[time-nuts] HP-5245L display...

[paul swed]

Oh thats the next very brave step I may take. Into the black box. I know it
uses neons and they are still available if the ones I have won't fit. I am
concerned the real problem may be the photo resistors. But that said I will
save that self abuse for another day.
Always good to have  "repairs neon state logic" on the resume.
Maybe plasma state logic sounds better.

On Sat, Jan 9, 2010 at 4:32 PM, Burt I. Weiner <biwa at att.net> wrote:

> 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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