Bally Display Issue Bally MPU AS-2518-35

dieseldogpi

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Mr & Mrs. Pacman. One of the five displays does not work at all, there is a slight glow though. Then I tried swapping plugs and that display then worked. So the question is, where would I begin to look to see why one of the displays are not working, when it isn't an issue with the display itself? Thanks...this game is so annoying.

As a nice little side note, I need to get a new coil or something for the lane change gate as it started to smell like it was one fire today...YAY!
 
You probably have a cracked soldier joint on one of the header pins on that display. Very common. Reflow all the pins on all the displays to avoid future problems.
 
Nah, if I swap positions of the displays they work. It has to be a main board issue I'm guessing. Any ideas.

Connectors. You will get really good at replacing the tiny Molex connectors. What a pain in the ass those are & there are LOTS of them. Ed @ GPE sells some really nice crimpers that make the job somewhat easier.
 
Pinscore displays. No need for High voltage.. You can disable the HV section on the solenoid driver board. and they look good...
PS-2518-211299106837_thumb_medium400_240.jpg
 
Nah, if I swap positions of the displays they work. It has to be a main board issue I'm guessing. Any ideas.

If you swapped wires to get the "nonworking" display going did you also swap the wires that were originally on that display to a known working display glass? It sounds like you've ruled out the display as the issue, now check the wiring.
 
Mr & Mrs. Pacman. One of the five displays does not work at all, there is a slight glow though. Then I tried swapping plugs and that display then worked. So the question is, where would I begin to look to see why one of the displays are not working, when it isn't an issue with the display itself? Thanks...this game is so annoying.

As a nice little side note, I need to get a new coil or something for the lane change gate as it started to smell like it was one fire today...YAY!

Check the voltages at the display first. Then check continuity of the display data, latch strobe, and blanking signals back to the MPU. Might as well check the digit enables too though something effecting the whole display is more likely caused by missing voltages or something common to all digits. Most of that will be common to all displays but I would check right back to the MPU.

If the display works in another position then something has to be funky with either the voltages or signals going to that display. Probably a wire disconnected somewhere or something like that. Could also be a bad PIA or socket. When checking continuity of the signals I would check right to the PIA pin on the MPU. Not just to the header.

EDIT: Could also be a connector problem at the MPU. That actually seems like the more likely cause. Bad connection on the display latch signal for that display at the MPU. I would still check as suggested above.

Could also be a connector problem at the display but this seems less likely. You could check continuity through the pins to the female connector pretty quickly just to be sure.

You could also check most of this stuff with a logic probe and the game in attract mode. That will probably be faster but be careful to not connect your probe to the 190VDC ;)
 
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Pinscore displays. No need for High voltage.. You can disable the HV section on the solenoid driver board. and they look good...
PS-2518-211299106837_thumb_medium400_240.jpg

He's going to be REALLY disappointed when he buys those and still has one display that doesn't work ;)

Good suggestion otherwise. Great product.
 
Check the voltages at the display first. Then check continuity of the display data, latch strobe, and blanking signals back to the MPU. Might as well check the digit enables too though something effecting the whole display is more likely caused by missing voltages or something common to all digits. Most of that will be common to all displays but I would check right back to the MPU.

If the display works in another position then something has to be funky with either the voltages or signals going to that display. Probably a wire disconnected somewhere or something like that. Could also be a bad PIA or socket. When checking continuity of the signals I would check right to the PIA pin on the MPU. Not just to the header.

EDIT: Could also be a connector problem at the MPU. That actually seems like the more likely cause. Bad connection on the display latch signal for that display at the MPU. I would still check as suggested above.

Could also be a connector problem at the display but this seems less likely. You could check continuity through the pins to the female connector pretty quickly just to be sure.

You could also check most of this stuff with a logic probe and the game in attract mode. That will probably be faster but be careful to not connect your probe to the 190VDC ;)

The voltages are fine, I checked those. As far as checking the continuity, I will check the continuity from the PIA to the displays. What am i checking with the logic probe though, I always get lost when it is logic probe time.
 
this happened to me, so i'll put it out there. i had a display that would not show one digit. swap to another position, and it was ok. swap a good one to the " bad" position, and no digit. i re-pinned, checked, all the good stuff. well, somebody , for some reason, moved a wire over one spot in the connector to the display. it was a credit display, not every position is filled. i think even on the score displays, there are open spots in the connectors.
 
...And another update. I traced the wires from the MPU to figure out which display was what. I must have repositioned something in one of the connectors or something because all the displays work. I dont think the way the displays are hooked up would make difference correct? Either way...I'm not gonna mess with the wires now, there is still ghosting issues so I am going to replace the 4543 IC decoders and hope that helps. I'll post back for the sake of mankind.
 
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