[time-nuts] HP 5065A Rb, false "integrator limit" error

[Stewart Cobb]

I have a HP 5065A which has been running happily undisturbed for more than
a year. Yesterday I noticed that the front panel "integrator limit" light
is on. As far as I can tell, it shouldn't be on.

On the meter, the "control" and "error" readings are both very close to
zero. The signal on the back panel "control" jack is also very close to
zero. Slight tweaking of the "osc fine adjust" control causes matching
slight variations in the control signal, both on the meter and the jack, as
one would expect. And the output frequency is stable like a good Rb lock.

So I think the integrator itself is working fine, and the integrator limit
error detector is broken. Has anyone seen this before? Any advice?

Related question: the widely available service manual for the 5065A is
dated 1979. My unit has a model date (first four digits of serial number)
about five years later than that. Does anyone have the update pages for the
manual, or a later dated manual?

Cheers!
--Stu