HP Forums

Aloha all,

I haven't been active with the museum or my calculator collection for about 15 years and see a lot of things have changed (Like having to create a new account ;-). All very exciting! I do have to admit that I'm a bit bummed that if I had dug some calcs out a few months ago I could have gotten a 41-CL board, and I wish I had known to buy a 35S when they were in production and cheaper, but I'm always late to the party. I started collecting in 96/97, and I was late to the party then. I will acknowledge I was lucky enough to get some of the remains from Educalc before it was all gone.

On the topic of repairs, I started pulling calculators out of storage boxes looking for one I could use for the amateur radio exams, and I discovered that the vast majority didn't work. I have quite a lot of calculators. I did discover that the 42S is actually fairly nice.

So I've got a 45 and 65 (and likely a 35 when I find it) that will need some love, only one of my woodstocks works, none of the spices I tried work, all but one of my unboxed 41's don't power up. I expect most or all card readers will need a rebuild. I haven't tried any of my voyagers except my original 11c from college which thankfully powered up. Basically it appears anything I've used in the last 5 years works, and the rest don't. None of my TI's I tried except for an original TI-30 seem to be working. The clamshells I have tried are working.

What this means is that when I get time I'm going to be trying to resuscitate (I'm guessing here) on the order of 20 HP calculators from various product lines. I have the HP-41 repair manual from the calculator store, I know about the repair section here in the museum, and I know about the old forums, and a few things I've found in the new forums.

Has anyone assembled a comprehensive document for doing repairs across all the models in the various product lines? I got fairly close to having one of everything way back when, which means I'm going to be dealing with a lot of variations. If such a document exists I'd love to use it, else I'll do my best to document my repairs as I go along with whatever resources I find.

And for what it's worth, I'll likely be doing the same with another 20 TI calculators ...

In case you hadn't guessed, this project will probably take a while. But I fondly remember when I got my first ever 41CV from another fellow at microsoft, and I'd write little programs for it before going to bed and I'd sleep great. I won't say "sleep like a baby" because I have a new one (baby) and I slept way better than that. Since my wife and I are just getting started on our family I'm pretty sure I won't be doing any sort of assembly line repairs on calculators. However, I'm really sure that each time I bring a calculator back to life, I'm gonna sleep great!

Mahalo

I think Geoff Quickfall was doing a manual but not sure where it ended up.

I have a Classic Notes document with some info in it that might be of use.

Plenty of help here as well.

Still like to see a dedicated Repair section on the Forum :-)

cheers

Tony

(05-06-2022 01:21 PM)teenix Wrote: [ -> ]I think Geoff Quickfall was doing a manual but not sure where it ended up.

Yep, we've been waiting for THE BOOK for far too long... ;-)

(05-06-2022 01:59 PM)Massimo Gnerucci Wrote: [ -> ]

(05-06-2022 01:21 PM)teenix Wrote: [ -> ]I think Geoff Quickfall was doing a manual but not sure where it ended up.

Yep, we've been waiting for THE BOOK for far too long... ;-)

There's a rumor that Geoff went to extraordinary pains to create the entire COVID Panademic, in order to have a good excuse to not release THE BOOK, but most folks don't believe that. Most, that is...

Aloha,

I did see teenix's <a href="http://teenix.org/ClassicNotes.pdf" target="_blank" rel="nofollow">Classic Notes</a> page, and that's the sort of thing I'd like to see referenced in a single documents. I've seen multiple deep dives like this referenced, but no single source.

During Covid my old company got everyone a "home office improvement gift". Since I was in upper management I got the giant glass whiteboard. It's still not up. Nearly all the engineers got a scope. I should have taken the scope!

I'm certainly not going to question Mr. Quickfall's not delivering something, I'm getting the idea this is a somewhat large undertaking. I just figure it's not that much extra work to document bringing my babies back to life. And anytime I've done something like this in a professional context the extra 10% of time always has an outsized payback on team productivity. I learned early in as leader to always put the newest person in charge of the team knowledgebase. Always saved me a lot of time not answering questions, and avoiding having to say "I don't know, go find out and put it in the KB." Thus the illusion of omniscience is preserved. :-)

I must admit, it was quite disheartening to dig out my boxes of calcs and find that *NONE* of my complete in box near mint 20's and 30's were working. I knew 2 or 3 41's would need attention (one even has the green cancer on the battery contacts), but *all* of my most prized calculators? Ouch.

I forgot to add, I really want to express my deep appreciation to Dave for all the effort he has put into the museum. I've been coming here since he first appeared on the web. Creating a community and resource like this and to keep it vital and growing for 25-ish years is absolutely amazing. In one of my boxes is an old CD set and probably a bunch of other things I would never have known about if not for Dave and the Museum. Truly a great achievement.

Mahalo ala nui Dave, and to everyone who has contributed over the years.

(05-06-2022 02:17 PM)rprosperi Wrote: [ -> ]

(05-06-2022 01:59 PM)Massimo Gnerucci Wrote: [ -> ]Yep, we've been waiting for THE BOOK for far too long... ;-)

There's a rumor that Geoff went to extraordinary pains to create the entire COVID Panademic, in order to have a good excuse to not release THE BOOK, but most folks don't believe that. Most, that is...

WP43S is probably going to win the race, close, but still no cigar. :D

TheCalculatorStore in Spain has published a book about HP41 repair.
They are also selling different parts to help repairing the 41s.

(05-06-2022 04:19 PM)Didier Lachieze Wrote: [ -> ]TheCalculatorStore in Spain has published a book about HP41 repair.
They are also selling different parts to help repairing the 41s.

Good book, great store. Multiple orders to the US and I've never had a problem.

-Bill

(05-06-2022 02:48 PM)DrewNicholson Wrote: [ -> ]I must admit, it was quite disheartening to dig out my boxes of calcs and find that *NONE* of my complete in box near mint 20's and 30's were working. I knew 2 or 3 41's would need attention (one even has the green cancer on the battery contacts), but *all* of my most prized calculators? Ouch.

Hopefully you knew that you MUST NOT ever plug the power adapter into a Woodstock (20's) or Spice (30's) model without a known-good battery pack installed, or you will 95% surely damage the chips on the board due to crappy power supply design. It's best to never plug in the AC adapter at all as even a loose battery can lead to such damage.

If you did this, it's not 100% guaranteed that you killed them but it is quite likely. Try using charged AA flat-top NiCD cells, it's possible they are still OK.

If this did happen, they can sometimes be salvaged by replacing the damaged chips (generally from the same model) or you can replace a bad ACT (like the CPU) with a modern replacement from PANAMATIC, details are here:

http://www.panamatik.de/html/hp_calculat...r_kit.html

(05-06-2022 11:48 PM)rprosperi Wrote: [ -> ]Hopefully you knew that you MUST NOT ever plug the power adapter into a Woodstock (20's) or Spice (30's) model without a known-good battery pack installed, or you will 95% surely damage the chips on the board due to crappy power supply design. It's best to never plug in the AC adapter at all as even a loose battery can lead to such damage.

Sadly, I did not know this, at least not to this degree. But if I killed them, it was 15 or 20 years ago. I was using rebuilt battery packs, but there's no knowing at this time.

Hopefully nothing much for the majority of them but a bit of corrosion, even the lubricating goo under the power switch sometimes hardens and may limit power flow. Maybe just a bit of wiggling on the circuit boards might clear some corrosion up on the pins that connect the boards together. I've come across this in the past.

Unfortunately this all means opening them up, and trying to preserve the quality of the back label is an extra task to do. Warming the label with a hairdryer can help soften the glue. It only needs the top corners peeled enough to expose the screws - which, if you like, can be left out to keep the label in tact for future repairs.

Some of the capacitors may have deteriorated with lack of use over the years.

Check here for Tony Duels calculator circuits.

These might help you check the power supply voltages if you have access to a multimeter, although a scope is a better tool if you get access to one.

cheers

Tony

(05-07-2022 12:57 AM)teenix Wrote: [ -> ]These might help you check the power supply voltages if you have access to a multimeter, although a scope is a better tool if you get access to one.

Tony, since you brought it up, what have you got for a scope, probe, and logic analyzer? I've got a salae laying about somewhere here at home and my trusty wavetek meter (I couldn't convince myself to spend the $$$ for Fluke), but no scope. The screenshots in your doc look like a 3 channel Rigol?

FYI: I started out as an embedded engineer and my last job was running an embedded team. "Having" to open up my calcs to repair them isn't actually a deterrent. More like "fun". When I get going on my amateur radio set up I might have to buy other test equipment. Oh noooooo! :-)

And the HP calcs are old enough I don't think I have to worry about the surface mount components being smaller than I can handle.

(05-07-2022 03:03 AM)DrewNicholson Wrote: [ -> ]Tony, since you brought it up, what have you got for a scope, probe, and logic analyzer?

RIGOL MSO1104 4 Channel with 16 channel Logic adaptor.

cheers

Tony

(05-07-2022 05:18 AM)teenix Wrote: [ -> ]RIGOL MSO1104 4 Channel with 16 channel Logic adaptor.
Tony

Thank you Tony!
That looks like a nice rig! I will probably get one like it at some point.

On the repair front, I plugged a TI-58 into a PC-100C printer and it worked! Two other TI's did not, and a similar printer did not, but seeing these two items working together gives me hope that the majority of the calculators have simple board rot. Only one shows definite signs of needing a new ACT. I'll probably upgrade at least one ACT failure with each variety of boards from Panamatik, and I'm enough of a purist to really want to get them all working in original form.

I'll end up documenting each one separately I think.

Drew