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Re: Peavey XR 886, 1997, mixer amp

This is the amp in question

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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

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

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Reply to
N_Cook
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I think that the worst part of that desgn IIRC is that the board is mounted inverted with the sinks beneath, thus any heat which tried to escape by convection has to pass through the pcb, heating the other components. Am I correct in that assumption?

Ron

Reply to
Ron(UK)

amp

the

flow

contains

either

or 2

outlet

etc

the

much

The heatsink is fitted onto the pcb that caries nothing on that area but holds a lot of ceramic W/W seen either side on the pic, usefully, I suppose, in the airflow.

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

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Reply to
N_Cook

A better pic , without yellow ring is now at

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-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

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Reply to
N_Cook

That ancient Peavey transformer might be hotter (thermally! not wattagely!) on 50hz than on 60hz, and class AB amps dissipate worst case power at about 1/3rd max power.... its where the load line runs right across the hyperbola on the IV curve... and if the voltage in the club sags when the drink cooler compressor turns on, its a perfect storm of overheat factors.

Reply to
BobG

Voltages in the UK don`t generally sag much if at all

Ron

Reply to
Ron(UK)

=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D Is that in percent or in volts? I've glanced at the power line monitor during the end of a song and seen 105V... should be 120, but with lights and air conditioners and everything else, 115 is more like the nominal. So that 10% low.

Reply to
BobG

Our mains supply is 240 volts

Reply to
Ron(UK)

AFAIK the lowest legal voltage the electricity company can supply in the UK is 10% down (from 240) which is 216v, the highest legal voltage is 254v, less that 6% high. Suffice to say you won't normally get those kind of variations at the mains intake at the venue.

I don't know how much voltage drop you might experience due to the clubs wiring before it was deemed unsafe or illegal though.

Gareth.

Reply to
gareth magennis

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