB will light up. I can reset the PCB or simply turn the game off and back on, and the sound will come back, but will eventually go out again.

I havent gone into too many diagnostics with the cab, but since I have a working Satan's Hollow, I decided to try the boardset in that cab and see if the problem followed the PCB, and sure enough it did. So now I'm very confident the problem lies somewhere in the boardset, damn. This thing is working great otherwise.

Any ideas? I have reseated every chip with no luck. Ribbon cables appear to be fairly new.

Looking for diagnostic advice or recommendations on where I can send this boardset for repair.

Thanks in advance.
 
Did you try swapping all the socketed chips with the SH board with the exception of the SH ROMS? If you give up on trying to fix it CDJUMP repairs MCR boards. He fixed 4 Video Gens for me already.
 
Check this out, I'm hoping I found the culprit. That (diode?) I have circled is broken. Just found that today while I was putting new fuse blocks in the game.

OK so what is it, and is it the likely culprit? And does Radio Shack have it? If so, a quick run might get the sound working 100%. Anyone know?
 

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thats a ceramic cap on the ssio. you can completely unplug the ssio and the game will still boot, so i seriously doubt that's the problem.
 
Well that sucks. I may be sending this your way in the future. Might try to find a cheap MCR boardset first, well see. I have 2 MCR games now so a spare boardset could come in handy.
 
.01 Uf 50v axial ceramic. Doesn't have to be axial. any .01 Uf 50v ceramic will work.
 
One of those boards is the sound board isnt it, I would check that board, I have a sound issue on a Kickman, but its just a rediculous hum when the game is in attract, I was told earlier to inspect the sound gen board, so maybe thats your ticket....
 
if i were to guess - and its just a guess, my guess would be a weak socket, or chip legs that were spread out. If the sound goes completely out, and the led comes on, i'd first look at the z80 and socket. Midway used single wipe sockets that only contact on the inside of the chip legs. If the chip legs are bent outwards even the slightest little bit, they won't make good connection, and will stop making contact when the pcb gets up to temp. I've also seen a bad z80 do the same thing - work for a bit until it warms up, then quit once it gets hot. Its possible that its a bad ribbon cable, or solder joint on the ribbon cable headers, or a weak socket on any of the roms as well.
As far as the hum in attract mode - that could be a number of issues, but i'd start looking at the 6 74ls191's and the 7407 in the circuit, as well as R235 (i think, going from memory) that controls the mute in attract mode. Could also be a faulty 8910 i think, or possibly a bad cap somewhere.
 
lots of ideas - nothing for sure though. What's the voltage at the ssio? Is it low?
Again, weak/bad sockets, or the ram, or the z80, or even a bad rom, or possibly bad interconnect cables, or broken solder joints on the interconnect headers.
 
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