ipad air 4th doesnt working touch

[khj]

Hi guys.
My ipad air 4th doesnt working touch.
I replaced display but cant fix it. I think the reason is mainboard.

I can hear some noise sound at this parts (i upload the picture)
It is shield so i cant check now.

What is the reason? Bad cap is the reason that touch is not working?

[Stevedb]

Re: ipad air 4th doesnt working touch

Mostly filter or so is blown, you change digitizer?

[khj]

Re: ipad air 4th doesnt working touch

I changed lcd + touchscreen

[mon2]

Re: ipad air 4th doesnt working touch

What is the history of this iPad? Why was the display replaced?

On at least one iPad model, the connection from the A10 CPU to the digitizer ic becomes disconnected at the BGA ball level. It is a well known pcba defect. The fix is to review the diode mode readings of the SPI bus connections used by the digitizer ic. The diode mode test will confirm if the SPI line is open or not between the CPU and the digitizer ic.

Next, the A10 CPU has to be removed and reballed and then soldered back to fix this dry solder connection. Check some YouTube videos on this topic. We had a similar case with the ipad 7th gen. See the great video by Ayman in Egypt for the process details. We replaced the digitizer ic first and the touch did not return. Before this, we checked the diode mode readings of the digitizer ic.

To date, we do not know if the A10 CPU used on the iphone is the same or not for the iPad. Lim in Malaysia has a video on the same fault and he briefly mentioned that if the A10 is replaced, then the serial number changes. No idea on how to fix this issue if the A10 CPU is replaced.

Start with the simple check if loose inductors on the board. Post details on this iPad.