41CX locks up when eXEQuting any program

[Alex Souza]

Hi everybody!

I am learning how to program the HP 41cx and for my disapointment it stops when executing any program even the simplest one.It shows that little arrow that apears when running a program and the machine doesn't respond to any key.The only way to get it working again is by pressing "on" and "cl x/a" at the same time.Talking about it to a friend we agreeded to open it and change the 2 capacitors it has.This didn't work.This issue started to happen sometimes but now I can't eXEQute any program.If somebody could help me I would be very grateful.Thanks.

[Ángel Martin]

(12-19-2015 09:11 PM)Alex Souza Wrote:  Hi everybody!
If somebody could help me I would be very grateful.Thanks.

Is this the only instance that shows the issue? Does it all work fine in normal operation, say for instance assign a function to a key and execute it, or running the CATalog 3? Can you SST the program?

[Alex Souza]

Hi Ángel! Thanks in advance for your attention! Yes,i think so,i can assign any function to a key,execute the cat 3 and sst any program.I assigned "fact" to the "LN" key and executed the factorial of 69 that is the highest value the machine can calculate and the answer seems correct - 1,7112 E98.Until a couple of days ago i could run a program without any problem but from time to time the machine started to show that problem.Once it could run a program but it seemed it wouldn't have enough energy to get to its end,it stopped in the middle but could get to the end of the execution of the program.Now the machine refuses to execute any program but all other function are all right.

[wojtek]

(12-19-2015 09:11 PM)Alex Souza Wrote:  Hi everybody!

I am learning how to program the HP 41cx and for my disapointment it stops when executing any program even the simplest one.It shows that little arrow that apears when running a program and the machine doesn't respond to any key.The only way to get it working again is by pressing "on" and "cl x/a" at the same time.Talking about it to a friend we agreeded to open it and change the 2 capacitors it has.This didn't work.This issue started to happen sometimes but now I can't eXEQute any program.If somebody could help me I would be very grateful.Thanks.

41c (I have no 41cx) has not any kind of reset nor factore reset. Remove the batteries for the time required to make it lose all memory and settings (my 41c, can keep data with batteries off for more than 10 days).

[Hans Brueggemann]

(12-19-2015 09:11 PM)Alex Souza Wrote:  Hi everybody!

I am learning how to program the HP 41cx and for my disapointment it stops when executing any program even the simplest one.It shows that little arrow that apears when running a program and the machine doesn't respond to any key.The only way to get it working again is by pressing "on" and "cl x/a" at the same time.

you may want to try a [GTO] [.] [.] and then [XEQ] [ALPHA] NAME [ALPHA]

hans

[TASP]

I wonder if it can XEQ a program in CAT 2, like from a plug in ROM ??

[Alex Souza]

Hi Wojtec,

After having changed the 2 capacitors the memory were lost - I could read "memory lost" on its display

[Alex Souza]

Hi Hans,

That didn't work - the display shows "nonexistent"

[Alex Souza]

Hi Tasp,

It can XEQ "clock" and "date" that are in CAT 2

[TASP]

Those are functions, look for a ROM with some programs in it like GAMES, STANDARD, AVIATION, HYDRACOMP, REAL ESTATE, etc.

[wojtek]

(12-20-2015 05:29 PM)Alex Souza Wrote:  Hi Wojtec,

After having changed the 2 capacitors the memory were lost - I could read "memory lost" on its display

In that case I would diassemble the unit and clean all the contacts inside with isoprophyl alcohol. In 41c there is a small board tied to the main board with 2 screws and communicating with the main one via contact joint. When the screws are fasten not strong enough or the contactcs are not clean the whole unit can behave abnormally

[Alex Souza]

Hi Tasp,

If I find a ROM for a good price I will try otherwise what would I do with a ROM without the 41

[Alex Souza]

Hi Wojtec,

I will open the machine and check it with a help of a friend who knows better than myself how to deal with electronics

[Alex Souza]

Hi everybody

The 41cx is working since yesterday but I don't know if it will tomorrow.I won't disassemble it as long as it continues to work

[quantalume]

(12-22-2015 12:01 PM)Alex Souza Wrote:  Hi everybody

The 41cx is working since yesterday but I don't know if it will tomorrow.I won't disassemble it as long as it continues to work

Usually, when this sort of thing happens, it's due to intermittent contacts between the batteries and spring terminals, between the batteries and flex strip, between the flex strip and main PCB, or, in the case of a fullnut, between the CPU and main boards. You need to make sure that all contact areas are clean, the screws are reasonably tight, the screw posts aren't broken, and the plastic or foam "springs" between the PCB connection points aren't "collapsed." Also, I've seen battery springs that look fine but actually have a surface layer of oxidation that prevents them making proper electrical contact.

[Alex Souza]

Hi quantalume,

Some days ago I pulled the spring terminals that make contact to the batteries and after reading what you posted I believe that this pulling of the terminals fixed the problem.Thank you all for the attention!

[Alex Souza]

Hi everybody,

The 41cx stopped working again so I believe that there´s bad (intermittent)contacts in other parts of the machine as pointed out by quantalume.I will open it and try to clean those areas.The believing that pulling the spring terminals had solved the issue was just a coincidence.