(Topic ID: 168323)

TOM Humming noise


By Robl45

3 years ago



Topic Stats

  • 27 posts
  • 11 Pinsiders participating
  • Latest reply 3 years ago by burtcam
  • Topic is favorited by 2 Pinsiders

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Linked Games

#1 3 years ago

My TOM appears to be humming, it appears to be making noise from the speaker as well as the DMD. Two different humming noises. I quickly took a look right now and if I unplug the power to the dmd, one of the humming stops. What is the first step in troubleshooting this?

#2 3 years ago

Anyone? I thought this was common but I can't find much on it.

#3 3 years ago

Weird. Is it a 60hz hum? Sounds like a grounding issue if it's coming out of the speaker. Plasma displays can make a noise as well, some kind of feedback. Maybe check to make sure everything is properly grounded?

#4 3 years ago

I don't know. It hums louder and softer. Dmd seems to just have Steady hum which I understand is relatively normal. Another site had an old post saying something about it could be the caps on the sound board but I'm not really sure where to start trouble shooting. Another thread said something about isolating the board off the backboard, but I'm not sure that was for bally williams Games.

#5 3 years ago

Definitely tighten all the screws holding all the boards on the backbox. I had a subtly hum once in my old whirlwind and that seemed to do the trick (if I remember correctly).
Does your DMD cable have that magnet clasp around it?
I may be wrong but I believe that is there to "absorb" any stray current from the ribbon cable that could interfere with the speakers?
LTG is a good resource to reach out to with situations like yours.
He's helped me numerous times over the years.
I feel like I should adopt an animal and name it LTG in his honor

#6 3 years ago

It's only humming because it doesn't know the words.

Is the DMD a Cherry-branded one, by any chance?

If you turn off the game, completely disconnect the DMD, and then turn the game back on, is the hum gone?

#7 3 years ago

If I disconnect the dmd, the hum is gone from the DMD, the speaker hum is still there. Its not ridiculous, but you can definately hear it. I just setup the games again after 6 years, so maybe they all hum like this?

#8 3 years ago

I have TOM, and it definitely does not hum. I think jsa is on to something with the grounding issue.

#9 3 years ago

One way to check the capacitors in the game is to look at the surface of each capacitor (the top, flat side of the cylinder). If there is any bowing out of the capacitor, they are failing and need to be replaced. Given the pinball machine was sitting for six years unused I wouldn't be surprised if this was an issue in multiple places. That being said, I'm originally an audio engineer, and hums were often related to bad grounding (which is why tightening the screws can help, since in theory the pcb panel is well grounded).

I'm sure there is a proper way to test capacitors with a multimeter, I'm just electrically challenged so someone else can comment on that.

#10 3 years ago

Mine hums as well from the speakers. Anxious to see the solution

#11 3 years ago

I just checked the boards and they are tight, still humming away. Unfortunately check the grounds doesn't mean much to me, thats why I"m posting here, need more of a step by step of what to check.

#12 3 years ago
Quoted from Robl45:

I just checked the boards and they are tight, still humming away. Unfortunately check the grounds doesn't mean much to me, thats why I"m posting here, need more of a step by step of what to check.

"Check the grounds" means check all the ground connections. Each board has at least one ground connection. Sometimes a break is caused by a cold solder joint, a bad crimp on a pin, a broken wire, dirty pins/connectors, etc.

Use a multimeter in diode test mode to check for continuity.

#13 3 years ago

Its your transformer. Williams changed the position from the bottom of the cab to mounting it to the back of the cabinet, from memory people put rubber under the transformer mounts

#14 3 years ago

I didn't see grounds to the boards, but any grounds I do see do seem tight, I can take a look at the transformer a little later.

#15 3 years ago
Quoted from Robl45:

I didn't see grounds to the boards,

You would have to look at the schematics. They are wires in the connectors.

#16 3 years ago

My TOM did the same thing, I tightened all the screws holding the transformer in the back of the cabinet and it all but eliminated it.

#17 3 years ago
Quoted from PURPLEBAT:

My TOM did the same thing, I tightened all the screws holding the transformer in the back of the cabinet and it all but eliminated it.

You mean it didn't help, right?

#18 3 years ago

No no, it reduced the humming to almost completely gone.

#19 3 years ago
Quoted from Kiwipinhead:

Its your transformer. Williams changed the position from the bottom of the cab to mounting it to the back of the cabinet, from memory people put rubber under the transformer mounts

That is correct ..
Put some insertion rubber and that should solve the issue with transformer Hummmm.
i have just been to lazy to do mine ...

#20 3 years ago

Insertion rubber?

#21 3 years ago

I just tried tightning the transformer screws, no difference.

#22 3 years ago

Does the actual sound in game raise or lower on it's own without you touching the volume? I had a Stern SM that had a nasty hum, but the sound was messed up along with it in the way described above. After much messing around with tightening down screws etc...I found it to be that someone installed the wrong type of diode on one of the main boards. After replacing the part with the correct one the hum went away and the sound returned to normal. My point is make sure that no one modified the boards with the wrong component. Sometimes hard to find, but can cause this type of problem.

#23 3 years ago

Is the hum one consistent sound that doesn't change in pitch or volume after the game is on, and independent of whether a game is being played or not?

#24 3 years ago

Its not too loud right now, its changing in tone when the lights flash in attract mode. Sound is fine in the game, just makes a hum, I don't think its really hurting anything just annoying since the games are in my home office with me.

#25 3 years ago

Do you have LEDs? Could be Electromagnetic Interference (EMI) caused by some. LEDs and poor insulation

#26 3 years ago

No LED's standard bulbs/

#27 3 years ago
Quoted from Robl45:

Insertion rubber?

It is a natural rubber, with one cloth layer (inserted)
or 2 cloth layer depending on the thickness

ebay.com link

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