On Sun, May 28, 2017 at 4:50 PM, Mattis Lind via cctalk <cctalk@classiccmp.org> wrote: > Hello! > > I recently received a HP9816 machine. The previous owner originally got the > machine without a keyboard but subsequently sourced a keyboard off ebay. > > Unfortunately this keyboard was not in the best shape. One key was stuck > and when taking it apart it was evident that it has taken a bath for quite > some time. At least the electronics around the space bar were quite > affected with corrosion. Luckily this keyboard is quite simple design with > only CMOS 4XXX IC, and better yet, Tony Duell has already reverse > engineered it (together with the rest of this little machine). Thanks a lot > Tony!
IIRC it's a very odd design electronically, in that the keyswitches are not wired as a matrix. Rather they are each wired between ground and an input of a 4051 multiplexer. I have no idea why it was done this way. > > But the stuck key appeared to be cause by the "plunger" (is that the > correct english word?) is slightly cracked in the corner. When the keytop > is inserted it is not sliding very well. > > I have not found a method of repairing it so I am asking the community if > there are anyone that has spare "plungers" for the HP9816 keyboard. I believe the same plungers were used on many other machines. I know for a fact that a VT52 keycap will fit an HP9816 keyboard, so the plunger is very likely to be the same as that machine. Other likely ones are VT100, early TRS80 model 1, TI99/4A, HP85 (etc). That may help you find a scrap keyboard to raid. -tony
