Vintage programmable calculators

Thread Starter

Leviset

Joined Jul 9, 2017
6
I'm new to this site so be gentle with me please! I'm a 68 year old retired IT Manager with a passion for repairing and programming vintage HP & TI Calculators. I have in full working order an HP-41CX complete with numerous modules, printer and card reader which needs some TLC. I also have a couple of TI-59s, one permanently locked to a printer (key is lost) which work but both card readers need repair. I'm also a member of the Hewlett Packard Calculator Club (HPCC).
I'm currently trying to get an HP-97 to work which shows no sign of wanting to power up.
My degree is in Pure Mathematics and I've reached a point where I'm being hampered by lack of knowledge in both Electrical and Electronic fields. I've been searching the Net for free online Electronic courses, which is how I found this site. Can other members advise me of the best books/courses, either free or reasonably priced, to start an introduction into Electronics (assume all I have in that area is A Level Physics from 1966).
An example of what is frustrating me - the HP-97 Desktop Calculator (RPN) was the first machine I wrote business programs on in 1979. I've picked up an used one from EBay complete with case, power adaptor and 2 battery packs.
The power adaptor works (my friend tested it with a multi-meter) and gives out 8v AC ≈ and the battery packs should be 4.5v DC output. Of The 2 packs that came with the calculator, one is useless and the other although brand new in a box will not hold charge - it's 35 years old but new in box. I've got a brand new battery pack from the USA which should be with me in 2 weeks.
Reading the Service Manual it appears that you have to have a good battery pack as well as the power adaptor input, but once battery pack is fully charged you can then run 3-7 hours on battery pack alone.
What I want to learn and understand is the circuitry involved, what it does, why it does it and how to be able to trouble-shoot and fix a power problem like this. How to track from the adaptor power in terminals and battery terminals as to how far in the chain power is getting to the point where it fails. To find any components that are not working and to be able to replace them, basically electrical and electronic diagnosis. Any help and guidance would be appreciated.
 

Thread Starter

Leviset

Joined Jul 9, 2017
6
A bright yellow Mult-meter missing a probe. A vintage multi-meter that works. Numerous tools (pliers, wire strippers, work bench, soldering iron (need advice on that as I think it's too big and I always end up chasing little balls of solder everywhere). We have a big Maplin Store here in Sheffield and I have enough money to buy other stuff.
 

AnalogKid

Joined Aug 1, 2013
10,055
Side comment: I dealt with HP and Tek power supplies for about 40 years, off and on, and I still can't say which design group is the more wacked.

ak
 

MrChips

Joined Oct 2, 2009
26,099
Ahh! A Level Physics with Michael Nelkon. Those were the good ol' days.

Why don't you collect something like slide rules? They never run out of power.

Want to see my collection of slide rules?
 

wayneh

Joined Sep 9, 2010
17,168
You haven't seen mine yet!

Edit: Wait a minute. The size of the collection or the size of the slide rule?
I was hoping the ambiguity would come through! But I don’t have a collection, only 2 or 3. The big one is maybe a foot in diameter.
 

MrAl

Joined Jun 17, 2014
8,989
Ahh! A Level Physics with Michael Nelkon. Those were the good ol' days.

Why don't you collect something like slide rules? They never run out of power.

Want to see my collection of slide rules?
Hi,

I have the tie clip one somewhere. It's an actual full slide rule too but is a tie clip size and actual tie clip.
 

MrAl

Joined Jun 17, 2014
8,989
I'm new to this site so be gentle with me please! I'm a 68 year old retired IT Manager with a passion for repairing and programming vintage HP & TI Calculators. I have in full working order an HP-41CX complete with numerous modules, printer and card reader which needs some TLC. I also have a couple of TI-59s, one permanently locked to a printer (key is lost) which work but both card readers need repair. I'm also a member of the Hewlett Packard Calculator Club (HPCC).
I'm currently trying to get an HP-97 to work which shows no sign of wanting to power up.
My degree is in Pure Mathematics and I've reached a point where I'm being hampered by lack of knowledge in both Electrical and Electronic fields. I've been searching the Net for free online Electronic courses, which is how I found this site. Can other members advise me of the best books/courses, either free or reasonably priced, to start an introduction into Electronics (assume all I have in that area is A Level Physics from 1966).
An example of what is frustrating me - the HP-97 Desktop Calculator (RPN) was the first machine I wrote business programs on in 1979. I've picked up an used one from EBay complete with case, power adaptor and 2 battery packs.
The power adaptor works (my friend tested it with a multi-meter) and gives out 8v AC ≈ and the battery packs should be 4.5v DC output. Of The 2 packs that came with the calculator, one is useless and the other although brand new in a box will not hold charge - it's 35 years old but new in box. I've got a brand new battery pack from the USA which should be with me in 2 weeks.
Reading the Service Manual it appears that you have to have a good battery pack as well as the power adaptor input, but once battery pack is fully charged you can then run 3-7 hours on battery pack alone.
What I want to learn and understand is the circuitry involved, what it does, why it does it and how to be able to trouble-shoot and fix a power problem like this. How to track from the adaptor power in terminals and battery terminals as to how far in the chain power is getting to the point where it fails. To find any components that are not working and to be able to replace them, basically electrical and electronic diagnosis. Any help and guidance would be appreciated.

Hi,

Sorry i cant help much without a schematic, but i had the old TI58 that i used for several years. When it finally gave up i called TI and they told me they dont fix them anymore (that was years ago).
Some time later i got a TI85 (yes flip the 8 and the 5 coincidentally). That i used for several years and loved it, then it died. Id love to get that going again. Then i got a TI89 and used that for a while but was put off because it would not do upper case alpha! Then i moved to the PC computer and hardly use hand held calculators anymore. Shortly after i created my own PC calculator that does advanced math and has a built in multi threaded C like language interpreter, and even solves ODE's using RKF45 (i know you know what that is :) )

The nostalgia :)
 

Thread Starter

Leviset

Joined Jul 9, 2017
6
Hi,

Sorry i cant help much without a schematic, but i had the old TI58 that i used for several years. When it finally gave up i called TI and they told me they dont fix them anymore (that was years ago).
Some time later i got a TI85 (yes flip the 8 and the 5 coincidentally). That i used for several years and loved it, then it died. Id love to get that going again. Then i got a TI89 and used that for a while but was put off because it would not do upper case alpha! Then i moved to the PC computer and hardly use hand held calculators anymore. Shortly after i created my own PC calculator that does advanced math and has a built in multi threaded C like language interpreter, and even solves ODE's using RKF45 (i know you know what that is :) )

The nostalgia :)
Hi,

Sorry i cant help much without a schematic, but i had the old TI58 that i used for several years. When it finally gave up i called TI and they told me they dont fix them anymore (that was years ago).
Some time later i got a TI85 (yes flip the 8 and the 5 coincidentally). That i used for several years and loved it, then it died. Id love to get that going again. Then i got a TI89 and used that for a while but was put off because it would not do upper case alpha! Then i moved to the PC computer and hardly use hand held calculators anymore. Shortly after i created my own PC calculator that does advanced math and has a built in multi threaded C like language interpreter, and even solves ODE's using RKF45 (i know you know what that is :) )

The nostalgia :)
Here is a link to a PDF of the Service Manual if you don't mind having a look at it.
http://www.decadecounter.com/vta/pdf/HP-97 Service Manual.pdf
 

Thread Starter

Leviset

Joined Jul 9, 2017
6
Any chance you have a link to an HP-35 service manual? I have two, one from the first production run and one from much later.

Thanks.

ak
If you have an HP-35 from the first run (which I think we're called Red Dot Big Bug!) then that's rare.
I've looked through all of my HP documents (16gb USB stick from HP Museum and 4 CDs from HPCC) and there is no service manual. I've asked on the HPCC forum if anyone has one or a PDF.
I have found a schematic at http://www8.hp.com/us/en/pdf/023hpjournal01_tcm_245_956440.pdf and I'll look for other links later
Deny
 

Thread Starter

Leviset

Joined Jul 9, 2017
6
If you have an HP-35 from the first run (which I think we're called Red Dot Big Bug!) then that's rare.
I've looked through all of my HP documents (16gb USB stick from HP Museum and 4 CDs from HPCC) and there is no service manual. I've asked on the HPCC forum if anyone has one or a PDF.
I have found a schematic at http://www8.hp.com/us/en/pdf/023hpjournal01_tcm_245_956440.pdf and I'll look for other links later
Denny
And http://www.keesvandersanden.nl/calculators/hp35_inside.php
Denny
 
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