HI again

On 19 Jul 2006 14:33:22 -0700, "
wrote:

Thanx for the quick replies!
I just wanted to add that one of the TIP's heat up immensely in just
half a minute, while the other remains barely luke warm. I do not
recall which is which, but surely they should both heat up equally
(indicating an equal load)? In that case, I guess I should probably be
looking at the cold TIP and its MPS transistors.

As the whole thing is DC-coupled, a hot output transistor could well
be caused by problems in the biassing. Try replacing the diodes
(?again!) and put a car light bulb (as in stop-light bulb) in-line
with both power rails. This will limit the current, and, with a bit of
luck, will give you time to do some fault-finding. At a rough guess,
the bulb in the line that lights up is associated with the transistor
that's failed.....

Give it a try - but be careful - 50V dc = a fair bit of 'energy'...

Regards
Adrian