11 Feb
2014
11 Feb
'14
8:52 p.m.
Hi,
as my first post here I would like to ask a question about a DEC
correspondent terminal with a broken power supply.
due to a shorted capacitor in the output stage, a whole train of parts
has failed, including some diodes, a coil and the main switching
transistor in TO-3 case. that is the part with a strange partnumber:
A8250
151278200
I suspect that the 8250 is a manufacturing date and the long number a
internal DEC number, but what sould be put in its place. i was thinking
about just using a irf840 mosfet, but i have no idea as if this would work.
Do you have any reason to think it's a MOSFET? Without seeign the unit, I
would have guessed at an NPN bipolar trasnsistor.
Chopper transistors afe often critical, and what seems a though it should
work on paper doesn't work in the unit. And of courswe when your BU208 or
whatever blows up, youu don't know if it's because it wasn't suitable or
if it's becuase there is anther fault somewhere.
-tony