Question

Certain key combinations have stopped working

Jan 6, 2020 8:10PM PST

A month or so ago, certain key combinations have stopped working. What I have found so far is

left ctrl a
left ctrl z
left ctrl x
right shift z

To be clear, for example, right ctrl a works find. And left ctrl everything else not listed works fine.

I am up to date on windows update and have run MalwareBytes. I have restarted in safe mode, but the problem persists.

Any suggestions?

Windows 10 Home 1909 build 18363.535
Asus laptop TP41OU

Post was last edited on January 7, 2020 12:54 AM PST

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Comments
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Answer
To sniff this out
Jan 6, 2020 8:56PM PST

We try an external USB keyboard as well as a boot to safe mode or a boot to another OS. It does sound like a bad keyboard but more testing is required.

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...
Jan 7, 2020 12:53AM PST

Well, I don't think it is a physical keyboard problem because left ctrl s works just fine. So the shift key and ctrl key work just fine in other combinations.

I did try in safe mode and the problem is still there.

I will try to find an external keyboard. That will only prove it's not a physical keyboard problem, correct?

I will also try to create boot media to load a different os.

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Given the matrix method a keyboard uses.
Jan 7, 2020 9:00AM PST

You can't make that assumption. It's also why we test with the items I listed.

Sorry if I shortchange you here but how PC keyboards work takes a lot of background and data which I can't type for each time this comes up. The safe mode test adds to the certainty it's hardware.

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OK, may be a physical keyboard problem
Jan 8, 2020 6:19AM PST

>Sorry if I shortchange you here
No, no, not at all. I'm so grateful for your help.

Quite accidentally, the "broken" key combination worked. once. Imagine my surprise. If I repeat enough times, sometimes, I can get them to work.

So what does that mean? Why would the right shift not work with "Z" but work with every other letter?

I've tried forcefully blowing into the keyboard. Don't have any compressed air.

Sorry I haven't been able to set up booting to a different os or find an external keyboard yet. I'm on the road.

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Contacts in the keyboard
Jan 8, 2020 8:08AM PST

Can wear or get contaminants. At the shop we replace a lot of keyboards every year. The actual keyboard costs from 11 to 99 USD and the replacement work can take as little as 2 minutes on some models.

If folk want us to repair their existing keyboard we decline since we can't warrant such attempts. No one I know does that sort of work. And yes, there is some trade in key tops, but that's about it.

I take it that you declined to do the USB and other OS tests which are where we can be sure of the issue.

-> Your finding about repeating the key press adds value to the diagnosis it's just another failing keyboard.

I was going to look up the cost of the keyboard but I couldn't find your model.

Example: https://www.asus-accessories.com/laptop/tp410/

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will test with external keyboard as soon as I can
Jan 8, 2020 8:28AM PST

>I take it that you declined to do the USB and other OS tests which are where we can be sure of the issue.
Sorry I wasn't more clear. I'm traveling at the moment in a remote area (but with internet) so I don't have access to a usb keyboard. I tried to download an ubuntu iso, but the cellular data just couldn't handle it.

>Can wear or get contaminants.

I'm still not clear how wear or contaminants could cause the shift key to not work only for the Z key.

But I agree that from all the other signs it looks likely it's a physical problem.

Thanks!

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"still not clear"
Jan 8, 2020 8:36AM PST

Sorry but a full blown discussion about PC keyboard design and how they work is not something I will type into a reply. You could start research into that if you wish but you did add fuel to the bad keyboard diagnosis with your reply above about pressing it enough times.

Remember that this is a switch matrix that is scanned and more. I hate to write this but once in a while a client wants a full course (or classes) on electronics, how things work and more. We try to be gentle about that would be costly as we would charge the full repair rate by the hour to do that. Such doesn't make sense on 100 buck repairs.

I wish I had the exact model number but you can research how much a keyboard is along with a search on YouTube on replacing this model's keyboard to see if it can be done by everyday techs or users.

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thanks
Jan 13, 2020 4:47AM PST

>Remember that this is a switch matrix that is scanned and more. I hate to write this but once in a while a client wants a full course (or classes) on electronics, how things work and more.

Nope, wasn't asking for that. But I take it that the answer is yes, a key can be broken in combination with one key and not another. I did look up keyboard matrix and it sounds complicated.

The model number I gave in the OP was inaccurate because the o is really a 0. So it should have been TP410U. Looks like they are available.

Thanks for your insight.

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Ahh, that explains why I didn't find that model.
Jan 13, 2020 10:59AM PST

IS THIS THE FRENCH KEYBOARD?

https://en.accessoires-asus.com/grey-azerty-keyboard-laptop-for-vivobook-flip-63486-62159.htm#tp410ua|l finds it and the price.

This appears to be the more expensive system where you replace the top which includes the keyboard.

You could chance it with Ebay such as:
https://www.ebay.com/i/254392643362?chn=ps&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&itemid=254392643362&targetid=538495491015&device=c&mktype=pla&googleloc=9031354&poi=&campaignid=6470552634&mkgroupid=81274458647&rlsatarget=pla-538495491015&abcId=1139336&merchantid=101684599&gclid=CjwKCAiAx_DwBRAfEiwA3vwZYoMwo9xoqZgreeFgf4svJ3XbkZvTEgKNLRFunfYX9ZA7t_2VtMcOhRoCh7EQAvD_BwE

Sorry if this seems hard but there are varients of the keyboard out there so the language of the model would have to be known.

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Life is hard, eh?
Jan 13, 2020 4:08PM PST

Yes, from the research I did it does appear that there are slight varieties with the keyboards.

No, it's not the French model.

The ebay one looks correct just seeing the keys and shape. Is it correct that I won't harm the computer if I try to install a wrong variation.

I've also found an Asus authorized repair shop in the city I am moving to. I guess they will be more expensive.

Again, thanks for your help!!

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"Authorized repair"
Jan 13, 2020 4:42PM PST

I've found that to be very expensive OOW (Out Of Warranty.)

In my city there's the 150USD counter or base fee.
Parts look to be 150 since it's the top piece showing the the FRU parts for sale. FRU = Field Replacement Unit.

As to the harm, sorry but I've repaired so many PCs over the years and while this repair is a little more advanced it doesn't look particularly onerous. That is, I'd give myself generous time of 1 to 2 hours so I move slowly and document as I go. That is I pull out my cell phone to take a picture of cables, screws and such so I have something to refer back to if I need to.

You can get a preview of the underside of the top you'll be removing at https://www.ebay.com/i/223629093301?chn=ps&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&itemid=223629093301&targetid=541453976292&device=c&mktype=pla&googleloc=9031354&poi=&campaignid=6470552634&mkgroupid=81274458647&rlsatarget=pla-541453976292&abcId=1139336&merchantid=113602761&gclid=CjwKCAiAx_DwBRAfEiwA3vwZYq6-VnmlFrnt7qpwtUuwQ-EenRY311clsZova-YHNSJsS5_T7vTHDxoCEtIQAvD_BwE

This picture specifically:
https://i.ebayimg.com/images/g/hN4AAOSwgvVdWwVY/s-l1600.jpg

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All that is super helpful
Jan 13, 2020 6:32PM PST

Thanks for all that. I hadn't thought about the fact that if it's out of warranty then no need to go through an authorized dealer.

Thanks for all you help.

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