HP 9000/200 (9816S) keyboard knob repair

[Martin Hepperle]

Hello,

recently I obtained a HP 9000/216 box with a big and heavy "Nimitz" keyboard. Like the smaller keyboards this has a nifty rotary knob which should control the cursor movement.
While I got the (German) keyboard to work the knob does not work.
After dismantling I found that the small lamp inside has burnt out.
I guess this is a similar setup as on the HP 85 tape drive and other HP desktop machines.
When powering the knob assembly with 5 V I measure 4.4 V across the (broken) lamp.
Before hunting for a replacement I would like to know whether someone has recommendations for this lamp or whether may even has it replaced by a LED-Resistor combination. Not sure whether this works, as the light should be emitted to the side and not to the front. Are there any other specific requirements concerning this lamp?
Currently I am inclined to search for a 6V bulb (3.2mm diameter) with wires as a replacement. Any other comments?

Besides this I am also looking for the cover plate and external PCB with screw terminals for the 98640A A/D converter (98640A-38). My machine came with this A/D converter board but the terminal end is missing.

Thank you,
Martin





Missing terminal block with cover plate ans thumb screws (photo stolen from HP-Museum):