Help with Oltronix B40-1 pwr.supply

[Stein-Olav Lund]

I am fixing an old, quality-built Swedish lab power supply from about 1960..
I have the schem. for C40-1, but this one has an older circuit which
includes two neon stabiliser tubes and a built-in high voltage supply
for them (seems they didn't trust semiconductor VR's well enough back
then...)
Does anyone have any info about this circuit?


Stein-Olav Lund

 

[Stein-Olav Lund]

Stein-Olav Lund wrote:

I am fixing an old, quality-built Swedish lab power supply from about
1960..
I have the schem. for C40-1, but this one has an older circuit which
includes two neon stabiliser tubes and a built-in high voltage supply
for them (seems they didn't trust semiconductor VR's well enough back
then...)
Does anyone have any info about this circuit?

Forgot to describe the fault...
The output voltage for the C40-1 is adjustable down to zero, and I'm
pretty sure it should be so with this model also. I can only get down to
about 12V.
There are three (!) auxiliary power supplies in it, they seem to give
reasonably correct voltages. All semiconductors test okay with several
test methods (have tried other Ge power transistors, but same result,
the ADZ12 and like in TO36 can have high leakage current)
Even a 'new' Si PNP transistor gives the same behaviour.
Does anyone have a schematic for it, I have tried a search on the net in
vain.

Stein-Olav Lund