Should I bother? HP-34C in rough shape

[Adam Vaughn]

Hello everyone. I recently came across an example of the HP-34C at a local antiques mall. It's in its original box, along with manuals, case, and charger. Unfortunately, the battery pack was left installed within the unit, and exhibits signs of major corrosion. The seller is asking $66 (40% off from the original $110 marked price), and I'm wondering if I should bother. What say ye? Thanks in advance!
-Adam

[Geoff Quickfall]

I would say yes to a complete package. In fact I would jump at it. I just restored a 34c but it involved bypassing the power flex circuit and hardwiring to PCA the power and charge wires plus making new battery tabs. Payed $30 for it not working and no box, case, manuals.

Fortunately the battery corrosion is situated far enough away from the PCA as to not damage it. It may affect the LEDs but these are easily replaceable with a donor 31e or the like. I think the box and manuals are worth the value.

I never see HP stuff in the local Vancouver flea markets or thrift stores :-(

[Paul Dale]

The box and manuals would be worth that much unless they are in poor condition. If the 34C works as well, it is a bonus.


Pauli

[Maximilian Hohmann]

Hello!

If you need it for your collection, go for it. The "30 series" were (in my eyes) the worst LED calculators HP ever made and it is almost impossible to find a working specimen which is in good cosmetic condition as well.

The batteries tend to leak inside the electronics which offer zero protection against it, the plastic used for the housing is brittle and much too thin. Many of these calculators have cracks in the housing an broken battery covers.

I guess that most owners threw their calculators away after a couple of years (together with box and accessories which makes them so rare) and went for an HP-11C or 15C instead which were cheaper and better in every respect - apart from missing that magical glow in the dark.

Regards
Max

[Geoff Quickfall]

The battery problems are affected by two things, both not necessarily HPs fault.

1. Battery size; width and length have increased by the manufacturers to augment battery life. This increase is now at the maximum dimensions (can't remember the agency in charge) and stresses the battery tabs on the 30 series. The original size were no problem. I lightly 'tap' the cathode nipple to shrink the length of the battery by a silly mm or two.
2. Owners that leave batteries in the calculators, watches, flashlights, palm pilots... are idiots.
3. opening the case by amateurs leads to cracked cases at the base of the calculator. The techs at HP were skilled at separating the shell.
   

The 34c was the first intro of the solver and had a nice size RAM for programs and were continuous memory. The display was larger and included 1000 radix and which was selectable between dot and comma. The keyboard snap is probably the best of all HP's. The down side were the first heavier variants with the floating ICs. At least you could swap ICs at the repair depot but over time the compression foam does not return, ie. press the keys into the PCA. Easily repaired by soldering them in place. The other nice thing from a repair point of view was the ability to swap ICs and LED block without desoldering. The second version, lighter had the ICs soldered.

Main problem about battery compartment size with newer oversized batteries are, as Max alluded to when he faults HP:

1. Broken battery tabs due to battery manufacturers increasing battery length and the low tolerance to accept these batteries.
2. Battery leakage due to neglectful owners which migrates into the calculator along the flex ribbon to the main PCA.
   

Battery tabs can be replaced but require you to be handy. The flex ribbon can be removed and the three traces can be hard wired to the PCA solving the flex ribbon problem.

So although they spice series seem problematic I would not blame HP. I like the 34c due to its memory, LEDs, size and key snap feel.

Geoff

[d b]

Adam; A 34C? Just buy it at that price and don't look back. You'll regret it if you don't.

Maximilian; Everything you said is true, but it's still an HP RPN and it needs a home. The only doubt is was it fried but; see Paul's post.

[Adam Vaughn]

Thanks for the replies. I don't have a 34C yet, though I do have a 31E. I had a bad feeling (and still do, really) that this amount of corrosion would be disastrous for the innards. I didn't attempt to remove the pack from the calculator, but it had lots of white crystalline stuff coming from both ends. Everything about the calculator seemed perfect until I removed the battery door. Fortunately, the unit seems to have been stored right-side up, so maybe there wasn't a whole lot of leakage into the unit from the pack, but I've heard that NiCd cells also tend to emit corrosive gases when they leak, so it might've gotten its licks in that way. In any case, I'll probably pick it up next time I'm there, assuming nobody else has bought it. If they have, c'est la vie.
-Adam

[Geoff Quickfall]

Check this out:

http://www.hpmuseum.org/forum/archive/in...-2111.html

Geoff

[Dwight Sturrock]

(04-14-2017 12:12 PM)Maximilian Hohmann Wrote:  Hello!

If you need it for your collection, go for it. The "30 series" were (in my eyes) the worst LED calculators HP ever made and it is almost impossible to find a working specimen which is in good cosmetic condition as well.

The batteries tend to leak inside the electronics which offer zero protection against it, the plastic used for the housing is brittle and much too thin. Many of these calculators have cracks in the housing an broken battery covers.

I guess that most owners threw their calculators away after a couple of years (together with box and accessories which makes them so rare) and went for an HP-11C or 15C instead which were cheaper and better in every respect - apart from missing that magical glow in the dark.

Regards
Max

The HP34C was my introduction to RPN, but like Max says they do seem flimsy and I did upgrade to a 15C as soon as they came out.

I took the batteries out and stored it until about 2008, used it for a couple of years at work with AA batteries, then I sold it. Didn't like the lack of an automatic "off" feature, along with the comparatively heavy current drain. Plus the LED display is hard for me to read since I started using reading glasses.

It was cosmetically good, no battery leakage, and sold with all the manuals and case.

[aurelio]

(04-14-2017 06:01 PM)Den Belillo (Martinez Ca.) Wrote:  Adam; A 34C? Just buy it at that price and don't look back. You'll regret it if you don't.

Maximilian; Everything you said is true, but it's still an HP RPN and it needs a home. The only doubt is was it fried but; see Paul's post.

Completely agree with both, but let me say also that the 30's are ones of the more beloved.
I don't understand the choice of the ribbon connecting solution, actually a Achilles heel for those machines, while I was surprised while opening my first model with the floating ICs.
They appeared for me, the first time here in italy more "serious" than the 20's series , maybe 'cause they seemed for me closer to the classical's shape, for size and colour... my "little" 25, compared to them, was a toy
But now after about 40 years, the toy looks like just out from the factory (except for the smoke of my father ), while you have just to look at the 30's overlays, to understand their age.

After these cosmetical thoughts let me say that the 34c was so unique for me (as Geoff reminds) for its solver.
Unfortunately I got my one, only quite recently and I like it so much, don't think too much to make it yours!

[SlideRule]

(04-15-2017 03:22 AM)Adam Vaughn Wrote:  Thanks for the replies. .. I'll probably pick it up next time I'm there, assuming nobody else has bought it.

PM sent

SlideRule

[Adam Vaughn]

Thanks again for the replies! Sorry for the delay, but things have been rather crazy around here as of late.

Anyway, I bothered..........

There's the box. Seems to be in pretty good shape overall, other than the number written in the top right corner.

Here's what you see when you first open the box:

Lots of stuff in there. Not quite sure what the cardboard insert is for, or where it's supposed to go.

The contents of the box:

Seems to be complete, including the cable tie for the charger cord. Also stuck in the box was the original receipt from Lechmere (a now-defunct chain of appliance/electronics stores) from 1981, for $129!

The front of the calculator:

Looks pretty good. Guessing it wasn't used a whole lot, or at least taken care of to some degree...

The back of the calculator:

Here's where the bad news starts to show through. Also, according to the serial number, it was made in Singapore in early 1981.

Battery cover removed:

There's the really bad news. Lots of gunk from both ends of the pack. Also, some bluish corrosion shows on the charger connector, and the battery door has a busted tab on that end, with a corresponding crack in the case.

Close-up of the leakage:

I have yet to try and forcefully remove the pack, for fear of causing more damage. Not quite sure as of yet exactly how to go about dislodging it if there's any hope of saving the contact card.

So yeah, it's quite the mess. That leakage is pretty nasty stuff as well; a bit of it managed to leak through the cover into the leather case. Should be an "interesting" cleanup/hazmat job, to be sure..........
-Adam

[pier4r]

What a pity. How can one save everything so well and then leave the battery inside. I could understand if it was thrown in a closet without order and then forgotten.

Moreover something that was not exactly cheap. $129 in 1981 are $360 now. So you paid one sixth of the original price more or less.

[Adam Vaughn]

(04-17-2017 08:45 AM)pier4r Wrote:  What a pity. How can one save everything so well and then leave the battery inside. I could understand if it was thrown in a closet without order and then forgotten.

Moreover something that was not exactly cheap. $129 in 1981 are $360 now. So for you paid one sixth of the original price more or less.

Yeah, it's a shame. I'm guessing someone used it a few times, put it back in its box, and forgot about it for 30+ years. The booth I found it at generally has a large number of pop culture items, along with some vintage electronics, usually fairly overpriced. Said booth does still have an HP-25, which I believe is priced at $62. It has the case and battery pack (which has not leaked nearly as badly), but none of the other accessories, and the model label on the front has taken some wear. I probably would've picked it up if I didn't already have an HP-25.

And yeah, I know I did pretty well price-wise, historically speaking. I'm not exactly sure why the original purchaser went with the HP-34C when they could've bought an HP-11C for not much more, with similar specs. Maybe they bought the 34C, then when the HP-15C came out a year later, the owner decided to upgrade one of those, and unceremoniously shoved the HP-34C in a desk drawer or something.

Getting back to the battery issue, does anyone have any ideas about what would be the best way to remove the old battery pack without doing much damage? Also, is there a good way to neutralize this crystallized crud? I've been doing my best not to touch it, but every time I handle the calculator, I make sure to wash my hands soon afterwards..........
-Adam

[Maximilian Hohmann]

Hallo!

(04-18-2017 06:12 AM)Adam Vaughn Wrote:  Getting back to the battery issue, does anyone have any ideas about what would be the best way to remove the old battery pack without doing much damage?

The damage is already done, there is not much that you can make worse now. The crystalline stuff is mostly electrolyte which is more or less harmless, but as it may also contain some traces of cadmium it is better to be careful. Wear rubber gloves and do not inhale any dust.
I would carefully scratch away the crystals using a wooden toothpick or plastic stick until there is sufficient clearance to pull the battery out. If some parts of the calculator remain attached to the battery they were broken anyway.
After that disassemble the calculator and clean all plastic parts with normal water. With the innards of the calculator it depends how far the electrolyte has already "traveled" along the PCB. You can immerse the affected end in distilled water until the electrolyte is dissolved, rinse and dry it. After that it depends on the amount of damage how much of Geoff's repair instructions will be required...
If the electrolyte has already found it's way into the display it is probably not worth to attempt a repair however.

Good luck
Max

[aurelio]

(04-18-2017 11:06 AM)Maximilian Hohmann Wrote:  Hallo!

(04-18-2017 06:12 AM)Adam Vaughn Wrote:  Getting back to the battery issue, does anyone have any ideas about what would be the best way to remove the old battery pack without doing much damage?

The damage is already done, there is not much that you can make worse now. The crystalline stuff is mostly electrolyte which is more or less harmless, but as it may also contain some traces of cadmium it is better to be careful. Wear rubber gloves and do not inhale any dust.
I would carefully scratch away the crystals using a wooden toothpick or plastic stick until there is sufficient clearance to pull the battery out. If some parts of the calculator remain attached to the battery they were broken anyway.
After that disassemble the calculator and clean all plastic parts with normal water. With the innards of the calculator it depends how far the electrolyte has already "traveled" along the PCB. You can immerse the affected end in distilled water until the electrolyte is dissolved, rinse and dry it. After that it depends on the amount of damage how much of Geoff's repair instructions will be required...
If the electrolyte has already found it's way into the display it is probably not worth to attempt a repair however.

Good luck
Max

Think positive, Adam, and don't worry too much...you 'll succeed to restore your calculator..
hold it upside down and try gently to remove the electrolite as much as possible; do it with a old paint brush ...(cut it on the top to make it shorter)
Then try with a wooden toothpick to discover the space between the battery pack and the plastic case, use it also to complete the work you have started with the brush.
using the toothpick try gently a leverage to check if the battery pack is still "attached" to the body or it moves, if moving the pack will drop on your table (cover it with old newspapers before to star the procedure, you will throw away with it all the dust).
I should avoid in this first step to use water (Maximilian will excuse me) for cleaning..
after completing the cleaning of the battery compartment we can check now the healt of the battery contacts on the machine (if they still exist, who knows) then you can try to open the calculator and the big mistery will be revealed (as Crazy Horse said to W.B. Hickok )

[dm123]

Hi all,

I am a long time owner of several hp calculators. I read an article on vintage calculators and was surprised to learn that my 15c has a sellers market for it. I have it and the original box , but want to keep it. I also found a 25c in my closet with carrying case. I also have a 12c. I also found a 34c in great condition. I hope you don't mind me hijacking the tread. I am posting pictures. As you can see, somehow, I knew not to plug it in without the rechargeable battery in there. I have a large post it note on there that I must have written decades ago. The rechargeable battery is corroded , but it did not corrode in the calculator. I must have taken it out a long time back. The 34c, box and manuals are all near mint.
I have pictures on my iPad but it won't let me post them as they are too large. Is there another place I can post them so that you can assess the condition of it.

Thanks

[pier4r]

You can use imgur.com and then use direct links. Also you can use the classified section of the forum.

[dm123]

Hi pier,

Thanks. I have posted the pictures at the link below. I haven't dusted the keyboard yet. This was right out of the box. Battery compartment is clean.

Does anyone know where I can buy a new rechargeable AA double pack for the 34C so that I can plug it in,charge it and test it out?

Thanks again. Here is the link

https://imgur.com/gallery/ZuU8K

[Maximilian Hohmann]

Hello!

(04-19-2017 06:22 PM)dm123 Wrote:  Does anyone know where I can buy a new rechargeable AA double pack for the 34C so that I can plug it in,charge it and test it out?

There is a seller on eBay USA (and occasional poster on this forum) who makes simple replacement battery packs for these - and other - vintage HP calculators for very decent prices. They are not as pretty as the original packs but with the cover back in place no one will see any difference. Apart from the fact that the replacement packs have 2...3 times the capacity of the original ones and won't leak as easily.

Regards
Max