Kindle Fire 1st gen, absolutely no touchscreen response, it's frozen - Page 1
Forum section: electronics / repair

author: ivan747
author_rank: Super Contributor
timestamp: February 22, 2015, 01:48:22 am
content: Hi guys, I wanted to ask anybody with experience on capacitive touchscreens about this:Before trying anything, I wanted to ask you if you have had an experience with capacitive touchscreens that do not respond, and specifically, the case of the Kindle Fire 1st generation.More than a year ago this Kindle started to develop a problem in which it registered touch events when there weren't any. Sometimes I would touch the center of the screen and also get input on the corner of the screen, for example. After this, it began to miss touches in a section of the screen. Eventually, one day it decided not to get any input at all. When I bought it it was always a bit too sensitive.So I charged up the battery to roughly 50% and stored the thing for a long while. Now I kind of want to use it again. I have tried plugging and unplugging the touchscreen flex, I disassembled the Kindle to inspect the touchscreen digitizer and nothing looks obviously wrong. The flex cable has a chip soldered on board as well as some other passives and a couple of sot23 packages. I tried putting some pressure on those just to see if the problem was solder joints, but nothing.I kiiinda got it working for a fraction of a second making a lot of pressure on one section of the digitizer, with the Kindle assembled, but I can't replicate that.I tried putting it in a dry, cold environment. No change. Before that, I tried heating the digitizer a bit with a hair blower, nothing either.A new digitizer is $17, and perhaps I could buy one.

author: tautech
author_rank: Super Contributor
timestamp: February 22, 2015, 12:24:09 pm
content: If when you pushed firmly you were not making contact with leads or pads of any components I'd suspect a failed solder joint.Very carefull magnified inspection might find it, especially if it has any current to speak of through it.Look for a grey smudge or crack.I had a SMD & TH PCB some years ago that drove me mad trying to find a cracked joint that I knew was there. Flexing the PCB can produce a click-clack signifying a cracked joint.In that case a total resolder fixed it.But it seems you already have a possible area to concentrate on....good luck.

author: ivan747
author_rank: Super Contributor
timestamp: February 22, 2015, 12:51:45 pm
content: We'll see... I'll try a visual inspection of the flex, and a visual inspection of everything that leads to the touchscreen connector on the motherboard.A brute force aproach would be reflowing these areas with hot air, right? The problem is, I don't have a hot air rework station, and for what is worth, I can buy the digitizer for this and an upper screen for a Nintendo DS I also want to fix. I can also try with a soldering iron, of course.

author: amyk
author_rank: Super Contributor
timestamp: February 22, 2015, 04:02:58 pm
content: Could be the bonding of the flex to the digitiser glass ITO.

author: ivan747
author_rank: Super Contributor
timestamp: February 27, 2015, 08:00:03 pm
content: Quote from: amyk on February 22, 2015, 04:02:58 pmIs there a fix for that?I'd really appreciate a clean room (as in dust-free) when working with this sort of stuff

author: amyk
author_rank: Super Contributor
timestamp: February 28, 2015, 03:55:35 pm
content: I think they're usually bonded with a hot-bar type of process, so theoretically you could rebond it/use ACF, but that's not an easy fix. You could disassemble enough to get to the connection and then press on it to see if that is the problem.

author: ivan747
author_rank: Super Contributor
timestamp: February 28, 2015, 06:05:45 pm
content: Sounds like it. I'll give it a try.