[time-nuts] HP5328A repair experience
magnus at rubidium.dyndns.org
Mon Sep 7 21:00:56 UTC 2009
Some time back I was given a HP5328A that was working well, but started
eating fuses. Fortunatly all manuals came with it.
It does eat fuses, but I failed to detect why at first. I went down some
dead ends debug-wise, just to show that I am a bit rusty, but time to
polish the rust of then...
In the end, the negative rail cap had shorted out. Nothing obviously
wrong with that side. The way that the PCB trails work, there is a
separate PCB trail to the negative side of that cap, and that had bruned
straight off so the rest of the negative side was almost working.
Replacing both 4500 uF 35 VDC caps by RIFA 6800 uF 40 VDC PEH200 caps
(works perfect as drop-in replacement as terminal screws and body size
matches very well).
Power up and everything checks out fine. Just... works.
I have option 020 and 040 in mine, so it will do the funky jittered
clock interpolation on averaging while achieving 10 ns singel-shot
resolution from it's 100 MHz oscillator compared to 100 ns from the
standard 10 MHz counting clock. I actually have a couple of 010 option
boards with 10811 oscillators on them.
While it is not by any means my best counter, it's nice to see it
So, hopefull someone apprechiate this little notice. Call it a distant
echo from the past if you so wish.
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