Does anybody know anything about this C12 PSU ?

[Rob Flinn]

Just wondering if anybody has come across this particular C12 PSU ?

I have it on the bench & seem to have some eissues with the bias voltage, which sits at around 4.8v therefore shutting the valve down.

There is some sort of ramp circuit when it powers up.  Lemo connector to mic.  Seems to have control over B+ & heater voltage but not the bias.

 

[Rob Flinn]

Here's a pic of the track side of the pcb.  The only marking is RNT.