Why do all pinball machines hum ?

[Caveoftreasures]

Why do all pinball machines hum ? Even BNIB Sterns hum ?

Is there a way to get rid of a hum noise you hear in a quiet room coming from every pinball incl the brand spanking new ones ?

It's annoying cause nothing else in the house that is electric hums ?

Do others get annoyed by the hummmmm. ? Anyone got an easy fix ?

Brett

[robm]

From what i understand, it is a harmonic from the laminations in the transformer.

WPC 95 titles are he worst where the tranny is mounted on the rear of the cabinet. A good solution for those is to put some rubber (eg: bike tube) under the mounting points of the transformer, and it decreases very significantly

[pinnies4me]

They are happy.

[Pop Bumper Pete]

What annoys me is when after a game is over, the machine does not stop the music, it just turn the volume way down
CFTBL, I am looking at you!



They hum because they don't know the words

[Toads]

They hum because they don't know the words

That's very good Pete :)

[Mr Pinbologist]

They hum because they don't know the words

That's very good Pete :)

It could also be because they like the songs!! 

That used to be my old boss's favourite thing to tell customers who would bring in an amp for repair and say "it hums"!! his response was usually "maybe it likes the tunes" 

[Caveoftreasures]

Is there a technical fix that one can add to a brand new row of Sterns to stop the constant hum ?

On a machine like a 1990 TMNTurtles, it hums in unison to the lights flashing and doing its visual and audio attract more. I expect it from older designed machines that have been operating for say 25 years etc, but brand new machines in 2014 ? It just seems like it could/should be a easy technical fix ?

Hoping someone like Homepin or Retropin gives an opinion as well cause these guys play with transformers daily for commercial reasons.
Thanks for the serious opinions so far. Lol

Maybe the machines hum when people stop slapping the shit out of the flipper buttons. Lol

[Retropin]

Its caused by stray magnetic fields from the transformer, also known as Edi Currents. Its due to the frequency ( in this case 50hz) of the AC cycle.
you can lessen it by tapping the iron core to ground and also installing a Faraday cage and tapping this to ground... the cage on SS games is just this

[McKie1]

Our stern ST hummed from day one and I put it down to the fluoro. I replaced it with one of the led kits and no more hum (well at least not one I can hear). Just our example; not very scientific though :)

[GORGAR 1]

Our stern ST hummed from day one and I put it down to the fluoro. I replaced it with one of the led kits and no more hum (well at least not one I can hear). Just our example; not very scientific though :)

Same here it's the ballast apparently :)

[McKie1]

Weird how louder than other modern sterns though! Just need to crank sound to compensate. Lol

[Retropin]

The load on the transformer also plays a part which is why swapping the ballast may make a difference.. its all down to harmonics and the circuit impedance will also determine the amount of hum

[Brunswick Brawler]

The hum you hear is "50Hz" hum from the 'AC' (alternating voltage and current) that powers the transformer and coils.

The coils are having their applied energy reversed and reversed back 50 times each second.   Each cycle moves the coils winding and any transformer laminations (metal plates).  So the 'metal' is 'rocked' 50 times a second, and it's that vibration that you hear.

The hum is more prominent in EMs, as they have a heap of relays that are all AC powered.  Regarding NIB, I'd say get a better quality transformer.  The looser the winding, the louder the hum.  I think Toroidal transformers produce less hum.

...'AC' be a good name for a heavy metal rock band. It might sound better if you add 'DC' even though DC (direct current) doesn't 'rock' the 'metal'!


(Tech geek stuff: You should be able to get rid of EM flipper hum if you rectify the voltage from AC to DC - but this needs to be done properly as a fully rectified voltage will need to be stepped down in voltage to not overheat and burn out the coils.  An after market idea for someone who can be bothered making and selling proper 'flipper zero hum rectifiers'.)