Can my CV take a CL board?


I have a fullnut HP41CV, SN 2427*******. I know from past openings that the innards look exactly as they do in the CL manual--i.e., I know I have the coil-edged thing providing contact which relies on the integrity of the screw posts, and all the pics look exactly as I remember things. FixThatCalc has worked on this unit before, but I know for a fact this involved largely reinforcing cracked screw posts and cleaning things. I am positive that all electronics are original.

I remember reading somewhere how one can determine one's HP41 can accept the CL board based on serial number, but I can't find the article or link anywhere.

Any guidance would be well received. I vaguely recall this issue being discussed recently.



Hi Les, look please at this I think that your CL should be ready for the transformation, but read please the post, Geoff all explained, and read please what Randy said about serial numbers..........!

PS: if you are not sure of yoy CV, you can buy the HP41C for 999EUROS (see other post)! with all that money it MUST be absolutely the "best donor"°=)

Edited: 3 June 2012, 7:25 p.m.


Thank you!

That thread led me to the correct page in the Manual that I had somehow missed.

It seems that a fullnut CV later than SN 2003xxxxxx has the correct display driver and won't need the capacitor modification. Mine is four years newer. That's a relief because I don't want to go anywhere near this calculator with a soldering iron. I also know for a fact that I have the desired wire wrapped connector inside, so I should be ready to rock.

My main reservation stems from nostalgia. This CV was my first HP, and indeed getting it fixed a few years ago lead me to this forum and a little collecting. I have already thrown money at two FixThatCalc repairs, and would do it again, but I do fear wreaking irreparable havoc on my most beloved unit.

Thanks again,



You are welcome. On the beloved machines which I own from the beginning of their life I'm scared to put even the hand on.......
You talked about cracked posts.....just a few days ago my fullnut CX started to be sick and I was not yet able to fix ......its cracked keep a "MEMORY LOST" I must embrace "her" !


If you are comfortable with opening and closing your 41, and you don't want the serial connection, that's practically all that has to be done. Dropping in the replacement CPU board is a trivial exercise, modulo care to avoid static discharge. Refastening the screws is always fun, given that they have to be tightened firmly, but not so firmly as to crack the posts.

Using the antistatic bag that the CL board comes in to store your old "brains" would help ensure you could restore your machine to its original state if the need ever arose.


Howard, it seems a trivial exercise to most, but I have had run-ins with those posts before. Indeed, after a couple of bad experiences I have learned it is false economy for me to tinker in the guts of these gizmos. If Monte is comfortable doing it, I may ask him to send the board directly to Randy on my behalf. The postage, and likely duty, saved by sending within US instead to Canada would go at least half way toward what Randy would charge me to open the calc, pop in the board, reinforce the posts if necessary, reassemble and test, and send back--nice and clean and with fresh batteries like he always does. If Randy ever reopens his service queue, I will certainly ask him.

I have a PIL-Box and NoV-64 and have become increasingly proficient as I explore various means of getting stuff back and forth between the calculator and computer. As long as these peripherals work with a 41CL, I think I would survive nicely without the built-in serial connection.

I will write Monte and Randy in the days or weeks to come to see if they could coordinate this for me. Thankfully this is direct sale and not TAS, so I would hope that Monte would not have any reservations about sending an order to a trusted third-party address.


Edited: 3 June 2012, 8:33 p.m.

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