HP 9000/200 (9816S) keyboard knob repair

[Paul Berger (Canada)]

(06-12-2015 11:14 AM)Martin Hepperle Wrote:  I also thought of using an LED with a resistor, but then I decided to stick with the bulb. It is important that enough light is shed to the side of the bulb and an LED would concentrate its light more to the front, where it is not needed. The sideways emission is fed into two parallel "channels" to project two thin beams of light onto the rotating disk. The whole system looks very simular to the HP-85 tape drive speed control.
Maybe it works with an LED, but I would not be surprised if the light emission to the side is too weak.
The wheel can be tested in the BASIC editor environment or outside with an oscilloscope.

I have never looked inside this particular one but I have a rotary encoder from a 16500A that uses a punched metal disk with two tracks of holes different sizes. It appears to use LED light, but it appears there may be separate emitters for each track. The dial on my small keyboard works and I was tempted to swap the two, but it seems it may be easy to fix too.

(06-12-2015 11:14 AM)Martin Hepperle Wrote:  Unfortunately I only got a disk with the testing software, which can also be found on the HP Museums web site. I think this software needs the extra test assembly to connect some pins and to supply the right voltage levels.
I have not yet dug deep enough, but I hope that it should be possible to access the card's control registers etc. It would be nice to have the "CSUB Utility for BASIC" software, though, to create the corresponding functions in assembler in the Pascal environment and then make them avaiable to the BASIC environment.

I too am hunting for the CSUB software and documentation but it seems to be rare.

The documentation of the card in the manual 98640-90001 is quite good, it has a section on programming that gives you information on how to talk to the card, you can even do it from BASIC using direct I/O commands but it would not be very fast.

(06-12-2015 11:14 AM)Martin Hepperle Wrote:  Thank you for this tip, I have to see wheter I can find this connector here in Europe. However this seems to be a card edge connector - my card has pins...
Martin

Yes Mine has pins too, but even though this connector is designed to be an edge connector, it has the same connector pitch as the pins and fits snugly over the pins.