You may find it interesting and educational to open up the unit and repair it. You've got nothing to lose but time if it doesn't work out. I don't know if the Z3815 uses the same double-oven OCXO as the Z3801, which I have, and repaired many years ago. The problem is almost certainly inside the 11801 OCXO, which can have a number of possible failures in the oven circuitry. In mine, it turned out to be a bad opamp. It was complicated because of having to take apart the outer oven, then unsolder the 11801 case, then do fault-finding while all these pieces are still operational and hanging together by wiring, and then put it all back together properly. I found lots of info online about the innards, from back when the Z3801 first hit the salvage market and had lots of interest and activity. It's not much anymore, but the info is still out there and relevant. If you manage to go through all this and get it back up and running, it can give quite a sense of accomplishment. Ed

hello Ed, Morris is going to ship it my way, and I intend to go down the repair path like you described. No promises on how quick or not (if at all) this will bear fruit. But I do plan to document progress in pictures etc. Just, as you say, it is an interesting challenge in its own right. Wilko > On 14 May 2025, at 18:55, ed breya via time-nuts <time-nuts@lists.febo.com> wrote: > > You may find it interesting and educational to open up the unit and repair it. You've got nothing to lose but time if it doesn't work out. > > I don't know if the Z3815 uses the same double-oven OCXO as the Z3801, which I have, and repaired many years ago. The problem is almost certainly inside the 11801 OCXO, which can have a number of possible failures in the oven circuitry. In mine, it turned out to be a bad opamp. It was complicated because of having to take apart the outer oven, then unsolder the 11801 case, then do fault-finding while all these pieces are still operational and hanging together by wiring, and then put it all back together properly. > > I found lots of info online about the innards, from back when the Z3801 first hit the salvage market and had lots of interest and activity. It's not much anymore, but the info is still out there and relevant. > > If you manage to go through all this and get it back up and running, it can give quite a sense of accomplishment. > > Ed > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe send an email to time-nuts-leave@lists.febo.com