At work I repair some ballasts that use 2 * TIP41's, these die on a=20
regular basis often burning a nice hole in the PCB at the same time as=20
disintegrating.

After trying catch diodes (didn't work), I experimented with replacing=20
TIP41's with BUJ 302a from NXP, these have a breakdown voltage of around=20
1kv.

The other day one of these repaired ones died, but one BUJ died O/C between=
=20
all three pins, and the other O/C between CE and S/C between BE. I've not=20
seen a transistor used in transformer multivibrator circuit fail O/C=20
before. Is it possible NXP have some form of internal resistor or perhaps=20
this is a result of some inherent manufacturing technique of high breakdown=
=20
transistors?

Obviously failing open circuit is much much safer than short circuit.

Colin
--
cdb,   6/01/2012
=20
--




colin@btech-online.co.uk

--=20
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