I just purchased a Hafler 110 preamp. I powered the preamp, no blown
breakers, sparks or burning insulation :-) I dropped it into my system
to put it through its paces and all seemed well until I started pushing
the four push button contols; mono, filter, tone and epl. When I pushed
the "filter" button the volume of the right channel dropped 80%.
Cycling that button produced a few crackles, but no improvement. I
understand that this a common problem with Hafler push buttons. Does
anyone have experience opening the plastic switch box for chemical
cleaning? I'd like to squirt some Deoxit inside, but dread breaking a
switch. I've thought of using a hot needle to melt a hole and putting
the aerosol needle in that. If worse comes to worse, are there
replacement switches available?

Hello,

I've had some success by removing the plastic knob and dripping the
cleaner down the shaft, working the button in and out as you do it.
Sometimes it helps to stand the preamp so that the front panel is facing
the ceiling, so the fluid can be helped by gravity. Some switches have
a plastic collar just behind the knob, so you have to remove the panel
(or the switch) to get to where the shaft enters the body of the switch.

Regards,
Tim Schwartz
Bristol Electronics


wrote:

I just purchased a Hafler 110 preamp. I powered the preamp, no blown
breakers, sparks or burning insulation :-) I dropped it into my system
to put it through its paces and all seemed well until I started pushing
the four push button contols; mono, filter, tone and epl. When I pushed
the "filter" button the volume of the right channel dropped 80%.
Cycling that button produced a few crackles, but no improvement. I
understand that this a common problem with Hafler push buttons. Does
anyone have experience opening the plastic switch box for chemical
cleaning? I'd like to squirt some Deoxit inside, but dread breaking a
switch. I've thought of using a hot needle to melt a hole and putting
the aerosol needle in that. If worse comes to worse, are there
replacement switches available?

Thanks for the suggestion. I removed the face plate, stood the preamp
so the four switches faced "up", applied copious amounts of deoxit,
let the deoxit work for an hour or so and then cycled the switches a
dozen times. I would never have thought that the deoxit would penetrate
down the shaft, but it seems to have worked. I'm keeping my Mototool
handy though :-)