(Topic ID: 207788)

Comet - restart the machine

By jimy_speedt

1 year ago

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  • 13 posts
  • 3 Pinsiders participating
  • Latest reply 1 year ago by jimy_speedt
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#1 1 year ago


I have fetched a Comet that apparently had not played for ages.

When switching on the machine here are the symptoms.

- playfield GI or part of the GI works
- MPU boots properly with a digit code 0
- no display working
- no sound except hum
- no reaction of the coin door button, start button, nor adding credits from the door
- Surprisingly, at machine switch on: flipper bats, switches and coils are active. If I press flipper button or I press the sling rubber coils work. And I have not started a play !!! I cannot say much more as I see nothing on the screen and there is no reaction from the diagnostic buttons.
- I have the 12vdc and 5vdc on the Power Supply board.

Also as you can see on the pic, someone in it life has added a wooden board with a PCB, and button, at about 10" from the coin door.

Anyone can help me to dig further into that ?


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#2 1 year ago

Job #1 would probably be to check if the Master Display Board has high voltage (set meter to AC).

I assume you already checked the HV fuse on the power supply.

#3 1 year ago

Ok I wlll do it,

Yes the fuses are ok


#4 1 year ago
Quoted from vid1900:

Job #1 would probably be to check if the Master Display Board has high voltage (set meter to AC).
I assume you already checked the HV fuse on the power supply.

To Clarify this, the Displays are probably out. Either outgassed, or high voltage section failure; so you are unable to see that they probably say adjustment failure, indicating that the batteries on the CPU went dead, and the machine is awaiting you to enter diagnostics to set pricing and other features.

try tapping the test/reset button on the cpu board and see it the machine doesn't at least go into attract mode (lights dancing), and then the coin switches should add credits, and the you could try to start a game.

Optionally, you can hold down the adjust select button after tapping it a couple of time, until it cycles through all the adjustments, or the dirty method of quickly flicking power off the on again to get it to boot.

If it does, then you're at fixing the battery issue, and the display issue, which are both probably expected failures for the condition of the machine when you got it.

You would at least know where you are at if you can get it to continue on past the adjust failure it probably has on the screen you can't see, if the cpu really goes to a status 0 when booting.

#5 1 year ago

That hacked rouge board looks to be some kind of timer board, there is what looks to be a 555 timer at one end, and the other board goes to a couple of relays. They were probably using this to try to get around the same battery issue at some point in the past by quickly resetting the cpu; and the switch probably reset the timer as well....

What wires is that thing spliced into?

#6 1 year ago

Thanks a lot themadman,

I ll first answer the hacked board stuff. If I am not wrong:

1. Remote press button: Wire brown/green goes to start button, wire grey goes to MPU 1J10-3 (indicated as left coin chute)
2. Left board: grey goes to power driver 3J3-8, 34v solenoids, black to 3J6-14 ground
3 right board: red goes to power driver 3J6-3, 12v, white and white/blue to coin door.

The transitor with cooler is broken on right board, I guess I should first remove that tricky thing and restore original connections.

If by chance you could help me connecting the board pins to the right cabinet component it would be great !!

Thanks again

#7 1 year ago

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#8 1 year ago

Here are the schematics so you can put the coin door back to stock.


Let me know if you need detailed pictures.

#9 1 year ago

Thanks Vid

#10 1 year ago

I read the manual, but I am unable to see

- where the start button connects to
- all the above MPU and power supply pins, if I remove them with the tricky assembly, what are the right connections

Thanks for your patience

#11 1 year ago


Happy to say that there is some progress, but do no know why.

- so, when I switch on the machine, all contact, flippers and coils are active, but there is no reaction to coin chute nor start game. And the CPU error code is 0

- if I press the diagnostic button on the CPU, miracle. The GI works and attract mode as well. No display however. I can start a game normally. Sound is ok.

Big progress, but why does the game behave normally only after I press the diagnostic switch ? Can it be a battery leakage ? Some small green traces below

Regarding the display, I do not have the high voltage, I have the 5vdc, +10 instead of +100 and the -100 vdc are close to 0. Dead resistor and I ll replace the capacitors.

Thanks again for helping further with the CPU issue

#12 1 year ago

Final chapter: the 4,5vdc battery was removed, after putting a new one. The game switches on in attract mode.

I now have +-100vdc on the display board, but 3 slave displays are outgased. Hope to find some in second hand, otherwise, I ll have to get the pinscore led kit. Which I do not want basically.

Thanks again

3 weeks later
#13 1 year ago

The pin is up and running. Thanks

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