Have you done a switch test to see what switch(es) are being activated?
(Topic ID: 206320)
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Quoted from Sonora70:Not sure the switch test would tell me anything?
It would tell you if a switch is closed when it shouldn't be.
After eliminating any potential physical issues with switches, then you would proceed to test for switch matrix issues.
Quoted from CactusJack:That makes me think you have a switch strobe (output) either shorted to ground or stuck low (bad IC).
Check start button blades and coin switches (especially the coin lock out wiskers).
If you have done the slam switch mod on the MPU, You can start a game and then unplug the edge connector that goes to the cabinet switches and see if the playfield behaves normally.
Additionally, check the strips of diodes in the cabinet and on the underside of the playfield. Those are part of the switch matrix, and if one of those is shorted, then you will get odd behavior. Note that you can't replace those with 1N4004 or 1N4148 diodes, unfortunately--you'll have to use a 1N270 or CDSH-270 germanium diodes.
http://pinwiki.com/wiki/index.php?title=Gottlieb_System_1#Switch_Matrix
Quoted from ckcsm:I found plenty of choices on Ebay, I just ordered some for my Joker Poker
ebay.com link » Bkc International 3658amo302701 1n270 Germanium Glass Diodes Lot 100
I don't think I'd ever use that many. Out of all the sys1 games I've worked on, I've probably used less than 10 of those diodes.
Quoted from Sonora70:I'll take a look at the switches on the coin door tomorrow and plug in a new 7404 chip as well.
I just replaced it, but maybe faulty? Glad I put sockets on the board.
Do you have a chip tester? That takes out some of the guesswork when it comes to 7400 series chips.
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