game: #WhoDunnit WPC-S , 1995

There is a humming sound coming from the machine, its not audible at all during gameplay, but in attract mode it makes 10x more sound than my other machines, so i guess something is wrong.

I dont think it is the back-box speakers or the cabinet speaker.
However it feels and sounds like its coming from the WPC transformer.

Any clue what might be the solution for this?

My best
M

Thanx guys, gonna try the rubber mallet smacking thing first

Hmm... tried the following:

Switched machine off.

Unplugged it from the wall.

Smacked transformer hard a bunch of times with rubber mallet.

Turned machine on, but "singing" still present.

I have done this maybe 5 times now.

Look at attached image, i am only able to smack it hard enough on the upper side.

Am i smacking it "wrong"?

Might it be something else?

transformer (resized).jpg

Yes, that probably explains it, i was just now noticing that on my TZ, the transformer was oriented different, with the "USA angle".

Ok i will try remove it and smack away.

Btw, is there any risk for me handling the transformer ? Is it carrying a residue charge? ( after unplugged from the wall ofcourse ).
Thanx Vireland

So i unmounted the transformer, smacked it again, but it was still "singing".

Then i removed the metal cover, and.. "singing" gone.

Anyone know what that metal cover is for?
Might it be to evenly distribute ground along from the ground-wire visible in the image above?
Is there a risk to remove it ?

Will it be enough to have the ground touch the one side of the transformer as visible in the image? The ground would then still be between the metal foot and the wood.

Agreed.

But, on a sidenote:
On my TZ and my STTNG the transformer actually is mounted on wood in the bottom, center of cab.
There is however a second layer of wood there, with space between.
Is this layer ment for mounting of the transformer alone?
Would there be any logical reason the transformer should not be mounted on the cabinet-wood directly?

Yes, but in my case what worked was to remove the metalcover, or am i wrong?
The tiny vibrations between transformer and the cover was the singing, not the transformer itself.