That was my definition of inadequate. The fact that 3 of us here have
seen large quantities of the same units with the exact same problems bear
this out.
I'm sure we've all seen plenty of amplifiers with a whole ton of dust
inside that have been working hard for years.

I had a theory that because once repaired they tend not to come back,
this may point to either a manufacturing issue or dodgy batch of
Darlingtons (?)



Gareth.




Oh, BTW, can you confirm which way the fans run? Sucking air out the
cabinet or blowing it in?



Gareth.

I'd never really considered a dodgy batch of transistors. I'd always put it
down to the cooling becoming poor when the fan grille got clogged, leading
to the paste frying to dust, and the transistors then overheating with
little or no compensation from the flatpak transistor in contact with the
underside of the heatsink. I have always obtained my transistors for these
from Farnell, but I noticed last time I ordered a few weeks back, that the
price of them seems to have gone up quite a bit from what I remember them
being last time ...

You know, off the top of my head, I really can't remember if the fan sucks
or blows. I should have been able to tell you today, as the shop that I do a
lot of these for, primed me earlier in the week for one that was coming in
as an urgent repair, as the band had a gig Saturday night. It hasn't
arrived, so if it does turn up tomorrow (ha! - today now!), the repair cost
has doubled ... :-)

I seem to think that the fan sucks air into the cab, which is what causes
the clog at the grille, but could be wrong. Oh to be young again, with a
head that stores things with total recall :-\

Arfa