Hello all,
I've a 1111C OCXO (inside a Symmetricom 5045A that is inside an
Oscilloquartz OSA 5585) that refuses to start. It seems that one voltage
regulator is not operating, with only 2V at its output while it should
have (I think...) around 12V. I've partially analyzed the circuit, and
it is nothing from other world: a 6.9V reference diode, driving an
operational amplifier, driving a NPN transistor. But the 6.9V reference
diode is biased from the regulator output, so... if the regulator does
not provide output, the zener is not biased, and then... the regulator
does not provide output. So it must be some kind of start-up circuit,
that makes the transistor to conduct a bit, or to bias the diode, when
power is applied.
I've been looking around, but not found it yet. I have make a quick test
by placing a 6k8 resistor between the collector and the base of the
transistor to make it conduct, and then the regulator starts, provides
adequate output (12.5V), and also the 5MHz output appears.
Any idea is welcome :)
Best regards,
Javier
_______________________________________________
time-nuts mailing list -- [email protected]
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
