[time-nuts] Failed HP 58503A VFD Segments

[Stan]

Hi all,

 

I have an HP 58503A Option 001 GPSDO that has been running faithfully for
many years. Yesterday I noticed that the same segment in all of the
14-segment display digits is not illuminating. It's the left lower vertical
segment ("E" segment). The 58503A is otherwise functioning normally, so I
believe it's either a segment driver or possibly a marginal solder joint
that has failed.

 

Before I tear into it, does anyone have hints on how best to troubleshoot
this? Are any schematics available? Finally, does anyone know what is used
to drive the segments and if the part(s) is/are still available, assuming it
turns out to be more involved than a failed solder joint?

 

Thanks,

Stan