Just bought a HP-67 calculator at an auction

[mipidc]

I just purchased a hp-67 in pristine condition. It looks like it has never been used. The problem is that it did not come with a charger. Any thoughts on how to test this calculator? I would also like to test the magnetic tape reader as well. I've included a couple of photos of the calculator.
The serial number is 1611a02046 and the earliest known serial number as I have learned about begins 1609 so this was made in the 11 week of 1976 and is one of the earliest units produced. Any more information about this unit would be greatly appreciated. It came with two mint condition manuals as well.    

[Namir]

You can buy a charge on eBay. They are available now! You will also need to buy new batteries for it. eBay's waterhosko is the guy to buy them from. He even sells USB cables that power up the calculator!!! Check his auctions.

As for the magnetic card reader, it is most likely need repair because the card reader deteriorates with TIME, regardless of how pristine the calculator looks. There are a few people who can fix it. You can ask for folks on this web site.

Namir

[Thomas Okken]

I bought a used HP-67 on eBay several years ago. I had the card reader repaired and bought a battery holder so I can run it using standard AAA alkaline batteries. I got the battery holder from eBay seller waterhosko, and the card reader repair was performed by eBay seller jones.sebago.lake. I'm happy, the calculator has been working perfectly ever since.

[Maximilian Hohmann]

Hello!

(07-29-2020 12:27 AM)Thomas Okken Wrote:  ...and bought a battery holder so I can run it using standard AAA alkaline batteries. I got the battery holder from eBay seller waterhosko, ...

I also have one of his AAA adapters. A very smart invention :-) It works very nicely with recharcheable AAA cells. A modern NiMh cell typically has a cpacity of 800 or 1000mAh which is twice as much as the original cells had. Plenty so to say. And you don't need the original charger at all. But you could still use it and even charge the cells inside the calculator. And here comes the usual reminder: Although the HP-67 is not as easily killed by connecting it to a charger without batteries installed than his smaller "Woodstock" siblings (which will die instantly) it is a good idea not to attach the charger at all. Ever.

"Waterhosko" can also provide you with the replacement "gummy wheel" parts required to fix the card reader. They are penny items. But don't attempt to perform the repair yourself unless you have the necessary skills. Here (on this very site!) is a good set of instruction of how it can be done: https://www.hpmuseum.org/cgi-sys/cgiwrap...i?read=179 Decide for yorself if you are able to do it.

Regards
Max

NB: "Waterhosko" is an active member of this forum (his latest post is less then a week old). You can contact him through this forum regarding battery packs and parts. This is how I got mine.

[Harald]

(07-28-2020 11:43 PM)Namir Wrote:  As for the magnetic card reader, it is most likely need repair because the card reader deteriorates with TIME, regardless of how pristine the calculator looks.

Namir

Well, if the card read has NEVER been used, maybe there is a chance it still works. I suspect the deterioration of the wheel is triggered by contamination. Maybe it gets contaminated by the cards, but maybe just air getting in is enough. Would be interesting to find out...

[rprosperi]

(07-29-2020 11:20 AM)Harald Wrote:  

(07-28-2020 11:43 PM)Namir Wrote:  As for the magnetic card reader, it is most likely need repair because the card reader deteriorates with TIME, regardless of how pristine the calculator looks.

Namir

Well, if the card read has NEVER been used, maybe there is a chance it still works. I suspect the deterioration of the wheel is triggered by contamination. Maybe it gets contaminated by the cards, but maybe just air getting in is enough. Would be interesting to find out...

Interesting comment Harald! I have seen a few people over the years assert that their 67 card reader works, never having been repaired. Though somewhat suspicious that it was more likely they were simply unaware of the repair, this theory would explain it. It would indeed be interesting to know.

It's interesting that this problem, common to all old HP (and TI) machines, remains pretty much unexplained, other than the overly simple "the rubber eventually turns to goo", which is not something commonly happening to other similar vintage products. My cassette deck has bands and capstans with rubber 'wheels' which may have hardened or gotten brittle, quite the opposite of turning to goo. I'd like a materials science engineer to comment if this is really typical or perhaps a unique phenomenon.

[Paul Berger (Canada)]

My TI-59 has never had the drive wheel replaced and the card reader still works fine. I have had four HP 97s and at least six 67s go past me and every one of them has required replacing the drive wheel.

[SlideRule]

(07-29-2020 12:38 PM)rprosperi Wrote:  It's interesting that this problem, common to all old HP (and TI) machines, remains pretty much unexplained, other than the overly simple "the rubber eventually turns to goo", which is not something commonly happening to other similar vintage products. My cassette deck has bands and capstans with rubber 'wheels' which may have hardened or gotten brittle, quite the opposite of turning to goo. I'd like a materials science engineer to comment if this is really typical or perhaps a unique phenomenon.

The fuel-cell 'sealant' used on the F-111 would consistently 'revert'; kept the fuel barn at RAF Upper Heyford gainfully employed. Perusal of REVERSION STUDIES OF NATURAL AND GUAYULE RUBBERS {DTIC A-A257 501} is a start on understanding the many causes of 'reversion' in rubber, plastic, etc compounds.

BEST!
SlideRule

[Maximilian Hohmann]

Hello!

(07-29-2020 12:45 PM)Paul Berger (Canada) Wrote:  My TI-59 has never had the drive wheel replaced and the card reader still works fine. I have had four HP 97s and at least six 67s go past me and every one of them has required replacing the drive wheel.

Same here and not to mention several HP-41C card readers all of which have "liquified" card reader drive wheels. BUT I also happen to have an HP-65 with a working original untouched card reader. It may depend on how the calculators were stored during the last forty years.

Regards
Max

[toml_12953]

(07-29-2020 12:45 PM)Paul Berger (Canada) Wrote:  My TI-59 has never had the drive wheel replaced and the card reader still works fine. I have had four HP 97s and at least six 67s go past me and every one of them has required replacing the drive wheel.

Same here. My TI-59 is working perfectly after over 40 years of use.

Tom L

[mipidc]

Thanks everyone for the info. This is a great venue! I did go ahead and ordered a battery pack from waterhosko. I should get it in a day or two. I will let you know if it works. Even though I probably won't use it, does anyone know of where I can get a mag strip to test the reader? Based on the responses it will be interesting to find out if it works!

[rprosperi]

Yeah, OK, "all" was too harsh... There's no question that many fewer TI-59s had the roller failure than HP's (though I've seen a TI gummy wheel repair kit, so not all), suggesting perhaps TI used more than 1 material for them. My typical luck was a unit that was bad. I also recall more than a few fellow students in the late 70's having card readers that failed in their 59s while still only 1-2 years old, though clearly not from the same type of failure.

As there seem to be some original units still working, environmental conditions over extended periods sure seem to be a likely suspect.

I'll read the article SlideRule posted, maybe there's some hints.

For the units you guys assert are still working and original, how do you know they're original? Have you owned them all along?

[teenix]

(07-29-2020 11:20 AM)Harald Wrote:  Well, if the card read has NEVER been used, maybe there is a chance it still works. I suspect the deterioration of the wheel is triggered by contamination. Maybe it gets contaminated by the cards, but maybe just air getting in is enough. Would be interesting to find out...

Hard to say. HP says it had to use a "special" polyurethane compound to provide reliability over many operating factors, so it may degrade at different rates to other polyurethane types. I don't know much about chemistry but it appears these can degrade due to many factors including temperature, location (sea-side etc) and residue or hungry little microbes which might get transferred from your fingers to the cards to the wheel.

Maybe if the calculator survived packed in its box in a cool and dry environment over the years, the wheel might still be ok.

cheers

Tony

[Maximilian Hohmann]

Hello!

(07-30-2020 01:03 AM)rprosperi Wrote:  For the units you guys assert are still working and original, how do you know they're original? Have you owned them all along?

Unfortunately I have not owned a single HP classic all along. No way to afford them back then... Regarding my working HP-65 the original state is an assupmption based on the untouched state of the back label. It could of course have been repaired by HP themselves early when they still had a supply of new labels.

Regards
Max

[Dave Britten]

I'll echo the recommendation to not buy a charger. Get one of the excellent 3xAAA packs from ebay, buy a nice NiMH smart charger, and get either a set of Eneloops or high-capacity NiMHs.

DON'T attempt to charge NiMHs inside the calculator, as they can overheat and melt the plastic. Running it on NiMHs is perfectly safe.

[mipidc]

I did buy the battery pack with three AAA batteries and it worked like a charm! Thanks again for the advice. I'm waiting for the mag card reader repair guy to send me a mag card so I can test to see if the reader works. We will see!

[mipidc]

Ok, I just received blank mag cards I bought off of eBay. Since I'm not familiar with programmable HP calculators can anyone suggest the best way to test if the mag card reader works? Any thoughts are greatly appreciated!

[Thomas Okken]

The simplest test is to write a program to a card and then read it back again. Writing a program to a card is done by sliding the W/PRGM - RUN switch to the W/PRGM position, and inserting a card into the lower slot on the right side of the calculator, magnetic side down. (Make sure to use a card that does not have the write-protect corner cut off.) If the program in memory is more than 112 lines long, it will not fit onto one side of a card, and the calculator will display Crd to prompt you to insert the other side of the card, i.e. turn the card 180° while keeping the brown side facing down.

To verify that the program is read back in correctly, turn the calculator off and back on to completely clear its memory, slide the W/PRGM - RUN switch to the RUN position, and insert the card. Just like when writing, the calculator will display Crd to ask for the other side of the card if the program is more than 112 lines long. After reading, switch to W/PGRM as use SST to step through program memory to verify that the program was loaded correctly.

[Moggul]

(08-22-2020 09:06 PM)mipidc Wrote:  Ok, I just received blank mag cards I bought off of eBay. Since I'm not familiar with programmable HP calculators can anyone suggest the best way to test if the mag card reader works? Any thoughts are greatly appreciated!

The first test is just tro try to slide the card from the right side. Insert the card in the right slot and push it gently. If the card is pulled correctly through the slot then you know the motor and roller work and then you can proceed to test as Thomas suggests.

If the card isn't pulled through the slot then you know you needto repair the card reader. Most 67s this age need the wheel or the shaft repaired or both.

[Chr Yoko]

This "gummy wheels" issue seems to come from the material degradation over time.

Looks like HP has chosen the wrong material and process : Low spec material and/or too cheap process that "forgot" some key steps in order to save on cost.
Typical short cut is avoiding the long post-curring / post-vulcanization step that would link the polymer chains together. Post-Vulc needs to put the parts gently aligned onto a stainless steel tray into an oven for long hours at a specific temperature with a specified ramp-in/out (depends on material compound, part size, geometry ...).

Rubber materials are diverse and some advanced rubbers, if used properly, can survive very severe environmental conditions such as acidic, basic, oils, petroleums, solvants, water , high temps, low temps .... Of course a "one size" fit all does not exist and you need to select the most suitable material for your application and to its cost target since some will cost you well over 100€/kg (FKM-FPM or Silicon for instance).

Look at your engine bay and you will see plenty of long lasting engineered application specific rubber materials ;-)

FYI, i just changed the handlebars grips onto an old MtB because they became overly sticky and we all know about those "ruburized" plastic housings for electronics that also become sticky over time (some computer mouses or keyboards for instance...).
One hypothesis is that those be-material parts can't be post-vulcanized or they would melt the underlaying thermoplastic during the process, so the rubber ends up decaying after a while and under human acidic fluids contact !