In article ,
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This morning, I stuck a 2SK526 in because I had one on hand and
the voltage specs looked suitable. The case size is larger than
I would have liked, but the pins lined up and [barely] fit the
PC board holes. It works so far, up thru 64KHz, which seems to be
where the scan recognition wants to give up, and this seems about
normal based on past experience. Nothing getting hot, so I plan
to play it awhile and if all goes well give it back to the user,
cross my fingers, and see what happens...

It was in before and had a blown horizontal drive transistor.
I remember at the time I thought the drive circuit configuration
looked like it should be a MOSFET, but it had a 2SD667. I had a
2SD438 on hand and it worked. But a couple weeks later it is
back, this time with shorted HOT.

So now I'm thinking that I don't know where this thing has been
and someone may have put in the wrong transistor before I got
ahold of it, and I still think the circuit looks like it wants
a MOSFET, so maybe it's not switching properly and the output
is spending too much time in the linear zone and overheating.