Faulty Key on Aspire One.

servodude

Hi Guys

I have a D255-N55DGws that I like to break out for use when travelling insead of lugging about my large laptop.

Recently this developed a fault on the "A" key and only the A key

- this would be the case whether running Windows 10 or Ubuntu

- if I plug in an external USB keyboard the A works fine

I obtained a new replacement keyboard from ebay and installed it only to find that the same key does not work.

The ZIF connector for the cable looks to be seated properly.

I'm at a loss to work out whether this is a coincidence that the new keyboard arrived with the same fault as the old one, or whether there is a fault somewhere else on the laptop?

Does anyone have a link to specs for how these keyboards work (e.g pin out for the cable) and I could have a look at the signals on my scope or meter to work out what might be going one.

Or indeed any suggestions as to what might be the problem.

Kind regards,

sd

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HrVr000

Hi, can you send me pictures of flat cable end of keyboard and picture of connector(try angle from where is best to see "entrance where flat cable goes" and back of connector where are pins soldered.
this seems like one pin is not connected.

servodude

Hi

Thanks for the quick response.

I've tried to capture the images requested

- both with and without the flex cable inserted

Unfortunately I can't manage to get a shot inside the ZIF connector

- it does not look like there is any damage or that any of the pins are dry

- I'll try and give it a clean inside

Do you know what the pinout for this connector is?

- that might give me clues as to why only the A on two different keyboards might be failing

Thanks for your help.

Best regards,

sd

IMG_20160808_095738.jpg

IMG_20160808_095809.jpg

HrVr000

Hm, on pictures connector seems fine,

for "A" key, pin should be 2. from mark(2 from left), but that pin is also for "esc" key and "1" and x or c not sure few more...
is esc key working and caps lock?

servodude

Yes

- that's the strangest thing every key apart from the A works

- ESC, CAPSLOCK and all the keys surrounding the A are fine

I should hopefully be receiving a "replacement"-replacement keyboard in a few days to try; I suppose it's not that unusual that if they fail they might fail in the same spot.

If i knew how the keys were multiplexed out it would be able to rule out the chance of anythign else being the problem before this arrived.

Thanks for your help.

Kind regards,

sd

padgett

Exactly, each key is a matrix of signals, lose one line and more than one key will act up. Two different keysets would seem to rule out a keyswitch so try something supid: with the cursor ready hold down the alt key. Type 6 then 5 and release the ALT key. Did an A appear (is how the preceeding was entered) ? If not it is probably a software issue in the operating system & need to find a 15-year-old who knows how to trace Interrupts 10 and 16.

servodude

Good point

yes - I can use the ASCII codes

- enable NUMPAD (fn - F11)

- ALT-065

- ALT-097

give me upper and lower case A

so without any further info it really looks as though both the keyboards I have tried have failed at the same key?

all the best

sd

servodude

Hi

after receiving another replacement keyboard

and having gone at the connector with some compressed air

it now seems to be failing on a smattering of keys along the middle row. (A,F,G,J,L)

- which would make it look more likely that it's one of the lines that has failed

However I still can't see anything wrong with the connector itself

- it looks clean and everything mates neatly

- the soldering on it looks fine

- it's difficult to see where the tracks lead (I think they mighy go straight through the board)

Any other suggestions for stuff I might easily try?

Kind regards,

sd

HrVr000

Hi,

well I would try put some plastic (something thin or something solid but thin) on flex cable but not where pins are on top so flex will be little more pressured on pins, if that does not work I would try little hack I found out,
tools you need regular lighter.
to be clear not use butann lighter that burns in green or blue or something like that,
Pass 1 or 2 times on flex cable, not more as you will melt cable, and pass 1 time on top of flex where are pins, what will this do is plastic of flex cable will shrink and tracks will be pressured more (better connection) and when you pass on top of flex cabels (on pins) it will burn uncliness of graphite. After that pass with napkin pins on connector to clean it
cheers
. Hrvr000