(Topic ID: 152744)

Help! - Speaker white noise


By gac

3 years ago



Topic Stats

  • 26 posts
  • 8 Pinsiders participating
  • Latest reply 3 years ago by gac
  • No one calls this topic a favorite

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#1 3 years ago

I have a Creature pin that has white noise or interference coming from the speakers. The speakers work and the game sound comes through but the white noise is still there, and is especially noticeable in attract mode. It seems to be affected by the back box lights blinking patterns and by the activation of leds on the speaker panel mod that the machine has. I'm guessing this is probably a grounding issue somewhere but I can't put my finger on it. There is a green ground wire coming from the ground strap in the back box that is connected to the left speaker on the speaker panel. I tried reseating the ribbon cables on the CPU to the flipper board to the sound board but it had no effect. Any thoughts on what to look for to fix this are greatly appreciated. Thanks in advance.

#2 3 years ago

Try swapping sound boards and see if it goes away.

#3 3 years ago

White water and taf are compatible swaps in your collection.

#4 3 years ago

Thanks guys. I will try to get a chance to swap the boards. If the problem goes away, I would assume it is safe to say that there is a problem with the board. Then I guess I would contact one of the well known repair guys here on pinside for a fix. I wonder if this is common and an easy fix for those who are experienced at working on these boards.

#5 3 years ago

Is there anything that I could try/look for before swapping out the boards? Thanks

#6 3 years ago

By white noise, is it overly loud, like 50% of the total output? White noise bleed is normal on pins, like up to 20% of the volume even. There is hardly a thing you can do about it, due to the design of these games. I've yet to come across one from the 90's and earlier that doesn't experience this.

You can try and float the ground of the sound board by using nylon screws and standoffs/washers to keep it off the metal backing of the backbox. That may help slightly, but since the audio ground is not isolated, it will always be subject to interference from the ac on the lamps.

Sometimes just tightening the grounding/mounting screws helps a lot too.

#7 3 years ago
#8 3 years ago
Quoted from thedefog:

....
You can try and float the ground of the sound board by using nylon screws and standoffs/washers to keep it off the metal backing of the backbox. That may help slightly, but since the audio ground is not isolated, it will always be subject to interference from the ac on the lamps.
Sometimes tightening the grounding/mounting screws helps a lot too.

exactly what i was going to say.

#9 3 years ago

Thanks for the advice. I've made sure the grounding/mounting screws are tight as I thought that could have an impact but it had no effect. I'll try nylon screws and washers. Are these available at a regular hardware store or do you know offhand if the regular parts people (Marco, etc.) stock them? Thanks again for your help.

#10 3 years ago

When I was troubleshooting sound issues on SS (WPC95) I found the needed nylon screws and washers etc at the local Lowes store.
Make sure your speaker wires are away from GI /insert wiring if possible, and that you have the ferrite magnet cores on the wires as well.

#11 3 years ago

start by floating your board first, that way you'll know if the problem gone.

#12 3 years ago
Quoted from beatmaster:

start by floating your board first, that way you'll know if the problem gone.

Exactly. No need to take a trip to the store to test that theory out either.

#13 3 years ago
Quoted from beatmaster:

start by floating your board first, that way you'll know if the problem gone.

On my Data East JP, I only needed to place a nylon washer under the screwheads themselves, and NOT under the board, between the metal backplate. There are no PWB traces on the backside of this board to make contact with the backplate.

"Floating" the soundboard in this manner eliminated 90% or more of the hum on my JP. Was sooo annoying beforehand, now just an afterthought.

#14 3 years ago

Ok so I put nylon washers on the sound board and it has improved the white noise a bit. It seems the biggest source of the interference is from the led speaker panel mod. The power for the led speaker panel mod comes from a tie-in connection at J116. When the mod is connected, the noise is much worse. When disconnected, the noise isn't that bad now. It seems that even when the mod is disconnected that the little bit of white noise now is most noticeable when the lights (type 86 leds) on the circular ramps illuminate in attract mode. Any thoughts on possibly grounding the speaker panel mod or is there another location that I could connect the power for the speaker panel mod? Thanks everyone.

#15 3 years ago
Quoted from gac:

Ok so I put nylon washers on the sound board and it has improved the white noise a bit. It seems the biggest source of the interference is from the led speaker panel mod. The power for the led speaker panel mod comes from a tie-in connection at J116. When the mod is connected, the noise is much worse. When disconnected, the noise isn't that bad now. It seems that even when the mod is disconnected that the little bit of white noise now is most noticeable when the lights (type 86 leds) on the circular ramps illuminate in attract mode. Any thoughts on possibly grounding the speaker panel mod or is there another location that I could connect the power for the speaker panel mod? Thanks everyone.

did you tried floating the board?
i'm curious, remove the screws holding the board, make sure the board touch nothing.

#16 3 years ago

Hi beatmaster - Actually, no... I didn't try to float the board. I will do that tomorrow. If I do float it and the problem goes away, even with the speaker panel mod connected, what does that mean? What would be my next step? Thanks for your help

#17 3 years ago

ground loop somewhere.
next step, nylon screws.

#18 3 years ago

Actually I did install nylon screws too.

#19 3 years ago

floating the board probably won't change anything if you used nylon screws.

1 week later
#20 3 years ago

When I disconnect the led speaker panel mod the white noise is minimal. It has to be a grounding issue with the speaker panel mod. I'm just not sure what to do to ground it properly.

#21 3 years ago
Quoted from gac:

When I disconnect the led speaker panel mod the white noise is minimal. It has to be a grounding issue with the speaker panel mod. I'm just not sure what to do to ground it properly.

You don't. That is the trick.

#22 3 years ago
Quoted from thedefog:

You don't. That is the trick.

Ummm. Ok.

#23 3 years ago

Remove the mod
In all seriousness though, you have to isolate the ground loop you introduced with your LED mod.

#24 3 years ago
Quoted from thedefog:

Remove the mod
In all seriousness though, you have to isolate the ground loop you introduced with your LED mod.

How do I do that? Thanks

#25 3 years ago

Does the speaker LEDs have a color and brightness controler on it? If so, when you dim the leds does it causes more noise? Can you move the controler to a different spot like down in the cabinet?

#26 3 years ago

Hi Grumpy - They aren't speaker leds. It is the led speaker panel mod by Jeff Thompson. The leds light up the taillights of the cars on the speaker panel and a few other items on the panel. No brightness controller or ability to dim. Thanks

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