Jules Richardson wrote:
Picked up an old Kenwood tuner/amp for nowt a couple of days ago - I love
all that old 70s/80s hi-fi stuff. All seems to be working, but has a
major case of the crackles when the volume control or input selector are
used. Despite all the putzing around with vintage kit I've done over the
years, this is the first thing I've had where it seems like the pots and
switches could do with a good clean.

So... does isopropanol work? I've used it on all sorts of other
electronics-related cleaning tasks over the years, but I've seen mixed
reports online about it for use with pots, with some folk saying it's OK
and others saying it'll destroy lubricant inside the mechanism (the
latter does seem like a valid concern, but I'm just not sure if it's
being over-cautious - or if whatever lubricant was used has long since
ceased doing a useful job in this thing anyway) .

What about ipa to clean, followed by a little mineral oil down the pot/
switch stem to work as a contact lubricant? Or is that asking for
trouble, too?

I'm trying to avoid the week's wait it'd need to get some conctact
cleaner shipped here - but if that's the way it has to be, then so be
it :-)

Switch cleaner would be better for the pot. The problem may be wear of
the track rather than dirt, though, on an amp of that age. I've seen
pots where the base material has been visible through a gap in the
resistive maerial. For the switch, any contact cleaner should do the
job, just check to make sure the plastic isn't going to be affected by
the IPA.

Crackling on volume controls is often caused by DC leakage through
coupling capacitors, so check those, too.


--
Tciao for Now!

John.