Dead Top Gunner board

hindered

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I picked up a non working Konami Top Gunner PCB in a really stinky converted Zaxxon cabinet. Still trying to decide what to do with the cab, so in the meantime I figured I'd troubleshoot the nonworking PCB. The board shows no signs of life when powered up in a known working cab, and the monitor just shows white w/horizontal lines. The only history I have of the board is "it used to work, then I put the cab in my garage for 2 years and now it doesn't work anymore".

I cleaned the board, reseated and cleaned all the socketed chips and cleaned the edge connector. I put the PCB into my Astro City cab and got 5.15v, -5.15v and 11.96 when testing at the edge connector. Visual inspection shows no missing parts, no bulging or obviously broken caps, and no obvious cold/cracked solder joints.

Not sure where to go from here. Any ideas?
 
Anyone? I realize this isn't a popular or valuable board, but I'd like to be able to try to fix it up for the experience gained...
 
Okay, I had a High Impact Football board I was using for testing and had hooked it up into the rig I took the Top Gunner board from. It was working fine long enough for me to fine tune the monitor, get rid of the sync issues, and see that the monitor looks more or less good and is in no need of a cap kit at this time.

However, while I was futzing around with the wiring a bit, the picture cut out... One minute it was working, one minute the screen was blank I'm guessing either this rig, or something I actually did while wiggling the wiring, fried the High Impact board... I put it into a known good cab with the same results.. one LED lit (one unlit) and no signs of life... I don't have a sound board so I can't see if it'll play blind. I did test the +5v at the test point and the reading was fine.

I then hooked up a Super Dodgeball PCB and had picture again.. I hooked up the speaker and only got a hum/static noise... Put the Super Dodgeball PCB into the known working cab and the sound is working fine.. I am 99% sure the speaker I tested on the first cab was fine too, though I'll test it tomorrow to be sure. I tested the voltage coming from the power supply and got 5.01v and 11.96v, and the -5v was cut (the wiring job in this cabinet is terrible) so no issues there, unless the Super Dodgeball PCB requires -5v for sound. Anyone know if it does? EDIT: I just found the manual on crazy kong, and it appears -5v is required for sound... If -5v was missing, would you expect just a hum/hiss instead of the music/sfx? EDIT2: Ok the manual indicates that no sound can be a problem with 12v... which is fine on the original unit... I'm confused again.

I'd like to (if possible):

Repair the Top Gunner board
Repair the High Impact Football board
Determine if something is wrong with the power supply / JAMMA harness in the rig that is apparently frying boards so I can address the issue. The wiring is pretty atrocious...

Any ideas or insight?
 
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Talkin to myseeeeeelfffff talkin to myseeeeeeeeeeeelllllllllllllllllffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff
 
Hi!

Now you're not talking to yourself. :D

There isn't much in the JAMMA age worth repairing. They started using custom IC's, which are difficult or impossible to replace. The only reason most of us hobbyists can repair any circuit board is because there is heavily detailed and specific documentation freely available. Without that documentation, it will take extensive circuit troubleshooting experience to fix the undocumented boards only using schematics.

If you are wanting to learn this kind of stuff though, I have a Badlands board that blows up power supplies with your name on it for the cost of shipping! :D
 
Check the power supply for bad caps.

One way to do this is if you have a voltmeter, put it on AC and read the output from +5v to ground. it should be less than .05 volts, the lower the better.

However, that's not really a good way to check the output of a switching power supply since those output high frequency instead of the 60Hz coming off the AC mains. For that you should look at the caps inside the power supply to see if any are bulging or have ruptured.

You either have a miswired cab or a bad power supply if you are blowing boards with it.

Or, you simply have exposed wiring and you shorted out something. I've never seen a board blow from crossed wiring on inputs unless you crossed it with 12v or -5v. ;) oops.

RJ
 
Hi!

Now you're not talking to yourself. :D

There isn't much in the JAMMA age worth repairing. They started using custom IC's, which are difficult or impossible to replace. The only reason most of us hobbyists can repair any circuit board is because there is heavily detailed and specific documentation freely available. Without that documentation, it will take extensive circuit troubleshooting experience to fix the undocumented boards only using schematics.

If you are wanting to learn this kind of stuff though, I have a Badlands board that blows up power supplies with your name on it for the cost of shipping! :D

Ha thanks, I was about to go crazy from the loneliness... I'm sure the JAMMA boards aren't really worth repairing, they're probably only worth $10-20 even working... but still it would be a good experience to try to fix them maybe.. My real concern is fixing the power supply so this doesn't happen again..

channelmanic said:
Check the power supply for bad caps.

One way to do this is if you have a voltmeter, put it on AC and read the output from +5v to ground. it should be less than .05 volts, the lower the better.

However, that's not really a good way to check the output of a switching power supply since those output high frequency instead of the 60Hz coming off the AC mains. For that you should look at the caps inside the power supply to see if any are bulging or have ruptured.

You either have a miswired cab or a bad power supply if you are blowing boards with it.

Or, you simply have exposed wiring and you shorted out something. I've never seen a board blow from crossed wiring on inputs unless you crossed it with 12v or -5v. oops.

RJ

I"m leaning towards the "oops" suggestion, because the board was close to some exposed wiring.. which may have been 12v (although probably not -5v)... Still, to be safe (and since the wiring in this cab is a total abortion) I've ordered a new JAMMA harness and connectors and plan to rewire the whole thing.

Things I've tested:
Output from the wall
Output from the Power supply (5v)
Output from the isolation transformer (to the monitor)
Output from.. whatever the thing is that converts 5v to 12v, -5v and -12v

Everything seems ok so far. I'm not sure what you mean about testing from +5v to ground .. when I tested that (on the power supply itself) I got 5v.. Maybe I'm doing something wrong (perhaps you mean with the unit not plugged in)? Could you please explain in more detail?

I've attached the best pics of the power supply I have, plus pictures proving that the High Impact board worked for a while at least. :)
 

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Everything seems ok so far. I'm not sure what you mean about testing from +5v to ground .. when I tested that (on the power supply itself) I got 5v.. Maybe I'm doing something wrong (perhaps you mean with the unit not plugged in)? Could you please explain in more detail?

Oh, I just reread what you said... Not sure why testing the +5v to ground on AC settings would indicate a bad cap -- I will perform this test tonight, but could you please educate me on how this works / how this indicates a bad cap?
 
The filter caps should keep any ac ripple or noise off the line. The more the noise or ripple the more the crashing you'll get on the game.
 
The filter caps should keep any ac ripple or noise off the line. The more the noise or ripple the more the crashing you'll get on the game.

Understood. I got some low value like .014 or some such, should be good there. Back to the drawing board I guess.
 
Oh, a couple of weird things.. the monitor is a WG K4900. When I turn it on with no PCB, or when I hook up the High Impact PCB, I get the same results -- the monitor is powered, but is dim. When I hook up the Top Gunner PCB, the monitor displays a bright white screen, which will then cycle to Green, Blue, Pink (Red) etc... almost as if it's stuck in a test loop. Ideas?

Oh, and I tried the Super Dodge Ball PCB again today and was able to get sound -- however, there was still the hum/static noise along with the sound effects. I'm guessing there's something wired weirdly.. Waiting for the new JAMMA harness to arrive so I can rewire it.
 
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