On 2/10/2014 10:34 AM, Phil Allison wrote:

Hi,

ever since someone had the brain wave of putting "computer" fans
inside power amps - service techs have had to deal with dust and
fluff clogged heat sinks and filthy PCBs.

When such amps are installed in a music venue for years, cigarette
smoke, artificial fog oil and moisture add to the mix making the
result truly appalling.

In most cases thorough vacuuming and cleaning inside and outside
surfaces with a damp cloth is sufficient. I know of techs using
compressed air, but that seems terribly messy to me.

However, some example are so badly fouled the only way I have found
to clean them properly is to submerge the PCB and heatsink assemblies
in hot water and detergent and scrub them just like dinner plates and
saucepans. In order to thoroughly dry the PCBs, I have used an oven
set to low temp, hot air from a room heater or gun and simply the sun
on a warm day.

This is obviously a very time consuming process requiring a lot of
disassembly and reassembly, cleaning the fans themselves is one of
the most tedious parts.

Recently I had to clean a couple of Crown XS700s that were completely
fouled with black fluff that proved to be electrically conductive !!

Turns out they had been in the same rack with another amplifier that
went up in smoke, filling them with carbonised fibreglass soot. This
took more than the usual amount of time and care since a 2kW SMPS is
built on the same PCB.

Anyone know an easier way or have useful comments?


[DISCLAIMER] None of what follows will be remotely helpful.

**Ah, that brings back memories. I used to keep a 5 Litre container of
Freon TF™, along with several spray cans (they even supplied a nifty
clip-on brush thingy). Brilliant stuff. No residue, did not hurt
plastics, non-flammamble, disolved the nastiest greases and oils, not
harmful to humans and possessed a low vapourisation temperature.

The perfect cleaner. Bummer about the ozone layer. The stuff was banned
decades ago.



--
Trevor Wilson www.rageaudio.com.au