On 04/12/2011 13:13, N_Cook wrote:
wrote in message
...
Greetings folks

Has anyone yet got to the bottom of the StagePass300 intermittent sound
problem which seems to be endemic with the units these days.

Sound cuts out intermittently, although the leds continue showing a
signal which returns if the unit is switched off and on again. There
doesn't seem to be a mechanical cause such as dry joints etc. as tapping
the unit makes no difference. It seems to be possibly a problem with the
protection circuits.

Ron


I've only ever seen blown channels. Beware antiphase outputs . Increase the
fan apertures while in there. Schematic as .rar probably on eservice.com ,
opens to
Yamaha-Stagepas300 pwrmix.part1
then pdf
I would drill open some of those tiny vent holes and open up the outlet side
of the "main " fan and see how it fares after that


It's not a heat issue, these units can fail on switch on or after any
indeterminate period of time, sometimes they don't fail at all for weeks
then fail several times in one gig.

Yamaha are quite aware that there is a problem yet don't seem to want to
share.

Blown channels are often caused by using metal bodied right angle jacks
in the mixer unit. If two plug bodies touch, or one touches the metal
handle it shorts out one of the amps.

Ron