CX Revival

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CX Revival

Postby Duncan » Sun Jan 26, 2020 8:52 pm

Hi All
I am trying to gently coax a HP41CX back into life after not being used for many, many years. After powering it on (ports empty) the Catalogs work but the calculator seems to be full of random data (at one point making the calculator thinking it had > 700 registers of main memory (if only)! I was hoping a 'Memory Lost' would solve the problem but the back arrow button seems to work only randomly so I am having hard time to do 'Memory Lost'. So I took the batteries out and left it for over a week now and it still hasn't lost its memory!!!!! Has anyone got any ideas how to solve this for this wonderful amazing machine (e.g. short battery terminals?) or is the random data in the calculator due to some other problem?
Regards
Duncan
Duncan
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Re: CX Revival

Postby Duncan » Wed Jan 29, 2020 2:04 pm

OK folks
I have got the CX working!! but more by luck I think. Eventually it gave a memory lost after I did a SIZE command!? Everything seems to be working except the Back Arrow and R/S buttons also ports 1 & 4 seem to corrupt the machine when I plug anything into them but ports 2 & 3 work fine. Does anyone have any suggestions about getting the CLX and R/S keys working and what might be the reason for ports 1 & 4 causing problems? As far as I can see (without taking the calculator apart) the port connectors look in very good condition.
Duncan
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Re: CX Revival

Postby Garth » Wed Jan 29, 2020 8:04 pm

I don't know the answers to your problems, but I'm watching your progress with interest. In case you can't get it going, one of the links in the HP-41 section of my links page on my (mostly 6502) website is:

    Vintage Calculator Repair (Bruce Larrabee's repair service) Neck surgery and deaths in the family made him unable to maintain the calculator repair business for a while, but the Dec 13, 2019 update on his site says he's back to the repairs and has some improvements in his process that should speed things up. He has a new phone number, 541-731-5130, which you can call 9:00 am to 8:00 pm PST.  Note that he has moved.

I don't have any experience with that service myself, only an interest in helping others keep the 41's alive as many decades as possible. I still use my own 41cx from 1986 daily, and have not had any real trouble with it, and in fact I just added Diego's Clonix-D flash module to it 18 months ago with some of Angel Martin's new ROM module images which are super nice additions.
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Re: CX Revival

Postby Duncan » Sat Feb 01, 2020 12:28 pm

Hi Garth
Thank you very much for your information any is helpful and I will certainly investigate that resource. I love the HP-41 and HP-IL. I have 2 HP-41CX's!! from the 1980's. Sadly at the time I was involved with their use I developed cancer that caused an archiving of life, memory and and many other things. I have always kept my eye on HP things and HP-41/IL and going through stuff came across my old HP-41's (and other modules & bits and a box of thermal paper)!

I am now reviving my archived state and continuing where I left off all those years ago!! Especially with virtual 41 & IL I am using and I have just got a PIL box too!

I have got one HP-41 working although the CLX & R/S buttons and ports 1 & 3 aren't working and the second HP-41 seems completely dead but I am in the process of replacing the battery/port block on that one. I will post any news as I progress (or not).
Duncan
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Re: CX Revival

Postby Duncan » Sun Feb 16, 2020 8:37 pm

Hi All
Update - the CX threw a wobbler along with a memory lost and in the process losing another port (2), just port 3 left the 'wobbler' also stopped the 0 key working. The loss of the 0 key makes it very difficult to use. However I managed to restore it's configuration by recreating the configuration in my virtual 41, then writing the configuration to the virtual disk drive and then using my newly acquired fantastic PIL box and REAL HP-IL was able to read the configuration back into the real CX!!

Not having much luck with my other CX (sad). In this one the battery/ports connector was entirely ruined but even with a brand new part it seems completely dead which I find difficult to believe because it's has just been sitting in a box for 25 years. This is the newer one and I had high hopes of getting it going again. Does anyone know if the main PCB can be removed and if so how to do it? It seems pretty well fixed to the front (i.e. keyboard) case.
Duncan
Duncan
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Re: CX Revival

Postby Drulli » Sun Mar 29, 2020 12:09 pm

Hello Duncan,
difficult to say, what's wrong without any pics from the inside. Strange behavior of the hp41 can be caused when the contact between the keyboard board and the PC board is bad. Very often the posts which hold the PC board in place, are broken.
I would open the CX and check the contacts.

To open the CX remove the rubber feets and unscrew the back side from the front.
Details can be found in the Service Manual.
HP-41 CX, HP-41CV, Printer 82143A, Cassette Drive 82161A, PILbox, 82104A Card Reader, MAth I, Circuits I
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