Bob, The thermal fuse is inside the OCXO which is inside the outer oven. There was a recent (past week or so) thread on this list about a thermal fuse failure including pictures of the inside where the fuse is located. This, however, was for the 'non' wrapped version of the 10811. The problem will be getting past the outer oven. I've never tried that though I have replaced the thermal fuse on the 'non' wrapped 10811. That was really straight forward.
I don't recall seeing a manual specifically for the 'wrapped' version of the 10811 but the manual for the 'non' wrapped version is available on the internet. I think one is on Didier's site. The trouble shooting guide is very helpful in finding out if the thermal fuse is the problem. Just measure the heater circuit current for the inner oven. If zero, the thermal fuse is the place to start. The outer oven, though, I think is separate. If your Z3801A is used indoors, I suspect the outer oven is probably not needed. Good luck. Joe -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Robert Benward Sent: Tuesday, November 01, 2011 8:00 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Z3801 EFC error Joe, Good guess. It's a 10811 with an additional oven wrapped around it for better thermal control. I'll check it in a couple days when I get home. Is this thermal fuse on the outside? Anyone have a schematic of this unit? Bob ----- Original Message ----- From: "J. L. Trantham" <[email protected]> To: "'Discussion of precise time and frequency measurement'" <[email protected]> Sent: Tuesday, November 01, 2011 12:21 AM Subject: Re: [time-nuts] Z3801 EFC error >I think it uses a 10811 OCXO. See if it is warm. If not, perhaps the > 'thermal fuse'? > > Joe > > -----Original Message----- > From: [email protected] [mailto:[email protected]] On > Behalf Of Bob > Sent: Monday, October 31, 2011 11:17 PM > To: [email protected] > Subject: [time-nuts] Z3801 EFC error > > Hi, > My Z3801 just crapped out. It seems that the DAC has ramped up to the > rails, 1048560, and I'm getting an EFC fault. Any tips before I open the > unit and start poking around? The oscillator is running and pretty close > to > 10MHz, I don't have any reference accurate enough to check it. Any trends > here, is it the EFC in the oscillator or is it the DAC and following > amplifiers? > > Thanks, Bob > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > > > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
