The Museum of HP Calculators
HP Forum Archive 01
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Message #1 Posted by Chris S. on 28 July 1999, 11:46 a.m.
I recently bought a 41CV at a car boot. Found a few problems with it mainly corroded battery terminals, after careful cleaning etc. I reassembled and got the memory lost message (which I think is normal) which then dissappeared. Problem is although all the keys appear to work properly, the appropriate digit appears when you press the key, the display goes blank as soon as I release the key! the information is still there as it re-appears at the next keystroke. Anyone got any ideas?
Message #2 Posted by dave on 28 July 1999, 6:28 p.m.,
in response to message #1 by Chris S.
Sounds like you have either a stripped or broken screw post holding the calc together, hence when you apply pressure to the keys the battery connection is doing its thing with the circuit board. And when you release the key the two halves are seperating just enough to lose the display. Try holding the top half of the calculator down firmly with one hand and use the other to enter a few keystrokes and see what happens.
Message #3 Posted by Chris S. on 29 July 1999, 4:06 a.m.,
in response to message #2 by dave
Thanks dave.........I did have that problem initially but after the refurb I'm convinced the connections are good. The display fires up on any key press whether firm or light and I've even managed to make it go through what appears to be a self test where the display scrolls round all of the available functions. I did this by accident a few times but can't seem to find the key stroke combination that activates it. The 'beep' function also works fine. The only thing I can think of is that maybe one of the tracks on the underside of the main keyboard has corroded or broken but it seems as though that was not meant to be removed.
The only other thing I could try is another mini (processor) PCB in case there is a problem with that.
Still open to suggestions.
Message #4 Posted by Marwan Joury on 29 July 1999, 12:17 p.m.,
in response to message #3 by Chris S.
The "Self Test" feature that you found is actually the catalog function. This function catalogs three things:
catalog 1: press shift (yellow) ENTER^ followed by "1" gives a listing of all programs in memory.
catalog 2: shift - ENTER^ - 2 lists all functions in ROM modules (whether written in user code or machine language.)
catalog 3: shift - ENTER^ - 3 lists all internal functions.
The CX has additional catalogs which include the alarm catalog (accessed via "almcat" on a C/CV -- also works on a CX, and the extended memory catalog ("emdir" on a C/CV.)
Good luck with your other problem.
By the way, you can stop any of the internal catalogs (1, 2, and 3) by pressing R/S and then single step through them by using SST (single step (forward)) and BST (single step (backward)).
Message #5 Posted by Chris S. on 29 July 1999, 12:26 p.m.,
in response to message #4 by Marwan Joury
Thanks Marwan......I'm learning all the time. Do you know where I could get a user manual for CV?
Message #6 Posted by Marwan Joury on 29 July 1999, 3:17 p.m.,
in response to message #5 by Chris S.
I just got the HP Museum CD-ROM set. This includes the users manual for the HP41C/CV in PDF format. It also has a whole lot of other interesting stuff. If you want a paper version you may want to try ebay (www.ebay.com). They often have HP41 stuff for auction. Try the following search string "(hp,hewlett) calc*" note that there are NO spaces between the parenthesis.
Message #7 Posted by Chris S. on 30 July 1999, 4:14 a.m.,
in response to message #6 by Marwan Joury
Marwan........Thanks for the info.
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