kobo aura hd touchscreen suddenly stopped working

[akamaus]

Hello,
After charging my kobo aura hd device I found start menu not responding. I decided something got wrong with flash memory, so I disassembled the device, extracted the flash card, checked it with fsck, badblocks, all works. I googled and found there is a hard reset combination (light-button + power-on). Looks like original image was restored, at least I saw a screen asking to choice a language. But it still doesn't respond to touches.

I found similar thread https://www.mobileread.com/forums/sh...h+stop+working but it's for aura h20 device. They say sensor should only work with bezel closed. Is it relevant for kobo hd?

Any ideas what might went wrong and what to try?

[davidfor]

The Aura HD uses IR for the touch sensors. The screen needs to be correctly positioned in the bezel for the touch to work. So, putting it back together properly is needed.

[akamaus]

unfortunately it still doesn't work even when assembled.

By the way, what's the IR? Infrared? According to wikipedia infrared touchscreens have an array of IR LEDs and detectors on the perimeter of screen, and I don't see any. Just a screen with some protective glass covering it. Case is just an empty plastic box. Although front cover has some black plastic layer from inside which is bent towards the screen on the perimeter. But looks like it just for dust protection.

[davidfor]

Yes, "IR" is Infrared. There are emitters around the edge with detectors on the other side. Part of the bezel is transparent to IR and either the emitters and detectors poke up into that, or the bezel guides the IR beams. If the bezel, screen and emitters/detectors are not aligned properly, the beams won't be in the correct place and the touch won't work.

[akamaus]

Any ideas how to diagnose the exact problem? Should emitted radiation be visible for smartphone camera, for example? It seem to be able to detect IR pulses from TV remote controller.

My kobo is rather old, from 2014, so warranty is void long ago and I dont like the perspective of throwing it away...

I saw there're screens sold on Ali for it. But I'm not sure whether replacing it would help or not.

[Ken Maltby]

As David mentioned, it's all in the alignment and uninterrupted IR transmission through the special black plastic that is attached to the "front cover"/bezel. Make sure there is nothing between the IR transistors and the scalloped edges of the black plastic. Some have had a piece of black tape move in the way. It doesn't take much to cause a problem there, even some tape glue residue could disrupt the IR beams. I have had to repeatedly clean the black plastic to get my touchscreen working one time.

Luck;
Ken

[ksiflhjla8]

You just saved me from throwing away my kobo because of non-working touch

[kabole]

Is it possible to buy new bezel?

I replaced broken screen, but found two small cracks on the bezel, which appeared during dismantling. As result, touchscreen not working, message "Water on the screen" present all the time.

I didn't fixed bezel and frame by glue, but tried all possible positions - touch screen not reply.

Somebody has experience to order new bezel? Thank you.

[ksiflhjla8]

two small cracks shouldn't be able to destroy the functionality?

[Quoth]

It could if interrupting any beam.

[Ken Maltby]

Originally Posted by ksiflhjla8

two small cracks shouldn't be able to destroy the functionality?

The smallest disruption to the IR path is enough. Think of a cracked mirror, the image around the crack is drastically changed, even if the crack is itself small.

Luck;
Ken