On Tue, 21 Mar 2006 16:13:47 GMT, "Dave"
wrote:

I've identified a bad transistor in the power supply of an audio component,
circa 1981. It's a 2SB527 PNP transistor... I had a bit of a look around on
the net and didn't find any quick easy sources. This transistor's sole
function is to convert -26VDC coming off one side of a bridge rectifier
to -13 volts. It's wired up as follows, and I apologize for not being more
skilled in ascii art or I'd try to draw it.

The collector is the -26VDC input. It is connected to ground via a 100uF
cap.
The emitter is the -13VDC output. It is connected to ground via a 10uF cap.
The base is connected to a series 470-ohm resistor, then a parallel 10uF cap
(to ground), then a parallel zener diode (to ground), then a 5.6K-ohm
resistor, then to the collector.

My question is thus: if my downstream components can get by with -15VDC,
can I just substitute a 7915 15VDC negative voltage regulator? There are no
feedback connections from any other part of my circuit to this transistor,
it's output voltage should not vary under normal conditions. And, by freak
coincidence, the pinout of the regulator matches my circuit perfectly, it'd
be a straight swap and removing a couple of resistors. And perhaps most
importantly, I have one.



We used to sub a 2sb633 which cost about a U.S. dollar. Chuck