12C defective keyboard

[Zeca]

My tribute to the following suggestion found via google.

In my case the key "point" was working badly in a 12C (at the same time, there was no "click" when pressed). I followed the suggestion, opened the calculator and inserted a 3M double sided tape (circa 1 mm thick) on the back of the circuit board, near the defective key. After re-assembling the back cover the key was working again, with the traditional "click". Tips for disassembling (calculator with code starting with 4CY, 2 coin batteries): (1) Remove pads and the 4 screws under them. (2) Remove 2 more screws that you get access to when you open the battery compartment. (3) With a screwdriver separate the back cover from the calculator body. Be care to locate and preserve the two small springs that are used to guarantee electric contact between the circuit board and the back cover.
Insert a 3M double sided tape as mentioned above. Re-assembly the unit. The display will show an error, just turn-off and on again. Good luck.

Original post:
Re: 12C has keyboard problems, too
Message #3 Posted by Paulo MO on 10 Feb 2012, 3:45 a.m.,
in response to message #1 by Eric Rechlin
Some 5 months ago, I got a 12c+ from you (4CY11705LP). Bad ENTER key, bad "1" key, unsatisfying keyboard overall.

In another thread on this forum, some three months ago, we seem to have reached the empirical conclusion that calculators from 4CY have lower quality keyboards than calculators from the other factory (CNA). They can easily be recognized by a slightly different key font, and, notably, by the uncommonly large "%" key sign see here and here .

In my case, after many contacts and much frustration with an incredibly inefficient HP costumer service (Brasil), I decided to open the calculator. It turns out that the circuit board was not sufficiently pressed down by the heat stakes. I thus introduced a felt pad on the "bad key" region, so that the back panel would slightly push the board down. Both keys are now working fine. It still is an overall lower quality keyboard, though :-(

The 15 LEs seem to be produced only on the CNA factory. That is probably why the general feel of their keyboard is always good. But, as we all know, problems with particular keys exist there, also.

Paulo

Edited: 10 Feb 2012, 3:54 a.m.