This is the amp in question
http://home.graffiti.net/diverse:gra...net/peavey.jpg
Yellow ring stands in for the 4 inch fan removed (position marked with
Fs )along with metal sheet that encloses the heatsink. The view of this amp
is upside down as the fan is at the base. So drawing air horizonatally
theough a "designed" 5/8 inch space under the amp. Air then goes through the
1 in of fan vertically and then has to sharply divert horizontally to flow
either way through the 3 ducts in each direction. The central duct contains
no active ducts and as far as I can see only interferes with air flow as
they are right up against the fan housing. Air then vents mainly at either
end when the metal closure in place with not enough space to add a fan or 2
at those points and nowhere near the mains transformer and main air outlet
vent . A lot of venting must go up and out the mixer pannel slider holes etc
as well. The 2 TO3 mounted thermal switches are marked S and restrict the
air flow through the uppermost duct in the pic, the leads and spades as much
as the switch body


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Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/