Hi Martyj - Martyw here 
It's probably no use shielding the hummy speaker if it's being driven by a hummy signal.
Quite possibly, the hum is coming from the main PSupply board, and you should probably make sure the caps in the main PSupply board are correct.
Depending on the type of buzz (i'd have to hear it) does your machine have a switchmode Psupply in it?
I'm assuming some newer machines do have these?
At worst case, it's simply poor design, and no doubt can be modified to cure the shortcuts the manufacturer made 
I'm in Melb too, happy to assist if required, i seem to always be at markc's these days hahahahaha.
Oh yeh, good luck *NOT* buying something at markc's, everytime i go there i buy something hahahaha.
Supporting the cause .....
Marty.
Hi Marty,
I suspect your right about the signal which is driving the speakers. I have read post after post on google in relation to this. (a) it is very common on D.E's - which everyone on here as also stated correctly. I guess I need to remember that these machines were designed for arcades not homes.
The noise is a humm when just sitting there in attract mode and I get some G.I interference as well. I've replaced the main cap on the sound board, all backboard screws in and tight and I replaced the -12v cap on the sound board last night. Still the same.
I have a D.E Simpsons sitting next to it, and it is much much quieter. The Simpsons though looks like its had very little use in its life...
I recall reading a thread about AC leaking onto the -12vDC but I might be getting confused.
Martyj and marty
you 2 play nice
now who got the f14 ?
you will fidn teh buzz is also in ballys williams too , mostly transformer noise
there are a few way to fix this even duckie can do it ....
You havn't sold the F14 (nooooooo)....I was really really hoping you would pop on a red cap and leave it under my xmas tree!
If there is a way to fix transformer noise I'll give it a go!
