(Topic ID: 214242)

Bally static / white noise


By msadan

1 year ago



Topic Stats

  • 9 posts
  • 4 Pinsiders participating
  • Latest reply 1 year ago by msadan
  • Topic is favorited by 1 Pinsider

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#1 1 year ago

I have a Harlem Globetrotters that always has a faint "white noise" sort of sound, sounds just like when the TV station went off the air at night (if any of you are old enough to remember that). All of the regular game sounds are there, there's just a noticeable static-like background noise. It starts immediately when the game is turned on and never changes, although it will get louder / softer if the volume is turned up / down. Grounds are all good, connectors are good, all new caps on the sound board. Any ideas?

#2 1 year ago

I still point an angry finger at grounds whenever I have static. Weird thing, but check continuity between your cabinet ground and your head ground. Make sure that's nice and solid.

#3 1 year ago

Try the sustain pot as well... although I don’t think I can get mine to deliver white noise kind of static, usually just the last note lingering.

#4 1 year ago

That sound board is sensitive to ground loop problems. The 43v to 12v regulator has a different ground return than the 5v circuit stuff. If the ground is not at the same potential you get a buzzing or humming.

Try simply pulling the board off of the backbox grounding mounts. If that fixes it you have grounding issues.

#5 1 year ago
Quoted from srcdube:

Try the sustain pot as well... although I don’t think I can get mine to deliver white noise kind of static, usually just the last note lingering.

Replaced both pots when I replaced the caps.

#6 1 year ago
Quoted from barakandl:

That sound board is sensitive to ground loop problems. The 43v to 12v regulator has a different ground return than the 5v circuit stuff. If the ground is not at the same potential you get a buzzing or humming.
Try simply pulling the board off of the backbox grounding mounts. If that fixes it you have grounding issues.

Yeah, I’ve seen that before with humming. Tried isolating the board from the backbox ground, no help. All the ground problems I’ve dealt with caused humming / buzzing. This is the first time I’ve run across this type of noise.

#7 1 year ago
Quoted from CadillacMusic:

I still point an angry finger at grounds whenever I have static. Weird thing, but check continuity between your cabinet ground and your head ground. Make sure that's nice and solid.

Grounds are definitely solid. This is a different noise, more of a hiss / white noise. Most of the ground problems I’ve seen cause a hum.

#8 1 year ago

I'd suspect the volume control amp, main amp or maybe 4049. You can check by pull them out one at a time starting closest to the digital side and see if it goes away.

Be aware that the the new make 741 may not work properly in a -32 board.

2 weeks later
#9 1 year ago
Quoted from barakandl:

I'd suspect the volume control amp, main amp or maybe 4049. You can check by pull them out one at a time starting closest to the digital side and see if it goes away.
Be aware that the the new make 741 may not work properly in a -32 board.

Got it! finally had a chance to get back to this. Replacing U10, the LM380N audio amp took care of it.

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