Problem with 41C

[heliocrono]

I recently purchased a 41C (No Modules) calculator. It turns on and I can enter numbers with the keys. But when I press ENTER the calculator turns off. After a few minutes it appears on. The blackout occurs the same if I do sin, cos, tan or even LOG, gold key, etc. operations. It seems to turn off only with the top keys. It seems like it can't perform stack operations. The ALPHA, PRGM and USER keys work.

The calculator is perfect, very well maintained with no corrosion. The batteries are new, and the module bay is immaculate. What can I do?

I have done a MASTER RESET (<- and ON), and MEMORY LOST appears, but then the error persists. I have followed the steps in the book "Extend Your HP41" by W Mier-Jedrzejowicz (section 4.1). I am asking for ideas, or alternatives.

[rprosperi]

Try holding the calculator down pressing firmly/gently on the two outer rails, between the top two rows of keys, and then press the buttons for your testing while maintaining the pressure. If it works while pressing like this, it means one (or both) of the upper posts, or the back of the case (under the feet, where the screws pass thru the sockets) is broken. There are repair options for these problems but step 1 is finding out the cause for sure.

Also, try using other batteries. Even though you think the ones you have are new, one or more cells might be bad or low, leading to shutdown from overall low voltage. Brand new N cells should be about 1.6V or even a bit higher.

[Geoff Quickfall]

Dr. Prosperi has nailed it.

[rprosperi]

(10-24-2024 12:50 AM)Geoff Quickfall Wrote:  Dr. Prosperi has nailed it.

Just guessing really. Though these are common causes, there are so many things in a 41 that could lead to his symptoms, I thought I'd just get these simple ones out of the way to allow real experts, like you, offer better advice, but maybe I'd get lucky and hit it.

[aurelio]

(10-24-2024 12:50 AM)Geoff Quickfall Wrote:  Dr. Prosperi has nailed it.

I agree with doc. Prosperi, that is the first check to perform, prof. Quickfall

[aurelio]

If really it is a broken posts' matter, here is an interesting article to read

[heliocrono]

(10-23-2024 10:25 PM)rprosperi Wrote:  Try holding the calculator down pressing firmly/gently on the two outer rails, between the top two rows of keys, and then press the buttons for your testing while maintaining the pressure. If it works while pressing like this, it means one (or both) of the upper posts, or the back of the case (under the feet, where the screws pass thru the sockets) is broken. There are repair options for these problems but step 1 is finding out the cause for sure.

Also, try using other batteries. Even though you think the ones you have are new, one or more cells might be bad or low, leading to shutdown from overall low voltage. Brand new N cells should be about 1.6V or even a bit higher.

I have tried pressing on the two outer rails, in the position mentioned. But nothing happens. I press firmly, making sure not to break the casing, but the screen remains blank. The photos sent by Aurelio give me an idea of ​​the positions.

I have also performed the reverse operation, once there are digits on the screen, I press to see if they disappear, and nothing happens either. I just have to press a key on the top to turn it off again.

As a note, on many occasions, when the calculator is turned on, the word NONEXISTENT appears.

[heliocrono]

(10-23-2024 10:25 PM)rprosperi Wrote:  Try holding the calculator down pressing firmly/gently on the two outer rails, between the top two rows of keys, and then press the buttons for your testing while maintaining the pressure. If it works while pressing like this, it means one (or both) of the upper posts, or the back of the case (under the feet, where the screws pass thru the sockets) is broken. There are repair options for these problems but step 1 is finding out the cause for sure.

Also, try using other batteries. Even though you think the ones you have are new, one or more cells might be bad or low, leading to shutdown from overall low voltage. Brand new N cells should be about 1.6V or even a bit higher.

Regarding the proposed solution for the batteries, I put in a set of new batteries taken out of the package, and then some already used ones. The end result is the same.

[aurelio]

(10-23-2024 12:48 PM)heliocrono Wrote:  I recently purchased a 41C (No Modules) calculator. It turns on and I can enter numbers with the keys. But when I press ENTER the calculator turns off. After a few minutes it appears on. The blackout occurs the same if I do sin, cos, tan or even LOG, gold key, etc. operations. It seems to turn off only with the top keys. It seems like it can't perform stack operations. The ALPHA, PRGM and USER keys work.

The calculator is perfect, very well maintained with no corrosion. The batteries are new, and the module bay is immaculate. What can I do?

I have done a MASTER RESET (<- and ON), and MEMORY LOST appears, but then the error persists. I have followed the steps in the book "Extend Your HP41" by W Mier-Jedrzejowicz (section 4.1). I am asking for ideas, or alternatives.

Hi there, did you try the test which Robert Prosperi suggest you, I mean "pressing firmly/gently on the two outer rails, between the top two rows of keys, to press the buttons for your testing while maintaining the pressure"?

[heliocrono]

(10-24-2024 05:28 PM)aurelio Wrote:  

(10-23-2024 12:48 PM)heliocrono Wrote:  I recently purchased a 41C (No Modules) calculator. It turns on and I can enter numbers with the keys. But when I press ENTER the calculator turns off. After a few minutes it appears on. The blackout occurs the same if I do sin, cos, tan or even LOG, gold key, etc. operations. It seems to turn off only with the top keys. It seems like it can't perform stack operations. The ALPHA, PRGM and USER keys work.

The calculator is perfect, very well maintained with no corrosion. The batteries are new, and the module bay is immaculate. What can I do?

I have done a MASTER RESET (<- and ON), and MEMORY LOST appears, but then the error persists. I have followed the steps in the book "Extend Your HP41" by W Mier-Jedrzejowicz (section 4.1). I am asking for ideas, or alternatives.

Hi there, did you try the test which Robert Prosperi suggest you, I mean "pressing firmly/gently on the two outer rails, between the top two rows of keys, to press the buttons for your testing while maintaining the pressure"?

Yes, indeed. I did the test as I understood it, without opening it, pressing in the space between the upper keys, pressing firmly. And the calculator behaved the same. I understand that the test is to check the tenacity of the posts. But I must say with regret that nothing happened. It's a shame, because this is my first 41

[aurelio]

(10-25-2024 05:36 AM)heliocrono Wrote:  

(10-24-2024 05:28 PM)aurelio Wrote:  Hi there, did you try the test which Robert Prosperi suggest you, I mean "pressing firmly/gently on the two outer rails, between the top two rows of keys, to press the buttons for your testing while maintaining the pressure"?

Yes, indeed. I did the test as I understood it, without opening it, pressing in the space between the upper keys, pressing firmly. And the calculator behaved the same. I understand that the test is to check the tenacity of the posts. But I must say with regret that nothing happened. It's a shame, because this is my first 41

Hello, if you have also checked with new fresh cells and the problem persists, then you can try this procedure, before to open the calculator and check inside.

You just need to remove the 4 rubber feet in the rear of the calculator. This way you can access to the four screws that Bob was talking about. You can gently try the Tightness of these screws, if any of them is loose, but do not insist too much. You can check this way also if the posts are broken/cracked. when the screws do not properly close the case of the calculator there is bad contact between the PCB and the keyboard (zebra connector)