In article d%AUf.955$B_1.194@edtnps89, "Dave" wrote:

"Dave" wrote in message
news:%CVTf.6013$J43.2877@edtnps90...
I've identified a bad transistor in the power supply of an audio
component,
circa 1981.

Well I went with a TIP42C, over-rated (6A vs. the 0.8A I am replacing AND
that's probably over-engineered) but available locally. I don't have any
mica insulators or plastic screws and they are an hour drive (or $15
shipping) away.

I still don't know where you got that spec. What was the manufacturer of that
obsolete unit.

Thanks for everyone's help, I learned a great deal. BTW, I threw the new
PNP into my DMM's transistor testor and it came up with an hFE of 390. I am
thinking that this is a fairly useless number other than to show that the
transistor is functional as the hFE measurement will vary greatly with input
current. Wonder what the old one would weigh in at? Interestingly checking
the old transistor with a multimeter showed perfectly normal behavior, B-E
conducted one way only, B-C conducted one way only, C-E did not conduct.
But it didn't work in my transistor tester, came up 000 for hFE.

Again, thanks for the assistance.

You really need sets of curves to get a real indication of things.
I have mostly tested them out with an analog ohmeter, my favorite.
Sometimes you will see extra leakage on CE or other terminals
when they are bad. I have not tested a bad unit with the diode
test function, which should indicate some voltage drop across CE.
greg