|Re: A few questions to ask. Then we can talk about it as invasive key fixes are difficult on the 48|
Message #4 Posted by Geoff Quickfall on 22 Apr 2009, 11:02 p.m.,
in response to message #3 by Harold A Climer
There are three ways to lose the 'feel' of the keys. Especially ones used as frequently as the F keys on a 48 that has dedicated F functions; i.e. the VAR menu with assigned folders and variables
The construction of the keyboard includes a domed contact. As the key is pressed into the apex of the dome, the dome deforms toward the keyboard contact completing the circuit and giving the resounding click.
The setup is similar to the following HP 45 keyboard with the exception that the raised portion is domed not rectangular ( I currently don't have a picture of the keyboard layout for a 48):
With consecutive use this system will fail over time.
The calculator is held together by plastic rivets. Actually plastic inserts into plastic tubes which are then glued under pressure. The upper rivets, depending how well they were formed at construction may give. Especially under duress such as a drop or extensive use. As the rivets loosen, the distance the key has to move to engage the 'dome' increases and the deformation of the dome may have a reduced click to it.
The sticky residue problem. This will entail the cleaning of the keyboard, non-envasively. This can be done by removing the batteries, battery hatch and memory cards as well as the memory card hatch.
Without seeing your calculator and assuming it is not the sticky residue problem or rivet problem; it would seem that it metal fatigue of the dome contact system.
Not much can be done for that other than 'Fix that Calc'. If the cleaning does not improve the feel, try the following:
1. Place the calc on a flat surface.
2. Gently apply finger pressure at the edges of the calculator
corresponding to the row with the F keys
3. while applying pressure, press the keys with your free hand
and see if the keys respond normally.
This would indicate that the rivets may be at fault. Both the dome fatigue and rivet would require surgery unfortunately.