Checking switches: Question about "how"...

alejandromad

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Checking switches: Question about "how"...

I have a switch problem on a Mr & Mrs Pac-Man... the right outhole.

It doesn't fail on the switch test ... even when I press it myself.
It appears to me completely dead.

I have tried cleaning the switch contacts (using a business card) but that made no difference.

Specifically, I was wondering about the testing instructions at http://www.pinrepair.com/bally/index3.htm#smatrix
... under the section titled "Testing the MPU Switch Matrix."

Step one says: "With the game off, turn OFF all MPU board DIP switches."

This pin has the Ultimate MPU PCB and I just want to be sure the DIP switches referenced above are the ones on the right side of the PCB... I guess they set game options... as opposed to the DIP switches for setting the actual game.

Yes, No?

Any other advice on testing a defective switch?

Thanks!
 
If you only have 1 switch that does not work, it likely will NOT be a column or row problem.

Check the diode on the switch.
 
I disconnected the diode on one side and tested with the diode setting on the multimeter. One way I got a reading of .51 and the other way read 0.
That seems good to me. If not, please correct me.

If so... what would be the next steps to troubleshoot a single switch failure?

Is it possible that it's something on the MPU?

-Allen
 
From my experience, sometimes switches need time to "warm up"... this is a sign that they were bad from the start, or are dying now. I had one in my Who Dunnit that worked in the test menu, and confused the hell out of me. But, when I had the game off a few days and played, it didn't recognize that switch for a few games (or it would, but only 50/50). Try replacing the switch all together and see what happens. Diode and all.
 
Look at your pinballs manual for the switch matrix. If a switch on the same column as teh problem switch works, then the column driver is probably OK.

If a swich works on the same row as the problem switch, then row&colomn is likely just fine. Check for continuity at the swich when closed., continuity of the col/row from switch to MPU.

There is not much to it.

If the swich is seems to work after a couple of actuations, just replace the switch. they are cheap!
 
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