"Packing" syndrome of my HP-41CV



My HP-41CV displays "Packing" after each key press and doesn't calculate anymore. If I press "Prgm" then it endlessly displays "Packing" and "00 REG" alternatively ...

And it keeps doing it even after a reset (Left arrow+ON -> Memory Lost) ... :(

Any idea about what's happening ?



Is it a full nut or half nut ?

(check the display corners)


My HP-41CV seems to be "Halfnut" (Rounded corners in display)


So, simplified internally in terms of electronics ... which would hopefully lessen the chance of a hardware fault, but can't be ruled out.

I work with electronics repair all day , but have never took either full or half nut apart as yet - never had the need so far. (although I do have a halfnut right now which is about to be opened up and checked out for a DOA problem which I'm thinking is the end result of battery leak)

I take it the battery terminals are clean and no history of battery leakage ?

After excluding battery leakage problems It could be an actual memory problem, dodgy cap or similar or simply poor/iffy IC interconnections (poor soldering), if it can't access all the memory it's gonna think it's full of data hence the constant packing.

All just guesswork from me really, but if there's no obvious battery leak and a reset isn't curing it, then it obviously needs opening up to further discover where the problem lies.

Edited: 30 Oct 2013, 4:58 p.m.


Thanks for your answer ... so, that's what I feared ...

Anyone interested in this HP-41CV ? (for parts now :) , everything running fine before this problem, and with "Financial I" module inserted ...

Price = The shipping costs from Belgium ...


I don't 'need' another ....but I have emailed you :)


I could have a look at your unit and try to revive it. I am based in The Netherlands, so relatively nearby,

Regards, Meindert


Remove all modules, reset and retest.

If it does not behave correctly, it's a parts machine since the rom and ram are part of the display driver module and are not field replaceable. Short of corrosion on the board somewhere, there is little considered repairable on a half nut.


Thanks for all your answers. I don't think I'll try to have it fixed, since I bought it for 5 EUR ...


I had the same situation once, bought an old 41CV on ebay advertised as broken, and had it up and running with a few hours. Just contact me by email, and I will gladly help you to turn € 5 into a much higher value!



i experienced something similar today with my hp41cx. first it froze then it woke up again and packed endlessly. then it froze again and i was not able to bring it back to life.

i shortened the battery contacts for a few seconds but that did not help.

then i found a source on the internet that says that you have to shorten several minutes, up to 15!

i measured a voltage of 0.6 v on the contacts of the frozen calculator. i covered the contacts with aluminum foil and the voltage dropped slowly to 0.1 v within about 10 minutes. i reinserted the batteries and the calculator worked again.

i also learnt that the reason for freezing are an hp-il and a infrared printer module that were in the calculator at the same time.

hope this helps!


The 82160A HP-IL module and the 82242A Infrared Printer module can both be installed simultaneously if you set the switch on the HP-IL module to the printer-disabled position.


wow, two things learnt in a single day! that's high above average!

thanks a lot,


Possibly Related Threads…
Thread Author Replies Views Last Post
  HP 41CV Repairs William Mabotja 3 1,581 11-20-2013, 04:45 PM
Last Post: Mike Powell
  HP-41CV - A Walk Down Memory Lane Tom Lewis 9 2,693 03-18-2013, 11:14 PM
Last Post: BShoring
  HP-41CV power problem Don Davis 2 1,250 10-11-2012, 09:13 PM
Last Post: Don Davis
  HP-41CV layout vs Voyager's, 35s Ben Huntsman 17 4,485 09-17-2012, 05:30 PM
Last Post: Luiz C. Vieira (Brazil)
  HP-41CV System II aj04062 1 1,138 06-22-2012, 08:49 PM
Last Post: Allen
  HP-41CV "tall keys" version Ignacio Sánchez 16 4,379 06-11-2012, 04:59 AM
Last Post: Diego Díaz
  HP 41CV defective aurelio 7 2,448 05-16-2012, 03:54 AM
Last Post: Frank Boehm (Germany)
  HP-41CV dilemma Matt Agajanian 41 10,431 03-13-2012, 10:56 PM
Last Post: Luiz C. Vieira (Brazil)
  Defective HP-41CV for 41CL? Ernst Fueloep 3 1,325 12-13-2011, 12:57 AM
Last Post: Juergen Keller
  HP-41CV "HFF" ROM set Eric Smith 4 1,631 07-26-2011, 02:13 PM
Last Post: Eric Smith

Forum Jump: