Ebook touch screen died slowly

[Ziguo]

Hi, I got a Tagus Táctil 2016 (a rebranded Boox C65) as a gift a year ago. This ebook worked fine for two months, but then the touch screen became a bit "too sensitive". Some months later it went the opposite direction; half of the screen became irresponsive. Now the only part working is 1/4 of the total area. Who gave me the ebook threw away the ticket, so no service support.

I have access to a nearly identical model, so I tried swapping the screen module and it works; it must be just the touch screen that is failing.

My main suspect is the Goodix GT9157 chip (data sheet attached) and the components near it, but the only thing I coud do is test them on the ribbon and all I know is that none of them are shorted.

I know that this is very difficult to diagnose and probably impossible to repair, but the fact that it didn't die suddenly but rather incrementally makes me think that maybe someone may have a clue.

Additional notes:

- The device was not exposed to direct sunlight, nor dropped, no water spills. Nothing.
- I have the other ebook I mentioned, but its screen is completely shattered. Its chip is different, though.
- I don't know how to safely disassemble the screen from the touch sensor sheet without breaking the e-ink glass.




The Goodix chip and its minions:

 

[davenn]

Hi, I got a Tagus Táctil 2016 (a rebranded Boox C65) as a gift a year ago. This ebook worked fine for two months, but then the touch screen became a bit "too sensitive". Some months later it went the opposite direction; half of the screen became irresponsive. Now the only part working is 1/4 of the total area. Who gave me the ebook threw away the ticket, so no service support.

I have access to a nearly identical model, so I tried swapping the screen module and it works; it must be just the touch screen that is failing.

My main suspect is the Goodix GT9157 chip (data sheet attached) and the components near it, but the only thing I coud do is test them on the ribbon and all I know is that none of them are shorted.

I know that this is very difficult to diagnose and probably impossible to repair, but the fact that it didn't die suddenly but rather incrementally makes me think that maybe someone may have a clue.

I suspect that it is more likely the actual touchscreen rather than the electronics that drive it ... 99% probability
Why, you ask ? ....
well, I work with a lot of electronics that have touchscreens. I see around 40 - 50 failures a year and it has always been the screen.

Dave

 

[Ziguo]

I suspect that it is more likely the actual touchscreen rather than the electronics that drive it ... 99% probability
Dave

Thanks. What is the most usual part that fails? The copper traces?
Also, is becoming irresponsive gradually a common issue?

 

[davenn]

Thanks. What is the most usual part that fails?

The actual screen

Also, is becoming irresponsive gradually a common issue?

yes

 

[Ziguo]

Ok. Thank you very much