[time-nuts] LPRO-101 BITE (~lock) Signal Always Low

[Wayne Holder]

I have a surplus LPRO-101 that seems to power up OK.  The power draw starts
at 1.7 Amps and then, after a few minutes, drops down to 600 mA, or so and,
after this startup, the output shows a 10.000 MHz signal thats 's
accurately as I can measure it.  The lamp voltage is 6.2 volts, which seems
within spec.  However, the BITE signal that's supposed to indicate lock
with a LOW level is always LOW and never changes.  The docs say that BITE
signal should start at a HIGH level to indicate no lock and then drop to a
LOW when lock is obtained.  So, this behavior seems all wrong.

I opened the case and observed the purple glow of the lamp and probed
around IC U401, which buffers the BITE signal, and saw the same signal LOW
level.  U401 is getting 5 volt power and the inputs to the AND gate used as
a buffer for the BITE signal match what I'd expect.  But, lacking a proper
schematic, I'm not sure how to trace this back to the problem.  Has anyone
ever seen a symptom like this with an LPRO101?

Wayne