|Opening (and repairing) a halfnut|
Message #1 Posted by Vieira, Luiz C. (Brazil) on 25 May 2003, 8:33 p.m.
Hi, HP41 maniacs.
I'm opening an HP41CV halfnut because it has a problem I cannot repair without spreading its guts around: after a MEMORY LOST and SIZE 000, it gives me .END. REG 63 instead of .END. REG 319. I did not test regular memory modules (82106A) so far, but I'll do it later. I read in some posts (some time ago) that RAM chips are in the LCD assy, and I'm gonna open it. I'm scanning all intermediate images so far, and I found out two somewhat important facts:
1 - tactile sense in halfnuts is solely due to a thicker rubber sheet between the keyboard and the keys; parts used in both half- and fullnut keyboards, i.e., the metal caps, are essentially the same;
2 - based on the ones I have in hands, calculator's plastic case has the same geometry for both types, meaning you can remove the halfnut guts and build a complete fullnut in the same halfnut case. I removed the halfnut guts and tested a fullnut keyboard. Fits perfectly. (in fact, after testing, I could not identify which case was the original one except for a missing post in the fullnut's one)
I am now with a strange thinking: I have an HP41C's case and a fullunt's guts that acts like an HP41C. I'm tempted to keep the halfnut's guts as is and build it as an HP41C. And I'll have a genuine... O.K., O.K., a cheated HP41C fullnut. In any case, I'll open the LCD assy in order to check for the cause of the missing 256 registers. As the plastic rivets were untouched, it's definitely a problem to be solved instead of an original HP41C halfnut in an HP41CV's case.
As I have all images scanned and saved, I'm posting a new message.
Luiz C. Vieira - Brazil