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Hi folks - new to the forum so please go easy with a "newbie".

I have an HP41CV (Fullnut I think you call it) which has seen better days - badly corroded battery terminals, and intermittent contact between the logic board and keyboard. Rather than scrap it, I pulled it to pieces and hard-wired the logic board to the keyboard. Temporarily I've connected a 6v supply directly across the appropriate keyboard traces.

It doesn't work! Here are the symptoms:

At power-up the display shows the "flying duck" in the leftmost display position and the PGRM annunciator is on. None of the keys has any effect except:

* Pressing the ON key causes the display to briefly show "MEMORY LOST" and the beep to sound before going back to the original display.

* Pressing R/S changes the display to "0," at the left and "00" at the right. Pressing R/S again puts it back to the original display.

Before throwing it in the bin I wondered if those symptoms give any pointers to what the fault might be.

I've very carefully check my hard-wiring of the logic board to the keyboard - everything looks correct with no shorts.

Grateful for any help,
Steve

Anytime a 41 displays MEMORY LOST at power on (other than after a complete reset of memory) is usually a sign of a bad rom or ram.

Realistically, the only way to troubleshoot is with the HP 41 service rom.

Thanks Randy - looks like it's on its way to the bin!

Steve

Do NOT throw it!

If it has a good keyboard and LCD, it can probably be salvaged and converted to a 41CL by replacing the logic board.

At worst, it will most likely have some use for spare parts!

Yes - the "bin" in question is the spare parts bin ;) I have 3 other HP41s, so it might come in useful at some stage.

Next job is to replace the "crumbling" drive wheel on my card reader!

Thanks for the advice,
Steve

How can I do it? How "transform" my HP-41CV into a HP-41CL? regards...

Hi dinamarco,

Checkout this 41CL Link . You will find all the necessary information about the 41CL upgrade. Also checkout this for further information.41CL wiki link
Regards, Kerem