Rosemountain <
rosemoun...@yahoo.com> wrote in
news:d85a3b07-1c61-46de...@d10g2000vbk.googlegroups.com:
>> Er, a better way to say it is that it slices the insulation and makes
>> contact with the wire inside.
>
> Ok, so I focused on the Credit button switch and did a continuity test
> of that Green wire all the way back to the board, that test confirmed
> continuity. I then tested the Yellow wire that happens to go from the
> Credit switch to the board in one straight shot. So I did a continuity
> test of that yellow wire from the Credit switch to the board and that
> confimed good continuity. So now, I am really at a loss. Could there
> be a short somewhere else I'm missing ?
Just thinking out loud here...
* You did a continuity test across the switch itself, pushed the switch in, and
had continuity, right?
* You did a continuity test on each wire, back to the head, and found each one
continuous.
* You did a switch edge test on the CPU board itself, from the column connector
to the row connector, and that column worked in that test.
* None of the switches in that column work when it's plugged in normally.
Unless I'm missing something (which is kind of why I was 'thinking out loud' up
there), I only see two possibilities here...
1) Something is shorted (either on the playfield or in the cabinet) and sending
extra voltage into the switch matrix column line, essentially 'overriding' the
closed switch. Though I would think this would be evident by blowing a 2n3904 in
the switch matrix column, which would have been shown by failing the board-only
switch matrix test.
2) This is a WAG (wild ass guess)... I've run into it on more than one occasion
that SRC6 is damaged / cracked internally, so that the game's switch matrix's
signals become garbled almost to the point of unrecognizability. In one case, the
switch matrix was failing, then as a sanity check, I checked one of my working
games and found the same thing on *just a few* of the switch columns! I replaced
SRC6 on both boards, and the switch matrix signals cleaned up on both boards, and
the original board that was exhibiting crazy switch matrix problems was fixed.
(The one that was exhibiting no symptoms but working stayed working... :) ) It's
a WAG, but maybe your board is suffering from the same syndrome?
I don't have any *really good* ideas at this point, to be honest.
Oh wait, yes I do! We can test for #1. (We can test for #2, but you'd need an
oscilloscope, and I don't expect you have one. :) )
Turn the game on (don't care what mode), and pull off 1P8. Check for DC voltage
(with reference to ground) for each pin of 1P8. Shouldn't see much of anything.
If you do, then that line has a short to it and is backfeeding voltage into the
switch matrix.