[time-nuts] Restoring a Datum PRS-50

[Clint Jay]

OK, not quite so lucky, the main board now has all new tantalums fitted and
was in excellent condition after a little soot removal.

However, the bad news, the DC-DC converter is quite badly damaged, there
are some broken tracks within the inner layers of the PCB, I think this is
because the thru-hole plating has been damaged in a repair attempt at some
point in the past, does any one have a schematic, a spare (not necessarily
working) board I could borrow to draw the schematic from or, perhaps even
better, a cheap, untouched replacement PSU, working or not?



On Fri, 3 May 2019 at 19:29, Clint Jay <cjaysharp at gmail.com> wrote:

> I've just laid my hands on a Datum PRS-50 Cesium reference which 'released
> the magic smoke'.
> A common problem with these is the capacitors in the main PSU but these
> have already been replaced by the previous owner.
>
> Unfortunately when he powered it up there was smoke released.
>
> I *think* I've located the source of the smoke and it looks like I may
> have been very lucky indeed as the only burned part I can find is a 1uF
> tantalum capacitor across a power rail on the main 'logic' board so I've
> ordered replacements for all of the tantalums I can find, including the 2
> 47uF ones near the CS6158 Line drivers and will replace them all before I
> attempt to power it up fully.
>
> None of the SMD work or clean up holds any fear for me with the exception
> of the single 1uF tantalum that's in the conformally coated section of the
> board near the Burr Brown PCM54HP, the remoival and replacement should be
> fine but I am worried I might disturb something critical or upset some
> finely tuned parameter?
>
> I'm also wondering about testing the main PSU 'out of circuit', I can load
> it all up, that's fairly easy but is there any reference to what voltages
> it generates and if there are any test points?
>
> --
> Clint. M0UAW IO83
>
> *No trees were harmed in the sending of this mail. However, a large number
> of electrons were greatly inconvenienced.*
>
>

-- 
Clint. M0UAW IO83

*No trees were harmed in the sending of this mail. However, a large number
of electrons were greatly inconvenienced.*