Joker Poker 4-digit display stopped working

Zogbert

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Donor 2012
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Falcon Beach, Manitoba, Canada
Good day, all.

I replaced the drop targets and pop bumpers on my Joker Poker a few
days ago. While I was at it, I added some Cointaker LEDs behind the
backglass, including some nifty 455 flashers in behind the "Joker
Poker" title.

A while afterwards, I noticed the 4-digit display (credits/ball in
play) display wasn't working at all. Since I did the ground mods,
disabled the slam switches, replaced the battery with isolated ones
and set it up for free play, this machine has worked flawlessly.

I cleaned the fingers on all the connectors when I did the ground
mods. I just gave them a quick cleaning again on the display, and on
the A1-J2 and A1-J3. Still nothing on the 4-digit display.

After doing some reading on here, I thought it might be a power supply
issue. I checked the voltages on the power supply. The 12, 5, 4 and 8
volt ones are fine. The 60 reads 38 and the 42 reads 20. Is that
normal?? The voltage is also getting to the display, so I don't
believe it is a connector issue. I see there is a trim pot on the
power supply...can I adjust on this? Should I?

Any ideas? The four 6-digit displays are fine, and the game still
plays like a champ.

Is it safe to play the game without this display on? Will it damage
any of the boards?

Thanks so much for any and all advice.
Zog
 
Grabbed this snippet from Clay's Sys 1 repair guide:

The credit/status display uses 42 volts for it's main power, and 4 volts as its "reference" voltage. This is all supplied by the power supply connector J3, so check the voltages there using J3 pin 5 as ground.


Hopefully you had the game off when removing and re-connecting the display harnesses. Doing so with the game on will do bad things to your displays and/or cpu board :(
 
my guess might be either bad U6 or chip on display or bad pin on connector. stock board I assume or is it Ni wumpf?
 
Success! It wasn't any of the connectors. I was doing a continuity test on every wire that went to the display. Traced one to the transformer...no issues with it, but bumped against a wire beneath it, and it felt loose. I re-soldered it, flipped the machine on, and voila! One working ball in play / credit display!!
 
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