[SOLVED] Laptop's keyboard replaced but it doesn't work ?

Oct 31, 2020
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Machine is a Toshiba Satellite C650 laptop. Orange juice was spilled on the keyboard, but it only killed a few keys. Other keys all worked. I removed the keyboard & washed it in warm water, dried it for a few weeks in a warm place. During this time I used a USB keyboard (the rest of the machine still functions perfectly, there was no run-thru into the case or MoBo).

When the keyboard was dry I reconnected it and dis-connected the USB keyboard - but no keys at all now worked, Nothing, could not enter bios or boot menu via keyboard.

Ordered a new keyboard and continued using the USBKB till it came. Connected the new KB once received, it did not work. Nothing. Compu still booted fine, but no internal KB input was working. Since it DNF even during boot/BIOS presumably its not an OpSys issue, its Hardware

Checked SETUP, nothiing there that would prevent keyboard working. Reset SETUP to defaults anyway, no joy.
Tried cleaning the new KB cable-end nd connector with alky. Nope.

Suggestions what to test next would be great appreciated. I know some people prefer an external KB on a laptop, but I strongly disagree.
 
Oct 31, 2020
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Cable or the connector on the motherboard is bad, or the replacement keyboard is bad. Not really a lot of things it can be but you can't check any of them without actually replacing the hardware.
Thanks for your input Hang-the-9.

I don't think either keyboard is bad: (1)The replacement is brand new, not 'used' so is most likely good. (2)The original keyboard should also be half-good - it was working partially before removal and I could trigger Setup/BIOS with it. Even washiing it shouldn't have done any harm, and it was thorughly dry before being reconnected.

MoBo connector is also not likely bad, since the original keyboard was partly working when removed. The cable-end clamp-clip on the MoBo connector is not visibly broken, and engages/disengages as expected.
There were no excessive-force events during dismantling and refitting the two keyboards tested, that could plausibly explain the sudden DNF of the connector. The keyboard cable connector on the Satellite is very accessible & straight-forward, does not require force and does not invite damage. The laptop does not have to be dismantled at all to get the keyboard off, it just unscrews and lifts off. So I can't see any chance for collateral damage to other copmponents either. This is a real puzzle to me.

My first thought was that connecting the ext KB had tricked the BIOS or PnP into ignoring the internal KB. But there is no setting in the BIOS Setup to control the keyboard selection except the "fast boot" option. However, the fast boot option is correctly set to 'off' for full hardware detection. I have tried removing the CMOS battery to erase any such possible hidden bias, and it did not help. I don't think its possible for such a bias to occur in the first place, nor to persist after clearing all settings. But it was worth a try.

The only thing I did that was unusual was that I operated the laptop for weeks without any internal keyboard in place.
I didn't think that could have caused any damage? The circuits would simply have been open.
But something has changed between removal and eventual replacement of the keyboard, and that seems to be the only unusual thing.
I am disinclined to buy another keyboard as a test device. Its fair to assume the brand-new one is good.

Does anybody else have any suggestions for testing or troubleshooting this?

If I was running Windows on this machine I would ask it to run a PnP search for new hardware (to see if it got detected), but I'm running Linux Ubuntu, and don't know how to ask it to do that.

If I used the cable from the old keyboard, wouldn't testing the wires for voltage give me some answers?
Would I need a digital tester for that, or can I use my vintage analog meter safely on it?

Puzzled.
 
Oct 31, 2020
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Cable or the connector on the motherboard is bad, or the replacement keyboard is bad. Not really a lot of things it can be but you can't check any of them without actually replacing the hardware.
This is a report on how this ssue was resolved. Someone may find it useful.
Hang-the-9 was correct, it was defective cable on the brand-new keyboard.
The cost was refunded by the seller, but since they did not want it back, I experimented by cutting the end of the cable shorter, a bit at a time. Once I'd cut about 2mm off the end, it worked.
Haywire, but WTH.
 

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