[time-nuts] HP 58503B PSU replacement

[Dr. David Kirkby]

On Wed, 14 Nov 2018, 18:14 Gerhard Hoffmann <dk4xp at arcor.de wrote:

>
>
> If more than one replacement unit does not work, then it is not
>
> improbable that the switcher needs a minimum load to start.
>

There is a minimum load specified on the 5 V rail, and someone wrote above
that the GPS receiver does not meet that requirement.

I tested my supply in the GPS receiver, but it may be worth having another
go while definitely meeting the load requirements.


>
> Also, a shorted capacitor can show excellent ESR.
>

Luckily I have a Peak ESR70 ESR/Capacitance meter.


> I once had a cycling power supply in a W&G TSA-2 spectrum analyzer.
>
> It delivered power for some seconds, and that was enough to trace
>
> a voltage to a faulty feedthrough capacitor. A DVM with enough digits
>
> helps a lot. Towards the short, the voltage sinks mV by mV.
>

One of the problems with this PSU is a lot of components are glued
together. It is almost impossible to see if some tracks belong to a
capacitor or not.

The board layout leaves a lot to be desired. There are components mounted
about 45 degrees to the board to fit them in.

>
>
> regards, Gerhard..