(Topic ID: 111188)

Can LEDS cause speaker hum?

By Dawson

9 years ago


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  • 20 posts
  • 10 Pinsiders participating
  • Latest reply 7 years ago by billycrna
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#1 9 years ago

Just put some LEDS in the inserts of a high speed and now have a speaker hum that wasn't there before

Nothing has changed , went over my work a couple times . "It's a fricken light bulb ..right"!

Maybe it's the pulse of the "strobing effect"? Other G.I. Have gotten dimmer and pulse as well

Has this happen to anyone else.

Thanks

#2 9 years ago
Quoted from Dawson:

"It's a fricken light bulb ..right"!

Wrong. It's really a diode and has almost zero comparison to a light bulb electrically.
I've never heard of LEDs causing hum before, the "strobing" effect is because the LEDs by nature are not happy with an AC supply source. They switch on and off sharply as the the AC current flow changes direction.

Perhaps you have an audio signal wire too close to GI wire somewhere, and you are picking up the noise through mutual coupling. Not sure, I've never heard of LEDs causing speaker hum. I would change the bulbs back to incandescent as a test to see if the hum goes away first.

What brand of LEDs are they?

#3 9 years ago

hmmmm.. might be possible to half-wave rectify the GI line with a big diode, at a little sacrifice to voltage supplied to the LED's, may solve it quick-easy, may or not dim your LED's too.

#4 9 years ago

They are pinball bulbs ,the non ghosting good ones. Would those make incandescent 44's in the G.I.'s dim a bit, the bulbs below the slings seems stressed , as I believe the NG type bulbs have a small resister in them?

I can live with the hum because they look so fricken good

Thanks tj

#5 9 years ago
Quoted from Dawson:

They are pinball bulbs ,the non ghosting good ones. Would those make incandescent 44's in the G.I.'s dim a bit, the bulbs below the slings seems stressed , as I believe the NG type bulbs have a small resister in them?
I can live with the hum because they look so fricken good
Thanks tj

They should not make the GI dim, because the LEDs draw much less current as an incandescent. You also do not need to use the non-ghosting style of bulb in GI. Ghosting is when an controlled lamp LED glows dimly when it should be off, and occurs because of timing issues in lamp matrix controlled games.

#6 9 years ago

Yeah I do not use NG type bulbs in the GI's...

And yeah I realize they do draw less power , just seems weird... Not sure why the left half I simmer then the half

#7 9 years ago
Quoted from Dawson:

Yeah I do not use NG type bulbs in the GI's...

You just said they were??? I'm not following.

Quoted from Dawson:

They are pinball bulbs ,the non ghosting good ones.

#8 9 years ago

I just changed my high speed out with comet LEDs and had to clean some of the sockets. This made them brighter.

#9 9 years ago

Wayout... Sorry I misspoke, I'm uneducated in proper typing skills and sometimes just talking on paper seems to be an undertaking

For the insert "controlled" lamps I always go NG , for the global I also use regular LEDs , and I always use pinball bails , I just had the best luck with them and the shipping takes a day ..

Bax, yeah good call , I need to get a couple tools to clean sockets , like a brass pipe cleaner of te right size , what do you use ? Funny the dimness is only on one side , just coincidence I'm sure ..

#10 9 years ago

I couldn't comment on why or why this isn't happening, but I did just LED a High speed to make our kit and didn't have any of the same issues after. used all PB bulbs too

I used regular bulbs in this game as it doesn't ghost. Not sure if randomly that would potentially matter though

Quoted from Dawson:

Bax, yeah good call , I need to get a couple tools to clean sockets , like a brass pipe cleaner of te right size , what do you use ? Funny the dimness is only on one side , just coincidence I'm sure ..

This sounds like your game may have a more underlying issue. Shouldn't matter what bulbs you use, the inserts should be the same brightness all around. Having it be on one side helps narrow it down to a wiring issue over there

#11 9 years ago

i cant think of any way that LEDs could cause either speaker hum or incandescents to become dimmer. is it possible the LEDs are just making the incandescents look dimmer, or are causing you to pay closer attention to problems you hadnt noticed?

maybe you could somehow disconnect the lighting, turn on the game, and see if the hum is still there.

#12 9 years ago

Why not just unplug the lighting circuits and see if the hum goes away?

#13 9 years ago

I used a red 3m pad and twisted a small piece around in the socket. This was only on a couple sockets. If one side is dim you may want to check you connectors on the boards

#14 9 years ago
Quoted from Bax1:

If one side is dim you may want to check you connectors on the boards

+1 get the GI working correctly with standard bulbs. GI circuits are usually divided into branches on many games, and if your GI connectors are dirty, burned or otherwise faulty at the boards, you should address those issues first.

#15 9 years ago

My WOZ RGB LEDs cause speaker hum. It's loudest when they are white.

#16 9 years ago

what-why I'd mentioned rectifying (or half wave) the lines feeding to GI, LED bulbs having little bridge rectifiers in them for the LED itself to see DC regardless AC (polarity switching alternately)..
so it might be possible those tiny bridges swapping chops are causing some noise if the lines are close to something audio (especially if low level and poorly shielded). it might help, without tearing into wiring to separate-isolate-redo a bunch of stuff, might also lower the voltage a bit, dont know if it would be visually perceptible or not, but it'd sure be easy-cheap to try it or undo it. could also try popping in a little bridge rectifier to GI lines, swapping polarity outgoing might make differences even though the rectified LED bulbs wont care whether AC or DC (or DC polarity).

the idea is to get them just passing DC along to the LED itself, taking the switching action of the bulbs rectifiers for being fed AC out of the picture as a possible noise source. I could be wrong, but it's something I'd at least try, for it being pretty cheap quick and simple, kinda makes sense to me.

#17 9 years ago

Older games were not designed for LEDs so this is not a surprise.

Quoted from Pimp77:

My WOZ RGB LEDs cause speaker hum. It's loudest when they are white.

Same here. This is due to a terrible electrical design by JJP. The new LED Sterns don't have even the slightest hum or buzz.

#18 9 years ago
Quoted from John_I:

Older games were not designed for LEDs so this is not a surprise.

Same here. This is due to a terrible electrical design by JJP. The new LED Sterns don't have even the slightest hum or buzz.

Have you found a way to reduce the hum...it's only noticeable in attract mode to me, so it's not THAT big of a deal.

#19 9 years ago
Quoted from Pimp77:

Have you found a way to reduce the hum...it's only noticeable in attract mode to me, so it's not THAT big of a deal.

Nope. I had to open it up this week because it would not boot. Turned out to be the hard drive cable as Lloyd suggested. While I was in there I looked at all of the cables that might carry sound to make sure they were fully mated and not running near other cables that could cause interference. I might have another go of it at some point when I am not working on another problem at the time.

2 years later
#20 7 years ago

I just received my WOZ 75th. Crazy speaker hum.....really annoying. I moved around a couple of wires that goto the speaker and it reduced it some, but not completely. Is there no fix for this? Also, the first six LED's on the yellow brick road seem to be a bit dimmer than every other LED in the game. It's this way even during the white test. Are all games like this? Or is this a problem that I need to address? Thanks guys!

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