[time-nuts] HP 5245L Question

[g4gjl at btopenworld.com]

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