Diagnosing a Nexus 7
If you cannot directly probe what you are interested in, look for what it should be connected to and whether that gives you alternate means to access what you want.
The notch at the top is where the LVDS ribbon passes to the top side of the motherboard. Those eight vias near the top of the red ellipse are almost certainly where the ribbon connector’s LVDS traces jump to an internal layer, popping back out at the eight vias near the top of the purple ellipse along their way to the LVDS transmitter.
After confirming that the LVDS signals do indeed pop up at those vias, I continued my testing by checking continuity across the 10 pad 1608 packages around the LVDS chip. These are 27pF low pass filter chips with four channels apiece. canada goose women All of them measured up at 2.2 2.7, which means no shorts or opens there. The next thing I checked was shorts between the LVDS traces from the filter chips to ground. Looks like I have found my problem, except for one small detail. Can you guess what it is? The answer is in the picture. In any case, I ended up on a wild goose chase across the motherboard.
Now that I know for certain that there is a short on the ribbon cable, the next question is: where? There isn’t much that can go wrong in a flexible flat cable, especially on one where the signal traces never switch sides. It is a simple sandwich of one structural and two insulating polyimide layers with two copper layers for signals and power. Since there are no signal vias to short to other layers and no dents in the cable that could indicate a layer to layer short, the most likely source for my problem is under the wafer connector: a solder bridge between pins or pads.
Because my order was taking so long to arrive, I started the “where is my stuff” process on eBay and, after two weeks of chngsm asking me to wait one more week, he agreed to re send the order. I could have patiently waited for my replacement order to arrive, continuing to use my tablet as is. But what the heck? I have a hot air PCB rework wand now; I might as well use it.
I’m still using my 2013 N7, and luckily I’ve never had the sort of issues you describe here. Sure, the touchscreen is a bit slow, but nothing awful. I bought it late about two years ago now so that might explain some of this. After the Marshmallow update (hooray, an Android update arriving on time for the N7 2013 LTE!), it’s been entirely stable, and slightly quicker than before. By the way, I can’t remember ever needing more than two touch points. Repair, reuse, repurpose, resell. It survived numerous system updates unscathed until last December’s 6.0.1 update. It bricked it and required a factory reset. It always had the following minor issues though:1) Auto Rotation becomes locked unless an app forces it to change. Only a reboot fixes it.2) Sometimes the touch screen flakes out and stops registering touches. Power cycling (not rebooting, just putting to standby via the power button) fixes it, as does a reboot.3) It became unusably slow after the first 5.0 update. I wish I went back to 4.4.3(?) back then, but afterwards, games choked, apps stopped working well. But it still worked.4) The micro usb port is unstable. Have to play the “angle game” to get it to seat and charge properly. But it was one of the best tablets aside from those issues. Currently, its being used by my girlfriend as her first foray into the Android world.
I’m still using my 2013 N7, and luckily I’ve never had the sort of issues you describe here. Sure, the touchscreen is a bit slow, but nothing awful. I bought it late about two years ago now so that might explain some of this. After the Marshmallow update (hooray, an Android update arriving on time for the N7 2013 LTE!), it’s been entirely stable, and slightly quicker than before. By the way, I can’t remember ever needing more than two touch points. Also, remembering to keep a seldom used tablet charged is a hassle like no other and switching it off completely means a roughly 1 minute wait to turn on, by which time I’ve already picked up my phone instead.
I fully support repairing your N7 for a couple of reasons:
1: throwing away an otherwise fully functional piece of hardware is just dumb. Repair, reuse, repurpose, resell. The world has no need of more electronics waste.
My N7 issues aren’t over yet: the USB port on my N7 decided to die a few weeks after I sent this story in, so that’s one more thing on my growing laundry list of things to look into fixing. www.gooseonsale.top Now it only charges at a meager 280mA instead of the more reasonable former 860mA and I get no data connection to my PC. The next time a firmware upgrade goes wrong, it may be the end of the line.
for charging you should see about getting the docking station for it that charges by using the pogo pins on the side of the tablet
Lots of cheap tabs with 1GB of RAM, barely working digitizers, long outdated OS versions, no support and who knows how many other issues. I’m not going to buy another tablet with only 1GB of RAM on it: that may have been fine four years ago under Android 4.2 but with apps, APIs, runtimes and the core OS getting a little heavier each year, 1GB is barely enough to have one non trivial app open at a time on a 32bits ARM platform today. On x86 64, I’d even bump my minimum requirement to 3GB RAM based on how the ZenTab z580c’s 2GB RAM could barely handle two open apps at a time after I got done updating its bloatware.Google+