The Museum of HP Calculators

HP Forum Archive 15

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opening Woodstock calculators
Message #1 Posted by Matthias Wehrli on 22 Mar 2006, 11:43 a.m.

I need some advice (text, pictures, ..) how to open these sort of calculators.. not the simplest thing, but to repair a HP-29C or HP-27A it is worth that time ;)


Re: opening Woodstock calculators
Message #2 Posted by Bernhard on 22 Mar 2006, 6:28 p.m.,
in response to message #1 by Matthias Wehrli

The procedure I use on the HP21...HP29C series:

Remove battery. Pull out the two topmost rubber feets (i.e. using a dentist's hook). Remove the two screws now visible. Gently apply some pressure to the charger contacts until the keyboard comes out of the shell by about 2...3 mm. Now the trick: turn the unit upside down and stick a thumb's fingernail between the keyboard and the shell near the point (*) on the label with "Hewlett * Packard". There should be a snapping sound and the keyboard now is free from the shell. The whole assembly (keyboard + electronics) now is loose and can be removed from the shell (gently, gently, remember those battery contacts that protrude into the battery compartment).

During reassembly, it is important to snap keyboard + electronics plugged together into the shell. If you put in the electronics first and then try to snap the keyboard in, some of the connector spikes most likely will be bent.

(No warranty implied and no liability taken especially for broken fingernails. Note that a metal blade etc. might damage the plastic).

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