The Museum of HP Calculators

HP Forum Archive 13

[ Return to Index | Top of Index ]

Pioneer keyboard (esp. HP-42S)
Message #1 Posted by Erik Ehrling (Sweden) on 17 Aug 2003, 7:48 a.m.

Hi all!

I have two keyboard problems with two of my HP-42S calcs.

1) On a USA built Rev A the LN key has become unresponsive. It works if I press it firmly but not with a light press (all other keys do).

2) On a Singapore built Rev B the STO key has a very annoying clicking sound. Sometimes the sound goes away if you press it two or three times, but it comes back if you have not pressed it for some time.

Is there anything I can try to fix these calcs? (Blowing them with compressed air? Cleaning them in a ultrasonic cleaner? Anything else?)

Best regards, Erik Ehrling (Sweden)

Re: Pioneer keyboard (esp. HP-42S)
Message #2 Posted by Randy Sloyer on 17 Aug 2003, 8:43 a.m.,
in response to message #1 by Erik Ehrling (Sweden)

Take the batteries out of both and give them several passes in distilled water in an ultrasonic cleaner. Ten minutes is usually enough on each pass. Stop midway through each cycle, take the unit out of the water and press each key several times. This changes the water inside each key dome area. Change the tank water after each 10 minute cleaning cycle. You might be temped to clean both at the same time, don't unless the cleaner is large enough to hold them without touching. The cases and bezels will develop wear marks should they touch.

When you've done two or three cycles, shake out all the water and let dry for two days in a warm place.

Unit 1 may clean up and be okay as the LN key gets low usage compared to the 0-9 and basic 4 (+-*/). If it was one of those keys, I wouldn't have a lot of hope. I've found the older USA and early Singapore units to develop this type of failure, it's due to the conductive material flaking off in the domed part of the switch.

Unit 2 will probably clean up fine, sounds like a spill of something got into the keyboard.

[ Return to Index | Top of Index ]

Go back to the main exhibit hall