[time-nuts] Questions about HP 5370B
J. L. Trantham, M. D.
jltran at att.net
Tue Sep 14 23:15:59 UTC 2010
There is a good trouble-shooting tree in the 10811 manual that addresses
I had a 10811 where the oven would not come on. I found the thermal fuse
open and even ordered the replacement part from HP. It was only a couple
bucks IIRC. I also found some close ones for only a few pennies.
Once replaced, I went through the trouble-shooting tree only to discover all
things working correctly. It has done fine since with no further fuse
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]On
Behalf Of Dan Rae
Sent: Tuesday, September 14, 2010 10:28 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Questions about HP 5370B
On 9/14/2010 1:23 AM, John Miles wrote:
>> As Bruce suggests, you'll want to peek inside to see that you
>> really do have
>> a 10811 oscillator. If so, then it sounds like the thermal fuse
>> (F1, inside
>> the 10811) might be open.
> Just short it out, or if you like, put in an NTE part with a similar temp
> rating. It serves little or no useful purpose.
> -- john, KE5FX
I hate to disagree with John who knows a heck of lot more than I ever
will, but in this case it will protect the oven from cooking up if the
control circuit fails with the heater full on, which can happen.
I did have a 5370B with a 10811 that had a bad thermistor in it as well
as an open fuse. I'd guess that's why -hp- fitted it.
But yes, the thermal fuses can and do fail open for no good reason,
and it sounds like this has happened here, but I would not recommend
shorting it out permanently.
time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to
and follow the instructions there.
More information about the time-nuts