[time-nuts] Restoring a Datum PRS-50

[Clint Jay]

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have already been replaced by the previous owner.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

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