HP-41C - Memory lost

[Vintage63]

Hello everybody!!
My calculator throws a 'memory lost' every time I move it without being careful.
Today I picked it up and in doing so banged it against my monitor, memory lost.
Miscalculated the distance between the two.
If I put it down with a slight 'bang' it doesn't switch on again unless I deliberately bang it on the desk and remove the batteries multiple times.

This is really annoying. I've had enough of reprogramming it every time.

How could I solve this problem once and for all? I don't want to be experimenting every trick in the book.

Thank you
Marco

[Steve Simpkin]

There is a good chance that some of the support posts have cracked and are no longer keeping the top and bottom halves of the case tightly together. This causes a poor connection with the circuit boards and the flexible interconnect. Could also be corrosion on the battery contacts. I would look at that first but be careful cleaning them as they are delicate.

https://www.hpmuseum.org/cgi-sys/cgiwrap...cgi?read=2

[aurelio]

Marco, check also, please, into the battery pack the springs if contacts are clean.
And, please, don't bang it too much
Cheers
Aurelio

[Vintage63]

Hey, I'm no Hulk!! :-)
I pick it up, use it and relocate it where it normally sits. It may happen that sometimes I'm not using a feather touch and I lower it on the desk without the 'air cushion'. :-)

[Vintage63]

I cleaned the battery pack contacts with a Dremel copper brush and cleaned the battery contacts with an earbud dipped in white spirit. I tried to tighten the screw a bit more but none of them budged so they should be ok, I guess.

[aurelio]

(02-01-2023 09:23 AM)Vintage63 Wrote:  I cleaned the battery pack contacts with a Dremel copper brush and cleaned the battery contacts with an earbud dipped in white spirit. I tried to tighten the screw a bit more but none of them budged so they should be ok, I guess.

Hi Marco!
Usually with broken posts issues, pressing the case, expecially in the upperside (it means near to the battery holder) you can notice the display changing. You can try to open the calculator, removing the four screws and checking with the help of a magnifier lens, the healt of your posts. At this point you can also check the quality of the contact between the CPU and the keyboard and the healt of the zebra connector. Of course opening the calculator is a risk...but also tightening several times the screws.

[AndiGer]

My guess - especially if it‘s a made in USA 41C and therefore holding the CPU by nuts - some corrosion under the I/O port or weakness of the „foam“ under the I/O port

[rprosperi]

(02-01-2023 07:26 PM)AndiGer Wrote:  My guess - especially if it‘s a made in USA 41C and therefore holding the CPU by nuts - some corrosion under the I/O port or weakness of the „foam“ under the I/O port

Only the very early 41C units used nuts to retain the boards. I believe they switched to other methods before the end of 1979. Pretty sure Geoff Quickfall posted here some years ago with exact details.

[Vintage63]

Hello again and thank you for your inputs.
My 41C has S/N 2052A00467 so it was built in the USA, A, in 1980 the last week, 52, of that year.

I'm not too keen to open it with the risk of braking what still look sound. I believe it is a 'full nut' as the cornner of the display are at right angles.

I have just pressed the case of the 41C on the top left corner of the dsiplay and the LCD behaves like every LCD when pressed, broken posts?
Other ideas?

[AndiGer]

If it‘s a tall key version made in USA
https://www.hpmuseum.org/cgi-sys/cgiwrap...ead=225203
I think it has the nuts. All A 41C I‘ve seen with tall keys had the nuts IIRC.
As long as you know how to get it back to work and mind open it for inspection you can simply leave it as it is

[Vintage63]

an ancient philospher said 'I know that I don't know' (more or less)
I'm in this situation, I know nothing :-)
Probably the keys are tall, I'll have to check. This calculator has been bugging me for a few years, so either I leave as is or I throw it away.
The card reader is a mess and although I changed the traction wheel it doesn't want to read my cards, it pulls them through though.
Is there really, really, anybody on this planet that can really fix it and not put only band aids on it to keep it working? I wonder.
DIY is fine, but I know my limits.
I know where to go when I don't know what to do on vintage fountain pen but this is really bugging me :-(

[AndiGer]

Before you put it into the basket without any repair attempt you can open it and don’t loose anything - only a chance to win! Never give up!
I have a card reader that worked before after some repair. Nowadays it doesn‘t. I put it aside and try to get it back to live when the limits to be frustrated are high enough. And repeat when it doesn‘t work this time. Happened several times now. But I‘m optimistic it will work again. I hope due to this site and its members.

[Vintage63]

After checking the link posted by AndyGer I can confirm that mine is a 'tall key' 41C