|Re: Need help, why my HP-41CV do not work?|
Message #2 Posted by Vieira, Luiz C. (Brazil) on 18 May 2002, 4:04 p.m.,
in response to message #1 by Amedeo Muscelli
Hello; (where are you?)
Please, I did not spell check this post; forgive my mistakes... >-(
There are many reasons for this behaviour, but as you saw "MEMORY LOST", let's take it as a good reaction. The beep worries me a bit, but... <8-|
The best shoot would be DUST. Can you open the calculators?
After opening them, you should check for dust (mostly from leaking batteries, but as you mentioned they were stored, I guess the batteries were not in place. Is it correct? :-)). There is an assembly that contains batteries contacts and I/O access; this is the first one to be checked. Remove it and have a look in the contactcs made with the keyboard's PCB. If needed, use some non-agressive cleaner (alchool is an acceptable choice at first) and remove, carefully, as much dust as you can. Avoid excessive material, so it will not leak into the keys' contacts.
There are two basic types of 41's: one that contains a separate PCB with all electronics (some integrated circuits) except display drivers: they are named FullNut (or coconut) and, in this case, the PCB should be CAREFULLY removed and the contacts inspected and, if needed, cleaned. The other type is named Halfnut and does not have this secondary PCB. The single PQPF IC in the middle of the keyboard is the processor, as memory chips are built in the display assy (Wow! I learnt a lot reading the messages at this forum...). The halfnuts will not have other places to be cleanned.
BE CARE WHEN OPENNING THE CALCULATORS FOR THE FIRST TIME! The halfnuts have their beepers built in the botton half of the calculator's box, and the wires connecting it to the circuit are somewhat thin. Avoid tracting them! :-(
Job done, reassemble the babes and tell us the good news! 8-D
(If you have no good response at the first time, it is good practice to shorten the terminas of the two large electolytic capacitors, ALWAYS begining with the big one and then the smallest; this way, all previously trash stored in memory will be history, and your calculator will not be locked because of a software condition)