Lenovo Yoga 3-1470 80JH Keyboard issue

[kalemaroni]

Customer dropped their laptop and I replaced the screen. They came back with it a few days later saying the keyboard wasn't working properly.

When typing slowly it's fine but if you type fast it misses certain keys randomly.

I bought a new keyboard and that is doing the same. Is it coincidentally a bad replacement keyboard or can there be a motherboard issue that can cause this problem?

I can do board repair so if there are any values that you want me to measure I'll provide the info.

Many thanks in advance.

[mon2]

From internet searches, the Yoga 3 = NM-A381 logic board ?

Found the schematic for NM-A381. The keyboard scanning is performed by the IT8386E-192 CX LQFP-128L device @ UE1.

These parts are often with an embedded 8051 microcontroller. The clock source for this component and very likely the internal microcontroller appears to be an external RTC clock crystal with the value of 32.768Khz.

See attached.

Confirm this clock crystal is stable for the ITE device. Perhaps reflow the supporting parts for this clock source.

From the symptoms, appears that the clock to drive the keyboard scanning is off since you have replaced the keyboard itself. Other than this, consider to reflash this ITE controller but personally do not have this experience, yet.

@SMDFlea is the pro in this field.

[SMDFlea]

Originally Posted by mon2

From internet searches, the Yoga 3 = NM-A381 logic board ?
@SMDFlea is the pro in this field.

I`m no pro just a hobbyist. To program the EC he will need a special programmer such as a Vertyanov JIG ,SVOD3/4,RT809H