In article , sck0006 wrote:

I have a Power/Mate BPA-10E with issues. It is adjustable from
~2.5VDC to ~13VDC (The panel meter is 0-10VDC, so I assume that that's
what it should be adjustable throughout). I'm checking the output
with a calibrated Fluke 87, so it's not just that the meter needle is
offset or something of that nature.
..
..
Any idea what these original transistors are? Via diode test they are
NPN devices. This supply is 10V 10A, linear, so assuming they
dissipate maximum voltage of 10V, maximum current of 2.5A each, they
are 25W or so (I know, very brutal calculations, please don't tear me
apart for it). Should common new transistors such as 2n3055's or
something along that line work? Any idea what the originals are, what
their ratings are?

Steve-

Not being familiar with that power supply, it isn't clear what your
problem is. Exactly what is it that is "offset by ~2.5V"? Does the
built-in meter read something different from your Fluke? If the panel
meter agrees with your Fluke, then it would appear to be working properly.

Power dissipated by the transistors is computed by voltage DROP, not
output voltage. Measure the voltage between collector and emitter while
the supply is delivering rated current, multiply by rated current and
divide by the number of transistors.

It is possible that the maximum current rating only applies at maximum
output voltage. I assume you have checked the manufacturer's web site for
data.

Without a cross reference to the Power/Mate proprietary part numbers, the
best you can do is guess. The 2N3055 is as good a guess as any.

Fred