[time-nuts] Re: 5370A repair

[Tom Verbeure]

> On Jul 15, 2025, at 5:00 PM, Magnus Danielson via time-nuts <time-nuts at 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