On Tue, 21 Mar 2017 08:34:08 -0700, John Robertson wrote:

You may be able to find your BF472s sourced from India:

http://www.diyaudio.com/forums/solid...f471-472-good-
replacement-2sa1381-2sc3503.html

I did a search and no BF numbers showed up, however they did manufacture
the device recently according to the referenced PDF. You may have luck
tracing the part through CDLI's distribution network. It never hurts to
ask!

Is Indian stuff kosher? Like others here I've had big problems with fake
semis from the far east; voltage regs in particular.


I would also check T710 (BF458) and T707 (BF199) as well though before
ordering anything. A simple gain test should suffice. Try to find a
reliable source for these transistors, there are a lot of Chinese (etc.)
fakes out there!

Oh yes, see above!

Have you upgraded the electrolytic capacitors in your scope? They are
most likely well past their Best-Before date!

They were *all* totally fine! I mean I'm sure they're not as they were
when new, but none of us are. ;-) The fault with that scope (if it's the
one I'm thinking of) turned out to be a diode in the SMPS section that
someone had subbed with an inferior part. It needed a fast recovery diode
and someone had stuck in the first spare diode the could find I'd
imagine. It would have worked fine at 50Hz but this was 20kHz. One of the
guys who posts here spotted it from a photo I posted!