Hi A little guess work:
Over a 10 year period something like one in 1,000 to 1 in 10,000 10811's fail. Of those, less than 1 in 1,000 are controller run away. Of the controller run away's 1 in 10 might be stopped by the thermal fuse. That puts you at a 1 in 1,000,000 to 1 in 10,000,000 chance of the fuse doing you any good. The 10811 sells for $125 any day of the week on the e place. If you are paying more than a tenth of a cent for the thermal fuse, it's wasted money. I doubt any of my ratios are on the low side.... Bob On Sep 14, 2010, at 7:15 PM, "J. L. Trantham, M. D." <jlt...@att.net> wrote: > 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-boun...@febo.com [mailto:time-nuts-boun...@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@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.