My 41CV won't turn on



#16

I was playing with the IR module. Everything was going well but then the calc turn itself off and I can't turn it on again. Check the battery it's kinda low. Replace new battery but it still won't turn on. Sometimes when I put in the battery pack it displays garbage and doesn't respond to keyboard. Take the battery out for a while now and reinstall it won't turn on again. What should I do?


#17

I have a buggy IR module (see earlier thread). I did notice some peculiar behaviour at one point and I needed to take all of my modules out and reset the calculator. This is done by holding down the ON and <- simultaneously, then releasing the ON key and finally the <- key. If the reset went well you will see MEMORY LOST. Fortunately, anything of importance on my CX I had in either cards or barcode so clearing the RAM was no loss. Looks like your RAM is corrupted if the display shows gibberish.

Since the reset, I have had no problems. The IR module still tests as BAD to TESTP, but it is partially usable and doesn't seem to interfere with the calculator operations. When you get your calculator going, run TESTP to see if the module is OK or BAD. Also, I have noticed that my IR module seems to slow down keypad response slightly though perceptibly. Indeed, when I had the difficulties warranting the reset, I took the module out very quickly after turning the calc off. I wonder now if the calc really was off, so now when I turn it off to remove or insert a module or peripheral I wait a couple of seconds just to be sure.

If the ON-<- reset combo doesn't work, there are other things to try--leaving the batteries out overnight, inserting them backwards to clear the constant memory are a couple of options I have heard of but I have never tried them myself.

An HP41 that won't turn on with good batteries installed is one of the most frustrating and dreaded experiences of those who love these calculators. If your machine can be revived without a service call to FixThatCalc.com or plamoid or someone of that ilk, I am sure someone here can help you.

Les

#18

CT;
The answer to your question may be in section 4.1 of "Extend your HP-41" by W. Mier Jedrzejowicz. I believe that section has been transcribed somewhere into this forum. It's too long for me to type out, and really too long since some dickwit keeps removing my posts. If you think you might have jiggled the rom just before the problem started then write to me and i'll tell you what i know to do about it by email. That doesn't dissapear.

BTW: i haven't gotten to the post office yet but your discs are all boxed and ready to go. I'm just working too much and too lazy when i'm not working to stand in a line.


#19

Hi, "db" --

Quote:
..., and really too long since some dickwit keeps removing my posts.

Don't you use password protection with MoHPC registration? If so, perhaps your posts aren't getting through, or only the Curator could possibly be the "d***wit". (Just kidding...) ;-)

-- KS


#20

Karl; I dunno. Maybe i forgot to hit the password. My computer usually does it for me, but not always. I know two of the posts did post, then turned to vapor overnight. No loss, just a coment about something interesting that Tony told someone, an offer of a partial calc to someone with a broke one, and something so forgettable that even i forgot it.

So tell me; should i be using a password or not? Personally, i'm proud of my spelling errors and would like to have them bronzed here at the forum, so i don't usually go back and edit.

#21

Chan --

I had some bizarre problems with my 41CX when experimenting with the HP-IL module while the IR printer module was installed. There was pgrogramming in the memory, including a bit of synthetic programming.

You should try the reset function: ON/backspace (<-) held down simultaneously. There may be another one that is more extensive.

I was able to cure my locked-up 41CX using the Extended function "PCLPS". You'll need an X-Function module to do the same.

http://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/archv016.cgi?read=90348#90348

-- KS


#22

I removed the batteries from the calculator since last night. I would put them back in and try again tonight. May be it would work but I sure don't know what else to do. As of last night it simply won't turn on and nothing on the display. The ON + <- routine didn't work.
The IR module is fine as I tried it on another 41. It could come loose while I was using it and cause the problem.


#23

Quote:
I removed the batteries from the calculator since last night. I would put them back in and try again tonight.

That's the recommended approach when a 41C locks up. It seems that with the CMOS circuitry in the machine, capacitance can persist and keep bad memory contents alive for quite a while. Leaving the batteries out for 24 hours can overcome this. I've had to do that with locked up 41s in the past.

Another trick is to reverse polarity on the batteries and briefly plug them in. I've used that successfully several times over the years.

Regards,
Howard


#24

I have seen HP41C's hold up for over a month without batteries (a week seems standard). Best way to really reset it is to open it up and short across the big filter caps a few times. While open, clean the usual suspects with alcohol.


#25

David; About 16 years ago i called hp somewhere in Oregon about a 41 that was talking in conji if i could get it to turn on at all. The tech said i could do exactly what you said, but he said that i should then leave it unpowered for three days till i put in the batteries. He then said if that didn't work i should short it out again and let it sit for 6 months. Buying my second 41 fit somewhere in there. The cause of all this fun was my picking up the 41, thereby wiggling the il module in it's socket while it was running the vertical curve program and printing.


#26

I took it apart shorting the capacitor and now when I push the on key it just emit a faint beep and nothing on the display. I can't turn the beep off until I remove the battery. Well I will leave it without the battery for a month or so and check back later.


#27

Did you clean the contacts and tighten the screws? Try squeezing (gently) the case halves together while turning it on. I had this faint beep when the calc had contact problems (either the zebra connector, or broken battery contacts).

Good luck

#28

 Howard Owen wrote:
> > I removed the batteries from the calculator since last night.
> > I would put them back in and try again tonight.
>
> That's the recommended approach when a 41C locks up. [...]

actually the HP-41CX manual recommends shorting the battery
terminals

> Another trick is to reverse polarity on the batteries and briefly
> plug them in. I've used that successfully several times over the
> years.

I have looked at the schematics of the HP-41 board and in both cases there are diodes that should prevent the discharge.

But if it works it works :-)

**vp


#29

Wow! After a couple days with the battery out I put the battery back in and press on. Voila! the "Memory Lost" is in the viewfinder. I am happy now....


#30

Well, It works for a while and then got back to what it was before. It may be a gonner.


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