[time-nuts] Questions about HP 5370B

[J. L. Trantham, M. D.]

There is a good trouble-shooting tree in the 10811 manual that addresses
these issues.

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
failures.

Joe

-----Original Message-----
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.

Dan





_______________________________________________
time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.