hp35s missing keystrokes


Up until recently, my HP 35s rarely missed a keystroke. Now, the frequency of missed keystroles seems to be increasing. Has anyone else noticed this behavior? Most offten it is the decimal key, but I notice it with all of the numeric and the enter key. My impression is that sometimes the calculator lags in registering a preceeding keystroke. I have tried slowing down, but this has not solved the problem. Since going back to my 42s, I have has no problems at all.

My key punching style has not changed, and I've been using HP clacs since 1988. I've only had problems with the 33s, and now sadly, the 35s. My 35s has been my daily use calculator since the beginning of August 2007.


I too noticed this behavior with the "0" key, from time to time; I hope this will not get worse!

-- Antonio

(I am already in the verge of considering HP a failure: I don't need another excuse).

Edited: 1 Feb 2008, 4:41 a.m.


Hello. Some users have reported the same problem. I am one of them. Sometimes my 35s misses keys, sometimes it doesn't. It don't know why.

On all my other HPs (those built before the 49G), there is absolutely no problem.

Because of the keystroke problem, my 35s lies in a drawer and it is almost never used. Maybe the dustbin would have been a better place for it.

My 32sii is happy as I use it daily.


You mention the HP-32SII which I have seen many of and work well (never got to use one very extensively). But it's predecessor the hP-32S had major keyboard failure. I had two units where the rightmost column of keys stopped working!!!

Sounds like KINPO's quality control issues is Pushing OUR BUTTONS!!!


Edited: 1 Feb 2008, 10:16 a.m.


My collection is quite restricted. Concerning the 'oldies' I just have a HP 97, a HP 41C and a HP 41CV. The not so old ones are a HP 42s, several 48GX (2 of them new and never used) and several 32sii (4 of them new and never used, the brown ones ;) ). I never owned the 32s, but I have heard of the problem you describe.

I am so happy that several years ago, I bought all the 48GX and 32sii I could find in my area, just before they disappeared in the shops. Right after the discontinuation I sold some of them on e***. With the money I earned, I managed to finance my current 'backup-stock'.

Nowadays I understand why those people paid the double or even the triple price for a new 32sii. It simply is a wonderful calculator, with almost all the (useful) features of the 35s, and above all without those annoying bugs and a decent hardware. I will never give mine away ;)

And to be honest, as long as HP doesn't manage to build a new calculator with a very basic feature, the ability to register keys flawlessly, I will not buy a new one.



AFAIK the non-working key columns are _not_ a problem of the key contacts themselves nor the matrix,

it's rather a problem of the pcb interconnections, like those between the main pcb and the display.

Similar faults can be seen with early HP-38G and HP-48 units,

when the interconnection material shrinks, and contact fails as consequence.

This kind of contact problem even existed on the HP-41 series:

The (in-)famous 'zebra stripe',
and also the pressure-based battery contact block:-/

I think they include these time bombs by purpose, else the calcs would last too long;-)




Yep, me too. I don't know why, but I didn't notice any missed keystrokes for a little while after buying it. Now it happens so often that a fairly high percentage of my calcs have these. I don't know if it's because I've gotten faster or what, but it definitely misses them. I missed one calc a couple of times in a row and actually video recorded the calc (talk about ubernerd, LOL) and sure enough, I could hear a definite click, but nothing got to the screen. Slowing down is a bit better, but I think it still misses some even then.

A pal has borrowed my 48G, which served me flawlessly for 10 years. As soon as his new calculator gets here, my 35s will be used only for very limited calcs. This is VERY disappointing because I think the 35s is about as elegant and handy as any calculator can be.


I was an early fan of the 35s, but I have now gotten rid of both of them. Sent the unopened one back to HP, sold the other one on eBay.

Actually, I never had the keystroke problem mentioned. I just decided that I like my Pioneers better than the 35s. My 32sii has the same solver as the 35s (35s added only a very few functions), and the same fraction mode.

Turns out the only advantages the 35s has is more memory, algebraic mode, and the 2-line display.

But for my uses of this particular model, the 32sii memory is sufficient (if just barely). I prefer my 27s for algebraic calculating, and as for the 2-line display, well the 27s has one, and I still like the 32sii better even with a single-line display.



This is very disapointing to me too, because I really liked the 35s. I have a lot of good structural programs based on the AISC in it, I like its ability to handle fractions, and I really like equation mode and the solver. On the other hand, since I design structures for a living I need a dependable calulator, so I will probably go back to using my 42s.

I have tried slowing down and pressing harder, which seems to help, but not cure the issue.

I hope that I can get through the next 25 years of my career with my older HP's because of RPN. I can't stand using an algebraic.

HP, please get it together. Please find a better manufacturer. I won't even dare to suggest making something yourself because I know I will be laughed out of this forum. Funny how my cals that were made in the USA and Singapore seem to work without flaw, although one is 22 years old (HP 11c).


Noone dared to investigate the problem any further by taking the keyboard assebmly apart?


My HP-35s has the keystroke problem.

The keystroke problem really slows down my data entry. I have nearly always used machines with keyboards I can trust. So I could punch the keys on those machines and not worry about checking the display. With my HP-35s, as with my old TI-30 and TI-55II, I have to take some time after each quantity is punched in and check the display to see that the key strokes really entered.

I have two HP-33s calculators. Neither had a keystroke problem.

I have four HP-41's. None of them have keystroke problems.

I have about 25 other HP's ranging from the HP-35 through the HP-17B-II. I can't recall whether they have had problems or not since I have only used them occasionally.


I have one 33s and sometimes it misses the "0" key even if my speed is quite moderate. Also the keyboard is rock hard.


I bought two HP-35S--one had the missing keystroke problem. I called HP right away and told them about it. The person on the phone told me he'd never heard of a keyboard problem on the HP-35S, but would promptly take it back and refund my money (I bought it directly from HP).

The problem I had was the "+" key would sometimes not register. My other HP-35S is fine, however, so I don't know...a bad batch maybe? All I know is that it does happen.



I sent an e-mail to HP about missing keystrokes on my 35S on Tuesday (2/12). I got a call from "HP Calculator Support", who asked me to send it back to them for 'evaluation and possible replacement'. What was curious was I got the same old story that their "e-mail system is down", hence the phone call to my e-mail query. Does HP have continuously dead e-mail systems? This got me curious.

The person I spoke to asked me to send it back to HP Calc Support in Beaverton, OR. I found out who's at the address I sent it to via a Google search. As I suspected it's not HP that is handling the
warranty work. The outfit is called Stream:


No wonder their "e-mail is down". HP just passes the info to these guys and they take it from there. HP has nothing to do directly with customer calls for calculators. It all makes sense now as to why everyone here always get the same garbage answer
that "email is down".

And of course, the customer service rep I spoke to said they'd never heard of complaints about the keyboard issues. I let the guy know that several users I'm aware of DO have problems.

The guy said it would take 15 business days to either get my old calc back (if they find "nothing") or get a new one. What was also interesting is I was to send the unit back to the attention of one person in particular, named Aaron.

I think the only way to get HP to fix why we're having missing keystrokes is anyone who has an inkling of a problem is to call HP and gripe; given enough complaints they'll realize there's a defect somewhere. There must be a design flaw in this calc for so many people to have this problem. I sure will not be nice if they say "no problems" and will demand they fix or replace my calc.


Isn't that always the case? You have to gripe first. I hate it, but that's the way things work with their technical "support" group; it leaves you no choice.

I first wanted an exchange, but the person also gave me the spiel about five to ten business days (i.e. two weeks) before someone could evaluate what was "wrong" with my calculator and exchange it if something was wrong. This did not include the time I would lose sending it in. As if I were some idiot who couldn't figure out how use a calculator correctly. Anyway, since I bought two, and it was within the warranty period, I asked them to give me a refund.

The lucky people who don't have this problem with HP probably think I'm just whining.

Can't help that.



No, John, not at all; however, I fear HP might.

These days there is a trend among companies to "profile" customers according to complaints. There was a case of women barred from shopping at Filene's basement because of what the company thought was chronic complaining.

I wonder if HP has a similar policy.


Hi Brian. I haven't noticed any missing keystroke problems with my 35s (s/n 734). I wonder if the problem could be associated with early production batches.




My early 721 still registers all keystrokes quite fine.


It's really troubling that the problem seems so random. I ordered mine as soon as they were available, and I wondered if many units from early in the production run would have trouble. My s/n is 725.


I have the same problem with mine, but it's the "Enter" key and the 4 occasionally. The Enter button would be most noticed since it used so much. I hear the click but it doesn't register.

One thing I have noticed on missed keystrokes is it happens when I hit the key off-center. That implies some kind of mechanical issue. I haven't contacted HP for a repair/replacement. With the number of people who complain on this board, I'd bet a replacement has the same issue.

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