(Topic ID: 190930)

Help educate me regarding stuck on switched lamps

By colonelsnow

6 years ago


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Topic Stats

  • 11 posts
  • 5 Pinsiders participating
  • Latest reply 6 years ago by wayout440
  • Topic is favorited by 1 Pinsider

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#1 6 years ago

I am trying to trouble shoot some stuck on switched lamps on my Eight Ball Deluxe.

If I go into the Lamp Test the "stuck on" lights flash like they should. Do this mean that they are not shorted to the GI ground?

#2 6 years ago

If they turn off then they can't be shorted. Are you sure they're not just dimming from the power draw?

Have you tested the transistors?

#3 6 years ago

Did it work before and just started happening? Are they incandescent bulbs or cheap LEDs? If they are LEDs try swapping a bulb in.

#4 6 years ago

They are definitely flashing. The function of the built in lamp test is to flash all the switched lights.

#5 6 years ago

Yes, the transistors test good

#6 6 years ago

Check for bad solder joints, esp on J4. They're stuck on in both attract and game? Do they come on as soon as you hit the power or not until it boots?

#7 6 years ago

If they flash in test mode, the lower level control logic is good. Your problem is not transistor,scr, bulb etc. The problem is an upper level logic issue. Are you sure these lamps are not supposed to be on to begin with? Which are the exact lamps in question?

#8 6 years ago
Quoted from wayout440:

If they flash in test mode, the lower level control logic is good. Your problem is not transistor,scr, bulb etc. The problem is an upper level logic issue. Are you sure these lamps are not supposed to be on to begin with? Which are the exact lamps in question?

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#9 6 years ago

Was this game working fine and then these all failed at once?
Any signs of battery corrosion on the MPU board?
Did you do anything at all, such as change ROMs or some component on the MPU?

Some of the lamps not acting right in your list are controlled by the aux lamp driver board which gets instruction data from the MPU, so I would be leaning toward a problem with that MPU board. All the lamps work in the same way, they are turned on with a transistor switch and not through a matrix. If it's flashing when instructed by the test mode, I can be quite certain of what isn't the problem, it's just that I am not sure exactly where...and I don't want to steer you wrong. I've never seen this exact type of problem before, so hoping that someone else chimes in with a second opinion. Would you have access to another MPU board to swap in?

#10 6 years ago

EBD uses an aux lamp driver board. The decoder circuits on the aux board fail 10x more often than logic on the main lamp driver board.

OP, can you check to see if all non workings lamps are associated to the aux lamp driver board? If so you can focus on the aux board.

If the stuck on lamps are on both the aux board and the ldb. The problem is on the MPU or more likely, MPU J1 connector. Find common decoder bits in common to non working lamps. There is 10 bits of data that control all the lamps. Four address, Four data, and two enables. The address and data are used on both lamp boards (not all used on the aux) and then one enable (strobe) is for the aux, other for main LDB. Easiest way to find a dead address/data bit is to logic probe past the MPU j1 plug. If you find a bit stuck there, then you check at the PIA to determine connector or MPU problem.

#11 6 years ago

Perfect, you da man.

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