(Topic ID: 81559)

Mr/Mrs Pacman Maze Light Issue

By pintopkp

5 years ago

Topic Stats

  • 18 posts
  • 4 Pinsiders participating
  • Latest reply 5 months ago by crazi
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#1 5 years ago

Been tracking down a number of little problems and think I have this one figured out, but need a little push in the right direction. The top four or five lights on the pacmaze flicker when yellow. Switched out the MPU to an Alltek and the flickering stopped. Put the original MPU back in, flickering came back. My question is, where should I be looking on the board for the cause of this issue? I have already repinned connectors and replaced all header pins. Thanks.

#3 5 years ago

Yes and yes. Dips are the same (transferred MPU dip settings to the Alltek) and the yellow lights do flicker in the lamp test using MPU. They do not flicker in lamp test with the Alltek.

#5 5 years ago

Ok thanks. I'll try that tonight and report back.

#6 5 years ago

Switched PIA's, problem still the same. Bad socket(s) or is there something else I should look at?

#9 5 years ago
Quoted from Superchicken:

I am a big fan of replacing those leaf sockets with machined pin. So maybe, depending on your desoldering skills and equipment. You can dig a deeper hole fast if you get too much heat or not enough heat on the pads. Great soldering tutorials here:
I would start with the basics first:
Swap in new blubs
Check the switched illumination voltage on the MPU
Recheck your work
After that it could be failing resistors or capacitors feeding the lamp board. Checking the caps can be done with a DMD. Look for one that is different from the others of the same value. I think this game also an aux. lamp board too.

I'm comfortable and good at soldering. I've resocketed boards before. I have tested known good working bulbs, swapped known good working lamp sockets and I believe all my MPU voltages were good but I will check again.

#10 5 years ago
Quoted from viperrwk:

Is it the top four or five lights? The yellow lights are controlled by the lamp driver (whereas the reds are the aux lamp driver) and all five touch all four decoders on the board. Knowing whether its four or five will help in deciphering what the addressing problem is and where you need to look for an answer.

Yes exactly. It is the top 4 yellow lights (from left to right) that are giving me a problem, but sometimes the 5th will flicker too making the entire top row a problem. The rest of the yellow lights in the maze are fine. All red lights are fine as well.

#12 5 years ago

I had the machine on for a while just sitting. Seems to problem gets much better/pretty much goes away when the game warns up. Is that any help in diagnosing?

#14 5 years ago
Quoted from Superchicken:

OK. I’m thinking it is AD1 to the decoders. So on the MPU that would be:
J1 pin 14
U10 pin 3

Ok. How do I go about testing if this is the case? Thank you for all your help so far too.

#16 5 years ago

Ok cool. I'll give it a try and report back.

5 months later
#17 5 years ago

Believe it or not, life got in the way and I just got back to the machine this afternoon. Wound up being a bad connector. Repinned and replaced housing and all is good.

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