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Dead key on 35s
03-12-2016, 09:58 AM
Post: #1
Dead key on 35s
The + key of my 35s is dead. I try to figure out if it can be fixed.
I searched for tear down pictures but couldn't find anything about the keyboard.
Does anybody know:
- what technology is used?
- is there a mean to fix it?

The calculator was not very much used and I have no idea why a defect appeared on the key which is not totally dead but would only respond to very hard push.
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03-12-2016, 11:41 AM (This post was last modified: 03-12-2016 11:41 AM by Maximilian Hohmann.)
Post: #2
RE: Dead key on 35s
(03-12-2016 09:58 AM)Tugdual Wrote:  ...I try to figure out if it can be fixed.

By pressing "CHS" and "-" instead ;-)

But joking apart: If you ask me, it's not worth getting fixed. This is not a high build quality calculator and certainly not designed with possible repairs in mind. And not a collectible either. Taking it apart and reassembling will take several hours, the result will probably not be pretty to look at and if one key already failed the next one is going to fail in a few days or weeks...

Regards
Max
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03-12-2016, 12:48 PM
Post: #3
RE: Dead key on 35s
(03-12-2016 11:41 AM)Maximilian Hohmann Wrote:  if one key already failed the next one is going to fail in a few days or weeks...

And what about the exponential distribution is memoryless distribution...?! Wink

Csaba
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03-12-2016, 01:02 PM
Post: #4
RE: Dead key on 35s
Have you found this?

https://www.flickr.com/photos/24544549@N...7690376071
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03-12-2016, 01:12 PM (This post was last modified: 03-12-2016 01:19 PM by Marcio.)
Post: #5
RE: Dead key on 35s
For quite some time I thought hardware problems on the 35s were a "rare" occurrence. Turns out it's not that rare. I read somewhere (maybe in these forums?) that at least 10% of all machines produced were faulty. Given that the vast majority of users are not as demanding as we are, I suspect this rate is actually a bit higher. And I am not even considering that the other 90% will eventually fail too.

Suggestion: If you like the simplicity of RPN programming and want an alpha-numeric display, get the 32sII (42s would be even better). It's of high quality, collectible, reliable, will last forever and not that expensive.
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03-12-2016, 02:46 PM
Post: #6
RE: Dead key on 35s
Thanks all for answers.
@Thomas, nice picture set; so apparently the keyboard is hidden below a white layer with what seems to be bumps? Terrible technology!

@Marcio, yes the 32SII looks like the plain simply I could use everyday but not that easy to find in Europe (as well as the 42S). So far I found a few coming from the US on eBay. Any other lead?
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03-12-2016, 02:57 PM
Post: #7
RE: Dead key on 35s
(03-12-2016 02:46 PM)Tugdual Wrote:  the 32SII looks like the plain simply I could use everyday but not that easy to find in Europe (as well as the 42S). So far I found a few coming from the US on eBay. Any other lead?

Uh?
Of all my 32Sii and 42S just one came from USA; the others were from Italy, Germany, Belgium...

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    Massimo

-+×÷ ↔ left is right and right is wrong
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03-12-2016, 03:02 PM (This post was last modified: 03-12-2016 03:03 PM by Marcio.)
Post: #8
RE: Dead key on 35s
(03-12-2016 02:46 PM)Tugdual Wrote:  Thanks all for answers.
@Thomas, nice picture set; so apparently the keyboard is hidden below a white layer with what seems to be bumps? Terrible technology!

@Marcio, yes the 32SII looks like the plain simply I could use everyday but not that easy to find in Europe (as well as the 42S). So far I found a few coming from the US on eBay. Any other lead?

Well, since there is no other option from HP with similar characteristics, I suggest you get a DM-41L from SwissMicros, which is very close to you.
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03-12-2016, 06:11 PM
Post: #9
RE: Dead key on 35s
Don't forget SwissMicros is working to recreate a 42s also!
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03-12-2016, 06:19 PM
Post: #10
RE: Dead key on 35s
(03-12-2016 06:11 PM)Dan B Wrote:  Don't forget SwissMicros is working to recreate a 42s also!

Sought after, the 42L might be their biggest seller.
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03-12-2016, 07:21 PM
Post: #11
RE: Dead key on 35s
(03-12-2016 06:19 PM)Marcio Wrote:  
(03-12-2016 06:11 PM)Dan B Wrote:  Don't forget SwissMicros is working to recreate a 42s also!

Sought after, the 42L might be their biggest seller.

Unless they come out with a 42P...
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03-12-2016, 07:38 PM
Post: #12
RE: Dead key on 35s
(03-12-2016 07:21 PM)Steve Simpkin Wrote:  
(03-12-2016 06:19 PM)Marcio Wrote:  Sought after, the 42L might be their biggest seller.

Unless they come out with a 42P...

;) :)

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03-12-2016, 08:14 PM
Post: #13
RE: Dead key on 35s
(03-12-2016 02:46 PM)Tugdual Wrote:  Thanks all for answers.
@Thomas, nice picture set; so apparently the keyboard is hidden below a white layer with what seems to be bumps? Terrible technology!

Indeed, the pictures do not show the key domes on the PCB.
These domes are not that bad and are in line with other HP machines made in China from that era.

From your description, I believe that the problem lies in the plastic key itself: Each key has a small pin that can be bent or broken or smashed due to unknown reasons.

If you take the time to open your 35S (you need to break a number of plastic rivets in addition to undoing the tiny screws), you may check this issue for other keys as well.

If this is the case, the repair should not be that difficult. Basically you may just glue the bent pin using fast setting epoxy adhesive like Araldite.
If the pin is totally smashed, then you need to make a small pin from a similar plastic material. I would not use metal pins as these may cause damage to the domes in the PCA.

If not, have a look to the key domes and use a can of compressed air commonly found in electronic shops to clean any eventual residues.

Also it is important to check if there are signs of liquids that may have been dropped over the keyboard, specially sugar drinks.

The same epoxy adhesive can be used to fix the PCA against the plastic rivets.
Great care must be taken to ensure that the adhesive does not leak into the key domes underneath while doing this!
That is why fast setting adhesive (5 minutes) must be used.
When doing this, I put a small quantity of adhesive on a small group of rivets, let is set for 5 seconds, then turn the machine upside down for another 5 seconds and keep doing this for a couple of minutes until the adhesive stops moving. Then repeat the procedure for the next group of rivets until done.

It requires a lot of care and patience but it pays in the end.

As I see it, this is not that cheap calculator by any means. Prices goes around 60 Euros+s&h mark in several places including eBay.

For comparison, a cheap calculator would be a CASIO CLASSWIZ fx-991EX or their regional variants (for my region that would be a fx-991SPX Iberia) costing about 22 Euros around Europe.

Jose Mesquita
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03-12-2016, 09:07 PM (This post was last modified: 03-12-2016 09:08 PM by Tugdual.)
Post: #14
RE: Dead key on 35s
(03-12-2016 08:14 PM)jebem Wrote:  
(03-12-2016 02:46 PM)Tugdual Wrote:  Thanks all for answers.
@Thomas, nice picture set; so apparently the keyboard is hidden below a white layer with what seems to be bumps? Terrible technology!

Indeed, the pictures do not show the key domes on the PCB.
These domes are not that bad and are in line with other HP machines made in China from that era.

From your description, I believe that the problem lies in the plastic key itself: Each key has a small pin that can be bent or broken or smashed due to unknown reasons.

If you take the time to open your 35S (you need to break a number of plastic rivets in addition to undoing the tiny screws), you may check this issue for other keys as well.

If this is the case, the repair should not be that difficult. Basically you may just glue the bent pin using fast setting epoxy adhesive like Araldite.
If the pin is totally smashed, then you need to make a small pin from a similar plastic material. I would not use metal pins as these may cause damage to the domes in the PCA.

If not, have a look to the key domes and use a can of compressed air commonly found in electronic shops to clean any eventual residues.

Also it is important to check if there are signs of liquids that may have been dropped over the keyboard, specially sugar drinks.

The same epoxy adhesive can be used to fix the PCA against the plastic rivets.
Great care must be taken to ensure that the adhesive does not leak into the key domes underneath while doing this!
That is why fast setting adhesive (5 minutes) must be used.
When doing this, I put a small quantity of adhesive on a small group of rivets, let is set for 5 seconds, then turn the machine upside down for another 5 seconds and keep doing this for a couple of minutes until the adhesive stops moving. Then repeat the procedure for the next group of rivets until done.

It requires a lot of care and patience but it pays in the end.

As I see it, this is not that cheap calculator by any means. Prices goes around 60 Euros+s&h mark in several places including eBay.

For comparison, a cheap calculator would be a CASIO CLASSWIZ fx-991EX or their regional variants (for my region that would be a fx-991SPX Iberia) costing about 22 Euros around Europe.
Thanks Jebem, very comprehensive description, which somehow discouraged me to even try especially if I would need to break plastic rivets (I saw that also on the pic set). The calc didn't get any liquid, may be it was pressed in a bag which is the only possible explanation I cant think of after a defective malformed keyboard.

Just wondering, is the 15C LE using the same technology? So far this is the best keyboard I have and now I'm worried it might follow the same path.

Also agree with you, this calc. is not cheap; I didn't care too much for the bugs but a defective key is simply more than I can bear.
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03-12-2016, 09:17 PM
Post: #15
RE: Dead key on 35s
Various owners of the 15LE have reported keyboard problems. They even started a failure rate analysis.
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03-12-2016, 09:39 PM
Post: #16
RE: Dead key on 35s
The 15C LE keyboard is ok if you're lucky to have one w/o residue from the production process. Unfortunately the timeout after a keypress is too short, i.e., in rare cases a keypress is registered twice. Another problem of the emulator.
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03-12-2016, 09:47 PM
Post: #17
RE: Dead key on 35s
(03-12-2016 09:39 PM)Thomas Radtke Wrote:  The 15C LE keyboard is ok if you're lucky to have one w/o residue from the production process.

I guess the same applies to the 35s. Owners have reported all kinds of complaints regarding keyboard issues. As for the 15LE, which uses the same hardware as the new 12C, just read the 1-star comments for the 12C on Amazon and you'll see how low quality these new machines are. Reviewers have reported display issues too, with pictures.
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03-12-2016, 09:59 PM
Post: #18
RE: Dead key on 35s
(03-12-2016 09:07 PM)Tugdual Wrote:  Just wondering, is the 15C LE using the same technology? So far this is the best keyboard I have and now I'm worried it might follow the same path.

I would say the chinese manufacturing plants are using similar technologies for these calculators, be it a 35S or a 12C or a 15C LE.
Basically they use the same technology that Texas Instruments have patented long time ago in the 70's with one or another variant.
They use metal domes over a PCB matrix and cover the domes with a sticky plastic film.

I know that you are not willing to open your 35S, but if someone does (like myself when I'm in the mood for it), usually the key register failure common causes comes down two a couple of reasons (excluding the usual failures caused by the end users):
- The plastic key cap pin gets bent/broken/smashed even with careful usage;
- the area under the dome is contaminated with residues from the manufacturing plant.
The later cause is getting more frequent than the former, if the reports we can read here and elsewhere are to be believed (and I do believe because I have found this flaw myself).

See here this report on a HP-15C LE. For me it is a exemplar situation where quality control has space for improvement in those manufacturing plants.

And the SwissMicros recent series had the same keyboard failure caused by residues if my memory is not betraying me from what I've been reading in these forums here.
Luckily these issues with SwissMicros were promptly fixed by the owners by just following the manufacturer instructions on how to clean the contaminated domes (or else got swift replacements from SwissMicros).

Jose Mesquita
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03-12-2016, 10:08 PM
Post: #19
RE: Dead key on 35s
(03-12-2016 09:47 PM)Marcio Wrote:  I guess the same applies to the 35s. Owners have reported all kinds of complaints regarding keyboard issues. As for the 15LE, which uses the same hardware as the new 12C, just read the 1-star comments for the 12C on Amazon and you'll see how low quality these new machines are. Reviewers have reported display issues too, with pictures.
I'm under the impression the 15C LE has a very good hardware but a terrible firmware, but I might be wrong of course. With the exception of maybe some 50g, all in all there are no acceptable HP calculators past the Pioneers.

I always come back to my 32SII :-).
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03-12-2016, 11:03 PM
Post: #20
RE: Dead key on 35s
(03-12-2016 02:46 PM)Tugdual Wrote:  Thanks all for answers.
@Thomas, nice picture set; so apparently the keyboard is hidden below a white layer with what seems to be bumps? Terrible technology!

@Marcio, yes the 32SII looks like the plain simply I could use everyday but not that easy to find in Europe (as well as the 42S). So far I found a few coming from the US on eBay. Any other lead?

The 32sII is a terrific calculator, but 0, 3k makes me cry. IIRC, the 15c is 448bytes, almost ten years before.

Although the keys of a a pioneer are fantastic, I'll invest a little bit more in a 15c. And it is landscape Smile

Cheers

JL
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