Phil Allison wrote:

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.


** Some pics for you:


1. QSC USA1300, after many years operating in a venue:

http://s10.postimg.org/6e3lpj3ft/qsc1.jpg

This amp has two similar PCBs, one inverted above the other.


2. Perreaux 6000B, used but still fairly clean.

http://www.audioheritage.org/vbullet...d=11796937 34


3. Perreaux 2150, in pristine condition (cos no fan), close spaced tracks visible.

http://people.physics.anu.edu.au/~am.../underside.jpg


4. Perreaux 8000C, front view in good condition.

http://www.audiocostruzioni.com/r_s/...ux%208000c.jpg

5. Perreaux 8000C, close parallel tracks visible in centre of each PCB.

http://www.audiocostruzioni.com/r_s/...dentro%202.jpg

This amp would be a sitting duck for the PCB "tracking" problem.



..... Phil