[time-nuts] HP-5245L display...
Burt I. Weiner
biwa at att.net
Sat Jan 9 21:32:21 UTC 2010
Peter,
The driver lamps in the display magic black boxes consist of neon
type bulbs. Like all neon devices, over time they become
flaky. Many years ago I had success in replacing some of the neon
lamps in one of my displays, which solved the problem - for a few
years. A side benefit was that I learned some new words and even
invented a few even newer ones!
I'd also thought about replacing the original display portions of the
boards. As I recall, there was an issue with the way the dividers
and display works and I don't believe they work on decades. I may be
wrong on that, but that's what's stuck in the krell of my memory. If
you should wind up replacing the nixies and their drivers I would be
very interested in what you do. I think the 5245L counters were a class act.
Burt, K6OQK
>Subject: [time-nuts] HP 5245L Question
>
>
>I read the recent comments on the HP5245L with interest. I have
>several of these excellent instruments and recently used one in
>anger, to repair a 20GHz Signal Generator (HP 70000 Series) for my
>employer, thus saving them circa ?10000.
>
>My question is, has anyone experienced the deterioration of the
>photo cells, another early semiconductor device with somewhat less
>than a forty years life expectancy? These seem to fail randomly, and
>I guess it is also a hygroscopic problem.
>I wondered about replacing nixie tubes and associated drivers with 7
>segment LEDs in one of my (already hacked) units, to make it more
>reliable. I would use the BCD to drive the display, thus requiring a
>new interface board to be designed. I wonder if anyone else has
>considered such a radical remedy to the failing photocell problem?
>
> In case anyone is wondering 'WHY BOTHER?', my defence is that I
> too have an extensive collection of the plug ins, extending the
> usefulness of the basic instrument way beyond my budget for more
> modern equivalent instruments.
>
>Hope this question is not considered too far off topic for this forum.
>
>Peter Worrall
>G4GJL
>London
Burt I. Weiner Associates
Broadcast Technical Services
Glendale, California U.S.A.
biwa at att.net
K6OQK
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