|Re: How to identify an HP-41C or CV?|
Message #5 Posted by Vieira, L. C. (Brazil) on 31 Jan 2007, 5:53 a.m.,
in response to message #1 by Tom Salmon
can you identify if yours is a halfnut or a fullnut? Please, see the picture below.
I have a halfnut HP41CV that behaves like an HP41C. The problem is that the halfnut models are not fully component serviceable, meaning they have too few components: the main processor and a hybrid IC, with memory (RAM/ROM) and display control. The halfnut HP41CX has an extra, small PCB, with the clock chip. The hybrid IC found in all halfnut HP41's is somehow equivalent to the Voyagers' R2D2, the RAM/ROM & Display Driver chip.
In my genuine halfnut 41CV, the upper RAM chips have gone bad, and the calculator allows maximun SIZE 063. In fact, the still working RAM chip is not good too, because either program or register contents mysteriously change, and the calculator freezes from time to time. In the fullnut models, chances are that replacing the RAM IC's will fix it. In the case it is a fulnut 41C, inserting the four extra RAM chips will give you a fully functional 41CV.
These RAM chips are not for sale (have never been), so you'd need a 'donator'. www.fixthatcalc.com may be a starting point.
Best regards and success.