Sinistar Start Button Quit Working

WarLordAG

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Randomly the other night the Sinistar start button quit working.
I traced the wires all the way back to where they hit which I'm assuming is the interface board. Bottom right PCB.

Re-flowed solder on the header pins. Nothing.

I removed the harness from the PCB and tried directly jumping the ground pin to the player one start, no go. Jump player two start to ground just fine.

Thoughts?
 
Randomly the other night the Sinistar start button quit working.
I traced the wires all the way back to where they hit which I'm assuming is the interface board. Bottom right PCB.

Re-flowed solder on the header pins. Nothing.

I removed the harness from the PCB and tried directly jumping the ground pin to the player one start, no go. Jump player two start to ground just fine.

Thoughts?

If you go into self test, does it work reliably?

You may also want to clean the leaf switch.
 
I'm not even factoring the button into the equation as it isn't working when going directly to the input PCB.
 
I'm not even factoring the button into the equation as it isn't working when going directly to the input PCB.

If you have a logic probe, check out pin 7 and 6 of IC6. If that checks out, it could be the 6821 (IC2).

You could also check the pull up resistors at SR1 (Pin 4)
 
Hmm, I have a Defender board doing something similar.

Only half the control panel buttons work. I traced everything down
to the input board and swapped in a known good board but still no
good.

I have my spare boards in the machine right now but I'd like to
get this resolved on the bad set.

JD
 
It's been a while however from what I recall, the start switch is read by the ROM board and not the interface board. If you installed a switcher, you must add a separate ground wire from the coin door to the power supply. Use a business card to clean the contacts on the control panel switches, no sandpaper or rough materials needed.

For control problems, the interboard cable can be problematic. The PIA does fail occasionally however most problems are mechanical.

Kirk S.
 
It already had a switcher when I obtained it.

It worked fine and then quit randomly after working most of the night. It's now the switch or wiring as I said since it doesn't work going straight to jumping the pins on the PCB.
 
It's likely the main large PCB needs repaired at this point correct?

I have a buddy with a Sinistar, I suppose I could try my pcbs in his cabinet next.
 
I would suspect the IO board before the main board. I would start by swapping that one with your friends since that would be the easiest one to do.

You should also verify all your voltages are correct, try re-seating all your cables as well.
 
This has been fixed thanks to YellowDog!

Happens all the time. There are usually 3 causes.
1) bad ground. You have eliminated this by testing in a second machine/.

2) There are a couple of CMOS inverter chips between the switches and the PIA chip. These go out all the time. If you have a logic probe, look at page 7 of the schematics (you can download a PDF of the schematics from arcarc.xmission .com if you don't have them). IC6, which is a CMOS 4049 inverter chip, pulls the signal for the Player 1 start in on pin 7 and out on pin 6. Logic probe on pin 7 and press the playe 1 start. You should see it toggle. Move the probe to pin 6, if IC6 is bad, it won't toggle. Socket and replace IC6 if it does not toggle. If it does toggle put the logic probe on IC2 (the PIA chip) pin 14. If you are still seeing it toggle when you press the player 1 button, it is most likely the PIA chip (see #3)

3) The PIA chip is the big (40 pin, IIRC) chip in the IO board. If you have checked that the signal for player 1 is toggling all the way to pin 14 of this chip, socket and replace it.

Normally it is the CMOS inverter chips that go out, but the PIA can go as well. The steps above should help you isolate which one it is.

I replaced IC6 this afternoon and player 1 start is working 100% again.
 
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It's been a while however from what I recall, the start switch is read by the ROM board and not the interface board. If you installed a switcher, you must add a separate ground wire from the coin door to the power supply. Use a business card to clean the contacts on the control panel switches, no sandpaper or rough materials needed.

For control problems, the interboard cable can be problematic. The PIA does fail occasionally however most problems are mechanical.

Kirk S.

Just wanted to correct this, the player 1 and player 2 buttons are read through the I/O boards.

The coin door switches (right , left and center if available), the HS Reset, Up/Down and Advance buttons and the slam switch are read through the ROM card PIA.

Kirk is correct that if you do install a switcher, a ground wire is needed to run the switches. With Williams games, the logic is set to pull the signal low to trigger the event, so no ground, no event.

Also, with leaf switches, never, never, never use sandpaper, no matter how fine, on the contacts. You will remove the gold plating on them and they will begin to pit almost immediately. And given the lack of leaf switch manufacturers, you will regret it. Index cards or white business cards work great. For stubborn deposits, the premoistened eyeglass cleaners from Walmart work great. They use an alcohol based solution that will cut right through the worst caked on cigarette sludge from bar housed machines.

ken

BTW, I just pointed Warlord in the right direction. He did all the work. Congrats on getting your baby running again.
 
Thanks again. Wish you had been paying attention when I started the thread, or I should have skipped the thread and messages you.

Maybe someone will search and find this one day though. That's why I always try to follow up on these things when I post them.
 
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