Some of the keys did work easy fix I thought ordered a new keyboard same thing I thought maybe new keyboard is defective but it does it on the same keys there are about 12 that do not work I tool it off again cleaned all contacts same thing
First, did you if the problem disappears when
testing with an external USB keyboard, to make sure that the problem is hardware and only concerns the native keyboard?
Second,
is your keyboard connected through a ribbon or not?
Ancient 14" DELL Latitude (like Dell E6400, E6410, E6420, a.s.o.) where not using ribbons. More recent models may be connected through ribbons.
Third,
is your "new" keyboard really new, or a an untested second hand one, which is possibly defective?
Fourth, what about the seller reliability?
Sometimes, sellers think that a laptop model is compatible, but it is not because the pinout is different, despite the keyboard has same form factor. Try to check if other sellers are more restrictive in models compatibility.
In case your keyboard is using a ribbon / flex cable:
- If for both the old and the new keyboard
you have been using the same ribbon, first think I would do is to perform a
conductivity check on all stripes of the ribbon. If your multimeter hasthe continuity check feature, your probes at each extremity of each wire in the ribbon and see if the multimeter beeps.
- If
you have been using different ribbons, with a thin toothbrush
clean the ribbon socket on both sides, i.e. at rear and
also inside.
After a minor liquid damage (due to a rainy weather), I have seen vertdigris migrating from the rear to the inside of a ribbon socket.
Even a small deposit that contacts two ribbon tracks, or that prevent good contact of a track with the socket can generate stange failures.
- Then, I would
welder again all contact points at the rear of the socket, preferably with leaded solder, which is more ductile and easier to work.
- You can also
check that your ribbon is sufficiently pinched at both ends. If necessary, add some thin adhesive to make it a little thicker.
-
Unplug the touchpad for your tests, or plug another touchpad. Often the keyboard and the touchpad work "together". A defective touchpad may result in had to diagnose keyboard behavior..
- Under a macroscope,
carefully check if the motherboard has some vertdigris. Check both sides.
Clean it, both sides, with a thin toolbrush and isopropyl alcohol (isopropanol).
- Lastly, you could perform
continuity checks using a multimeter on components (e.g. capacitors) near to the keyboard socket.
Hope this helps.
