Hi Tom, The A8 Reference buffer also feeds the 10MHz clock for A9/processor board. I would first check A8, C17 and C18. Regards Guido > > On 17 jul 2025 at 18:38, Tom Verbeure via time-nuts <time-nuts@lists.febo.com> wrote: > > > > > > On Jul 15, 2025, at 5:00 PM, Magnus Danielson via time-nuts <time-nuts@lists.febo.com> wrote: > > > > Hi, > >> > >> Service powersupply. Should be relatively trivial. > > I removed all the boards except the power supply controller and the 15V was now present. Unfortunately… > > I then reinserted boards one by one to find the one that’s pulling the 15V down: it’s the 10MHz detector board that sits next to the OCXO power supply board. All other boards are plugged in. > > I would expect that with only this board removed, the CPU should be up and running and maybe displaying an error message? But that’s not the case: except for a 4 status LEDs, the display stays dark. > > Does anyone know if that’s expected? > > The 10 MHz detection board is not connected to the CPU bus, so the lack of it shouldn’t result in a bus hang. > > Tom > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe send an email to time-nuts-leave@lists.febo.com