Survey of HP35s Owners


I would like to take a survey of HP 35s owners. If you own an HP35s, please indicate the number of units you have and if you experience keyboard problems in the form of missed keystrokes. I'll start.

(1) HP35s with keyboard problems


(1) HP35s without keyboard problems

- Pauli


[1] No keyboard problems.


(2) copies. An occassional missed key on the one I leave at work when I type too fast. I'm not sure if it happens only when the "b"usy annunciator is on, or just randomly. I also don't recall if it's a particular key. Just have to be careful.

Edited: 17 Mar 2008, 8:02 p.m.


(1) HP35s without keyboard problems so far


(1) HP35s S/N 72104039
I experience frequent problems with numerical entry, possibly because I try to go too fast.

The most irritating problem is apparent double entry with the R/S key. This causes a program to start and then stop before finishing.


(1) No keyboard issues encounted to date. I even tested it many times with the flight mach number equation on page 106 of the HP67 owner's manual. This is a really good test in my opinion - if you can do it in under 50 seconds.

I cannot say the same for the 49g+, despite setting the KEYTIME to various values.

Jeff K.


2 units, no problems.


One (1)
No Problems at all.


2 units. No problems.


1 x HP 35s -- no problems, except one or two missed keystrokes total; medium-duty use overall.



(1) No keyboard problems in general; still misses to register if busy when a key has been hit even though you could feel the click;


1 calculator, lightly used, and no key problems


One unit, no keyboard problems at all


(1) No keyboard problem - lightly used


1 unit, collectors item, rarely used. No problems so far.

I'd like to add my new 17bii+ to the list: It misses some keys regularly.

Edited: 18 Mar 2008, 5:41 a.m.


1 Unit, not in frequent use, no keyboard problems.


one, no problems so far


One, no serial number (preproduction), secondhand, unknown amount of use/abuse by previous owner, I've used it heavily for article writing/testing, no problems so far. Still in the batteries it came with after many months.

Best regards from V.


First unit, keyboard problems with "4" and ENTER key. Replaced under warranty; new unit has a soft gold arrow key out of the box and has already displayed some keyboard problems with decimal key.


I own 1 HP 35s, I have never had a missed keystroke or other keyboard related problem.


[1] HP 35s, no keyboard problems noted, but not heavily used.



1 HP35s.

Light use, no keyboard problems.


(1) Just starting to have the very occasional problem with the "." and "0" keys, but if I try to reproduce it, it goes away after a few tries (almost as if the key contacts clean themselves from repeated use).



Stefan, that's exactly what I see. The one key in my 1st calc where you could sort of repeat it was the ENTER key. If I pressed that key off center I could sometimes reproduce the problem. I could sometimes reproduce it on the "4" key too but not as easily. Most of the time the keystroke would be missed but not reproducible on the next keystroke.

I wonder sometimes if this is partly mechanical and partly electronic, namely a polling issue as some have surmised. Maybe I should just go back to using a slipstick and/or abacus. ;-)


When I get a chance, I'm going to try speeding up my HP 35s to see if the problem goes away. If it's a polling issue, it might.


When I get a chance, I'm going to try speeding up my HP 35s to see if the problem goes away. If it's a polling issue, it might.

And if it is a switch contact bounce problem, it might get worse.
The speed up is an experiment worth trying.

-- Richard


(1) HP-35S with keyboard problems from day one.


(1) HP-35S with some problems with the '.' and '0' key, but quite always after I turn it on; the problem seems to vanish after a while.

And for further missing keystrokes, I guess it's my fault: too fast in typing!

-- Antonio


1 unit, no problems at all, a pleasure to use.


One unit, no keyboard problems.


I have 1 unit, no keyboard problems.


I have one 35s - NO (keyboard)problems at all

I think It's a great calc. Good looking and best quality compared to other brands.


(1) with no problems.


(1) HP35s, light use, no problem so far, some keys feel/click "softer".


1 unit, no problems. So far, it seems to be a reliable unit.


1 HP 35s. Immediate problems with the ENTER key.


One (1) with no problems so far. First batch.


(2) Both units are fine, no keyboard problems.


Well, I suppose that I ought to chime in...

I purchased one HP-35s, S/N 721xxxxx, which has experienced no problems.

I later received another HP-35s at the 2007 HHC Conference, S/N 734xxxxx, which has had some problems missing strokes of the "0" key.

-- KS


(1) HP35s with keyboard problems.

In my case it is defintively a problem related to the system/firmware as the calculator seems to hang when I do fast additions. It does not seem to be a physical problem with the keaypad.

That's why I no longer use it. I won't buy a second one after the known bugs get fixed.

Edited: 20 Mar 2008, 2:55 p.m.


Brand new 35s, s/n 7430xxxx, keyboard defective. "4" key requires heavy pressure, loud click, does work, needs to be returned [overall keyboard feel not consistent but wouldn't be a problem w/o "4"]. Also "down arrow" has surface ripple moulding flaw.


I tried HP's recommended fix (coins in the battery slots), and I have noticed that the problem (so far) is much better. It had been missing the decimal key very frequently, but I haven't had it miss the decimal key since the "repair". I had a lot of programs in it before, but now only have 2 and 1 equation. I wonder if there is some relationship to that.


[...] coins in the battery slots [...]
Has this procedure been posted here in detail? How is that supposed to work? Sorry if I overlooked it, I'm really interested (although mine hasn't had such problems yet).



This is what HP recommended that I do:

Remove the batteries, and place a small coin in each battery slot, such as a U.S. dime or penny. They said that would get rid of any built up static charge that could be causing the problem. I'm just a humble structural engineer, so I have no idea if HP's suggestion makes any sense, but I decided to try it. I put a relatively untarnished U.S. penny in each batter slot, and kept them in there over night. Of course all of my programs and equations were lost.

After I did that I noticed much improvement, but time will tell if this works in the long-term.

I have also adjusted my style of keying in numbers, which used to be quick stabbing of the keys. I have tried to slow up and push them more firmly. My old keyboard style never gave me a problem with my HP's that were made in Singapore and the USA.

The following is me going off on a tangent: In my judgement my HP11c (made in the USA) is the most sturdy calculator that I have, compared to my 32sii's, 42s, 33s, and 35s. I started my career with it, and I wouldn't be surprised if I retire with it.

Two (2) without keyboard problems

3 units, 1 unopened. both work wonderfully with no keystroke problems.

I own one HP 35s, SN CNA7460XXXX. No keyboard problems at this time, but I do not use this calculator heavily. Most of my work needs straightforward aritmetic, so I use a solar-powered Casio (it does have sci functions which occasionally get used).

The build quality my example of the HP 35 is pretty good. The only problem is that the serial number sticker is applied off center and crooked. Makes me wonder about the innards...

The only problem is that the serial number sticker is applied off center and crooked.

that sticker is as easy as to take off and stick it back properly; I don't consider this a problem, took me 10 sec to fix mine

1 HP35s, "7" key required heavy pressure until I turned evil and violent. Since then, it works ok.

HP35 SN:1143A38138 (still has arctan anomaly) No Keyboard problems. Have owned it since it was new. Cost over $400 with extra battery and charger(was a lot of money back then). Delivery was long, agonizing months.
The 10 place trig functions were a lot better than the heavy Peter's function look-up tables.

[1] HP 35s, daily use, occasionally miss a keystroke (say about once every 2.0 weeks). It is usually when I'm rapidly running through some semi-lengthy calculations.

Note: I have found that I am able to carefully depress ANY key on the keyboard BEYOND the "trademark" click, and if I carefully stop short of bottomming out the key, it will miss the keystroke every time. That is a design flaw in my opinion. The ONLY reason for the familiar HP click is to undeniably confirm a keystroke. The design should be such that it is impossible to achieve a click w/o registering a keystroke.

That's my 1.98 YEN (2 cents $U.S., at the current exchange rate) ;)


There are a couple of keys on my 35S that I can fool into giving me a "Click" without registering a keystroke. It is difficult, but it can be done.

Despite my best efforts, I wasn't able to get a "Free Click" from a co-worker’s 48G.

My 50G has an issue along the right side of the keyboard. It is the worst on the backspace key. I don't need to try to fool it at all, in fact to register a backspace I need to ask very nicely.

Even with it's quirks, I like the 35S and hope HP keeps working back to the keyboards of old. I am very impressed with it's usability. For my day to day use, it packs just enough punch,

Very respectfully,


Add me to the list. I have a 35s and it misses enough keystrokes that I've abandoned it and now use my trusty 48G for all but trivial calcs. One thing that stinks is that the problem seems to have gotten worse.

(1) HP-35s that I'd like to throw out the window.

Enter zero in all the registers and try the following calc:
4 ENTER 3 x 6 / (but press the last three very fast)
It'll miss the 6 every time and return 0.0000 (0/12).

Do the same with 1's in all the registers and you get 0.0833 (1/12). Done with 2's will give you 0.1667 (2/12). etc...

None of my previous HP's did this (32sii & 33s). I think that it's a serious flaw that HP need to fix.

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