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HP Forum Archive 10

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HP41CX scary moments (or: There is a Poltergeist with my calculators)
Message #1 Posted by Vieira, Luiz C. (Brazil) on 15 Jan 2003, 4:29 p.m.

Hi, folks.

A few days ago I posted a message about an HP25 with a strange behavior. Now it's the time to try to figure out what happened with my HP41CX's time module.

I took it yesterday night and turned it on. [MEMORY LOST], no matter. But no switching to OFF; instead, an annoying, persisting [MEMORY LOST]. Last time I saw it, my HP41C was sent to repair at HP Service Center and returned with a new 1LA701 (RAM chip with first 16 registers, the ones used by the system to store the stack registers, ALPHA characters and those well-known synth regs: "a", "b", "d", "Q",...). And the HP41CX was with the same symptom. If this is the cause, I can test a spare 1LE701 I have in a broken HP41C motherboard, but my 41CX is a halfnut... I cannot se a way to transplant organs from a fullnut to a halfnut.

The [MEMORY LOST] also had a brief flashing, about 1 sec. span, and the BAT annunciator lit after a few seconds. I remember I read about time module crashes and that it needed to be removed for a few minutes and then reinserted. In an HP41CX? How could I do that???

Well, remove batteries and wait for a while. I decided to change the batteries in the pack for new ones and tested the removed pack in an HP41CV, halfnut too, and the BAT annunciator stood still: did not lit on. Batteries O.K.

LBL 01 I inserted the batteries back in the HP41CX and the [MEMORY LOST] remained, but this time the [<-] cleared it. Wow! Let's put my heart back in my chest. And for a last test: [SHIFT] [ON] and... blank display! No watch display, no turn ON, no nothing. Remove batteries, remove the heart from the chest and keep in hands again, wait for a while (I stop smoking about 8 years ago, and I'm lucky not smoking today...). RTN XEQ 01; this time, instead of [SHIFT] [ON] I tried [CLOCK] and... There you are, my dear; where have you been for the last hour?

Well, what to conclude? For me, a possible bad contact BUT complete isolation from the battery connector caused the time module to behave erratically. The system interruption caused by [SHIFT][ON] was not successful to bring it back from this condition, but [CLOCK], as a function, takes a different route. Maybe if I left the calculator for a couple of hours without the batteries it would get back O.K., but I was in a hurry to know what was going on. I hope this experience is useful to someone else.


Re: HP41CX scary moments (or: There is a Poltergeist with my calculators)
Message #2 Posted by Ernie Malaga on 15 Jan 2003, 5:18 p.m.,
in response to message #1 by Vieira, Luiz C. (Brazil)


If you decide to get your HP-41CX exorcised, we'll all pray for it.

Last time something unexplainable happened to me, it was on a borrowed HP-65. I had one devil of a time explaining to its owner that I hadn't broken it!


Re: HP41CX scary moments (or: There is a Poltergeist with my calculators)
Message #3 Posted by Vieira, Luiz C. (Brazil) on 15 Jan 2003, 5:29 p.m.,
in response to message #2 by Ernie Malaga


Literaly, God bless you, Ernie. And all of you who want too...

I'm not a skepticle guy, I do not play with religious stuff, but there are moments we can sit back and laugh about some strange facts. Mostly when they are in the past...

Once a friend asked me to use my HP41C. He took four weeks to give it back to me. I was completely pissed off, and he was a little shy. I forgot the byte-jumper assigned to the [Sigma-} key and the calculator was in USER mode. Not necessary to say the calculator almost freaked him out.

Sometimes things happen.

Cheers. And thanks.

Re: HP41CX scary moments (or: There is a Poltergeist with my calculators)
Message #4 Posted by David Smith on 15 Jan 2003, 5:54 p.m.,
in response to message #1 by Vieira, Luiz C. (Brazil)

On the halfnut machines, if you are testing them with a battery pack clipped across the main capacitor then you will see the BAT indicator on. Apparently you have to bring power in through the legitimate route to get the machine to properly monitor the battery voltage.

I have seem machines with good batteries indicate BAT because of (often invisible) contamination between the contact assembly and the keyboard. They function normally except BAT comes on (and often times the card reader will not work properly).

Re: HP41CX scary moments (or: There is a Poltergeist with my calculators)
Message #5 Posted by Michael Meyer on 15 Jan 2003, 11:37 p.m.,
in response to message #4 by David Smith


I've often said that using my HP's is a, "religious experience." (I mean, have you ever just sat and LOOKED at an HP-19C? or an HP-67? or 97... or 25....)

You've given this a new meaning.... I will pray that your "higher power" wins the day!


Re: HP41CX scary moments (or: There is a Poltergeist with my calculators)
Message #6 Posted by Vieira, Luiz C. (Brazil) on 16 Jan 2003, 12:20 a.m.,
in response to message #5 by Michael Meyer

Hi, Doc;

thank you for "comming" so fast...

Hey, a few months ago, one of the contributors passed an interesting "prescription" to another, desperate contributor: "Take two HP33 and call me in the morning". If the "medicine" was other than the HP33, I am sure they were "equivalent". That made me remember you.

We must not forget the good moments, too. The ones I'm celebrating everytime I look at them are related to an HP55 and an HP41C.

This particular HP41C was my first Hewlett-Packard calculator, and it had, till last December, two RAM IC's soldered "upside down", meaning they were rotated 180 degrees by this insane writer. Yes, I did this in the mid 80's, I'm not sure about the year (in one previous post I wrote the year, but I am not quite sure about it). After seeing another HP41 with the same mainboard, I tried to kill myself but decided that I should first undo that stupidity. It worked perfectly and I kept my soul untouched. The HP55 was given to me by a friend and it was dirty, with bad contacts and had a dead battery. After a first "surface cleannign" I reassembled it and the display was erratic. I thought it was lost, but once again I messed the stuff up: the contact lids were upside-down, too. Stupidity undone and my only one Classic is running as hell. And the battery was "revived" after a few sparky capacitve restauration.

Interesting calculator: the only one I have were I can place two numbers in the stack (X and Y), perform any of the two available conditional tests with keystroke sequences (x<=y nn and x=y nn) and verify that they are executed! I think a few other classics have the same conditional tests' functionality. When I first read the HP55 User's Manual and I saw it mentions that the only operations that perform different tasks in RUN and PRGM mode are [GTO] and [R/S] I thought: "What about the conditional tests?". I was surprised when I verified that the conditional tests in the HP55 perform the same task either in direct keystroke or in a running program.

I was used to see the HP41's YES and NO, or the complete disregard of any Voyagers with the conditional tests performed in RUN mode as direct keystrokes, that I felt amazed with this particular 55's feature. Too bad the only merged codes in its program structure are [GTO]nn, [x<=y]nn and [x=y]nn.

Wow, too much words. Sorry, guys.

Thank you for your "spiritual" support.

Best regards, Doc.

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