I have a Z3801A GPSDO that has been running fine for well over 10 years. It recently lost the lock indication and I can't get it back! I did look at the work around to fix the problem with the outer oven controller getting confused and it did not fix my problem. However it did show that the outer oven was not powering on, even if I supplied the workaround pull up described. With 0v supplied the oven is supposed to be off and with +5V supplied the oven should be on. With the 5V applies the oven voltage is zero. I did notice that the resistors R112 and R113 near P2 on the top board seem odd. R112 looks to be soldered very poorly and R113 is missing completely! Does anyone have an opened up unit or the top board loose so they can let me know what R112 and R113 are supposed to look like? The schematic I have does not show R113. Appreciate it and any advice. When the unit failed it did seem as it was still in lock and on frequency but with no lock indicator. Cheers, Corby

That board appears to be identical to the one in my Z3805A. From top to bottom, those in-place resistors are labeled like his on my Z3805A board (happens to be out, for re-capping): - 1002 - 1783 - 1102 - 1001 - 1332 --Andrew -------------------------------- Andrew E. Kalman, Ph.D. On Thu, Aug 17, 2023 at 3:55 PM Corby Dawson via time-nuts < time-nuts@lists.febo.com> wrote: > I have a Z3801A GPSDO that has been running fine for well over 10 years. > It recently lost the lock indication and I can't get it back! I did look > at the work around to fix the problem with the outer oven controller > getting confused and it did not fix my problem. However it did show that > the outer oven was not powering on, even if I supplied the workaround > pull up described. With 0v supplied the oven is supposed to be off and > with +5V supplied the oven should be on. With the 5V applies the oven > voltage is zero. I did notice that the resistors R112 and R113 near P2 on > the top board seem odd. R112 looks to be soldered very poorly and R113 is > missing completely! Does anyone have an opened up unit or the top board > loose so they can let me know what R112 and R113 are supposed to look > like? The schematic I have does not show R113. Appreciate it and any > advice. When the unit failed it did seem as it was still in lock and on > frequency but with no lock indicator. > > Cheers, > > Corby_______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe send an email to time-nuts-leave@lists.febo.com