KVR Audio

mztk · Post by **mztk** » Wed Mar 12, 2014 2:56 pm

my old tx81z has always had a bit of an electro-mechanical hum:
it is old and has been around, and the transformer is probably a
bit loose.

i read that you should tighten everything up. will that work?
how about adding a bit of 2-part strong flexible adhesive between
it and the chassis? if so, how much should be used? just a film or
a good blob? what is the type of adhesive/compound to use?

Phil999 · Post by **Phil999** » Wed Mar 12, 2014 4:47 pm

I found two methods that work well:

- the one method you mentioned, tightening everything to prevent vibration. One way not mentioned is to stick wood between the PSU and the chassis.

- put the PSU outside the chassis, on a plank of wood. You must add a "Danger" sign and prevent children and animals to enter the room with key locks.

noizetronic · Post by **noizetronic** » Wed Mar 12, 2014 5:09 pm

- rubber washers into the transformer mount and the PSU/PCB mount
- a bit of hot glue onto the base of coils (only if they're not getting too hot during use)

mztk · Post by **mztk** » Wed Mar 12, 2014 6:08 pm

ah so the coli etc. inside can be loose/vibrating too?
to be honest i haven't even ever opened it up

Phil, i know why you're called 999...

lfm · Post by **lfm** » Wed Mar 12, 2014 6:53 pm

noizetronic wrote:- rubber washers into the transformer mount and the PSU/PCB mount

Especially a chassi mount transformer can become dead silent with rubber washers. I did that to a rack unit.

I have another one with PCB mount transfomer, and it's more difficult and no screws or anything like that. So mechanical noise transfer to MB and then into chassi unit.

It helped quite a bit to put damper selfadhesive on the plastic joint towers that support MB in unit. Maybe down 20dB or so.

I had a TX81Z with that problem in the 80's, so it seems to be a common problem. But never looked inside that unit to see if possible to do anything.

Best Way to eliminate mechanical hum on PSU?