HP27: lowest keyboard horizontal row not working

[isanchez]

Hi everybody,

I have an HP27 (Woodstock) in working condition.Yesterday I noticed that the “2” key did not work as it should, so I decided to clean the keyboard. I disassembled the calculator very carefully. I have done this hundreds of times.

After cleaning the keyboard and reassembled the calculator , all the lowest horizontal line of keys did not work at all, these are: “/”, “0”, “·” “SUM+”
(by the way, the “2” works now fine ;-D)

I tried again a coupe or three more times: disassembling, cleaning, assembling.

This morning I have tested the HP27 board in an HP25 and works fine.

I swapped the HP27 keyboard in with the HP25 calculator and still the lowest line of keys did not work at all, so it seems clear it is a problem with the keyboard.

Do you have any idea what could be this malfunction caused by? The continuity is checked in al (vertical)l lines, but the horizontal line sounds weird for me.


Thanks in advance,

Kind regards

Ignacio