|Re: Repair for HP 41CX|
Message #5 Posted by Vieira, Luiz C. (Brazil) on 29 Jan 2003, 8:45 p.m.,
in response to message #3 by Pyerre
There two types of 41's, and they are recognized by the LCD's window. Have a look at yours and check for their corners: are they clear, sharp 90º edges? If so, yours is a so called fullnut, an earlier design, and this type has a "secondary" board (in fact, the mainboard) inside it with all chips and electronics components built on it, except for the LCD's drivers, that are built in the LCD's assy.
If the LCD has an extra thin black frame (internal) with rounded edges, then you have a halfnut type. This type has newer design and uses SMT (Surface Mounting Technology) components. There is one PQPF (Plastic Quad Package - Flat) CPU built in the keyboard and the other chips are built in the LCD assembly (RAM, ROM and Display Driver - one could call it an R2D2, but this is the designation given to the Voyagers' CPU).
The halfnuts are harder to repair, but they tend to be more reliable (some users do not like their key-"feeling"), and I tell you that I have one HP41CX and one HP41CV halfnut (newer design) and one HP41CV fullnut (earlier design). The fullnut has some problems regarding bad contact between the mainboard and the keyboard, one of the most symptomatic parts of the calculator. If this contacts are bad, the calculator fails often. I have opened many, many fullnuts, but I opened just a few halfnuts. Maybe others have different experiences. My both halfnuts were opened no more than 8 times, counting both of them. In all cases, there was a problem of bad contact between the BAT/IO assembly and the mainboard. Just cleaning. But the fullnuts have three contact sets to be periodically checked, and two of them are under the mainboard.
I think that's all. If you believe you need to, there is no big deal opening the HP41 fullnut. Check the LCD's corners and let us know.
Luiz C. Vieira