Ron wrote in message
...
On 04/12/2011 21:19, N_Cook wrote:
This is one of my repair briefs that may well be consistent with your
query
symptoms, causation would seem to be PbF or electrolytic intermittent
punch
through


Well that's an actual component failure, the fault I`m on about is
intermittent and very common. It doesn't seem to be dry joint or heat
related, sometimes they come on then go off, sometimes they fail to
produce sound even tho the meters show a signal.

Switching of and on again generally restores operation. It's become a
common fault and a shame because the units are otherwise very useful for
small gigs and if not for this lack of trustworthiness would be
lucrative for hire purposes.

I imagine that the typical case of output device failure might be caused
by the unit being thrashed beyond its design limits (as so often happens)

Ron

I think I've repaired 3 different 300 Stagepas. Each one dealt with the
blown amp and while in there, drilled open those tiny inlet holes and
propped open the outlet vent. None of them have returned so may or may not
be relevant. One of them the smaller fan had stopped functioning so probably
contributory. One of them the owner had noticed the outlet air was hotter
than usual (same set and useage as normal),
Later versions had more holes in the outlet vent which suggests a heat flow
problem , then after that perhaps PbF problems. I'll have a look at the
thermistor/thermal protection area of the schematic some time