Wanted: Hp Display Tube 5083-1551

[Tony Duell]

On Sun, Jun 20, 2021 at 11:23 AM Holm Tiffe via cctalk
<cctalk at classiccmp.org> wrote:
>
> hi all,
> a friend of mine (Hartmut) is restoring desktop- and pocketcaluculators
> as a hobby. Lately he got an HP9100B on his desk with a bad display tube (the
> getters are white) but is otherwise in a good shape.
>
> Is here possibly someone that has such an display Tube to sell?

Those tubes are _very_ hard to find as a spare part. They are, of
course, electrostatically deflected and the deflection angle is a lot
larger than normal. This leads to poor linearity, which is why 'scope
tubes have a small deflection angle, but of course that doesn't matter
for a digit display.

Just about the only source is another HP9100 (it's the same tube in
the -A and -B models) but of course it is not a good idea to raid a
repairable machine for the CRT.

And a word of warning. If the tube has received enough force to crack
the envelope ( hence air gets in and the getter oxidises to white)
it's likely the glass rods that support the electrodes have cracked
too. This leads to shorts between the deflection plates and the
high-voltage anode. If this has happened and the machine has been
powered up like that, then there are very likely to be blown
transistors and diodes all over the place.

-tony



>
> Kind Regards from Germany,
>
> Holm
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