[fix] An easy way to solve the screen flicker with just a scotch tape

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wl030827

Member
Aug 7, 2012
17
26
Hey guys,I'm a nexus 7 user from China.
I have solved the screen flicker problem.
Just put a piece of scotch tape on the GND point of WIFI antenna.It does not influence the signal strength.

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tylerwatt12

tylerwatt12

Senior Member
Sep 30, 2010
526
171
Cleveland
www.tylerwatt12.com
Not gonna do that. By not connecting a ground you could run into some other serious problems later on. Excessive WiFi chip heat and possibly other issues

Sent from my Nexus 7 using xda app-developers app
 
W

wl030827

Member
Aug 7, 2012
17
26
tylerwatt12 said:
Not gonna do that. By not connecting a ground you could run into some other serious problems later on. Excessive WiFi chip heat and possibly other issues

Sent from my Nexus 7 using xda app-developers app
Click to expand...
Click to collapse

Won't be.I have studied the wifi antenna for several years.Wifi antenna has many types,some of them like omnidirectional antenna,it‘s RF line and GND is not connected.

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Remoteconcern

Senior Member
May 27, 2011
769
292
I've just done this. So far, wifi strength fine and there is definitely less flicker.

However, this its light outside and it's much easier to see the flicker when it's dark, so I'll let you know.

Thanks for the idea, and hopefully this works!

Sent from my Nexus 7 using XDA Premium HD app
 
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bkmaracas

Senior Member
Jul 10, 2012
134
54
Cardiff
Watching with interest, before I go through and attempt it.

may i ask what is your theory why this works? In simple terms! If I could sort the flickering I'd be v happy. Thanks

Sent from my Nexus 7
 
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Remoteconcern

Senior Member
May 27, 2011
769
292
Confirmed as working on my device. It completely eradicated the flicker too, which is awesome.

I also would love an explanation as to why it works!

Sent from my Nexus 7 using XDA Premium HD app
 
S

Solange82200

Senior Member
Mar 27, 2009
404
49
I cant really tell by the pic, is that just a piece of clear scotch tape taped over that metal part? Its not in between or anyway special right?
 
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ResistanceDown

Senior Member
Jan 29, 2011
81
13
Utah
Does anyone have any information on why this works and if there is any possibility of it messing up the tablet?

Sent from my Nexus 7 using Tapatalk 2
 
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ThePerson98

Member
Jan 31, 2010
49
7
Tulsa
So this makes me wonder if the common issues could perhaps be with the back of the device. I've seen people with screen warping issues caused by a warped back, and now there's a fix for flickering by modifying the back.

I'm sort of curious to see what switching the back of a flawless device with a device with flickering does.

Edit: I also remember someone saying awhile back that they pushed on a certain part of their device to make the flickering disappear, which makes me even more curious if it's something to do with the back..
Another edit: The device would not flicker when the back was completely removed. Obviously, without the antenna, the signal was very weak, but the flickering would disappear. As soon as I placed the back on again, the flickering returned.
 
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kenyee

Senior Member
Dec 11, 2008
74
4
ResistanceDown said:
Does anyone have any information on why this works and if there is any possibility of it messing up the tablet?
Click to expand...
Click to collapse

Only engineering theory is the antenna is moving the voltage for ground w/ the power surges when it uses full wifi power and this is affecting the ground level for the rest of the tablet including the backlight. By putting the tape there, you're preventing the wifi antenna from affecting ground level, though I don't understand why it doesn't affect wifi power (I'd think that by doing this, you're lowering the transmitting power of the wifi antenna).
Any other EE's confirm this might be what's happening?

Interesting workaround at least...it's basically a hardware version of the software workaround I theorized was possible if they could control the power transmission level of the wifi chip/antenna...
 
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ResistanceDown

Senior Member
Jan 29, 2011
81
13
Utah
I decided to go ahead and get a replacement... Call time 3:14 no joke. Super impressed with the service and the process.

Sent from my Nexus 7 using Tapatalk 2
 
e.mote

e.mote

Senior Member
Feb 16, 2011
2,160
887
Not sure what you're talking about in "disconnecting ground," but the ground plane is pretty important for PFA antenna design. (I'm assuming that's what the N7 has, as there still isn't a good photo of the ants themselves in any of the teardowns.)

BTW, funny, but I made that very same antenna in your pic, along with the PVC pipe cover. Didn't work too well as an omni. I soon ditched the DIY route when I found surplus WISP ants to be much more effective, and less hassle.

BTW, a good read for wifi design is "Antenna Design for Mobile Devices (Wiley 2011)."
 
T

ThePerson98

Member
Jan 31, 2010
49
7
Tulsa
ResistanceDown said:
I decided to go ahead and get a replacement... Call time 3:14 no joke. Super impressed with the service and the process.

Sent from my Nexus 7 using Tapatalk 2
Click to expand...
Click to collapse

I'm going ahead and doing the same. It does look like modifying the back cover will fix the flickering issues, but after reading a bit on how the ground effects antenna performance, I'm a bit wary about it in the long term. It'd be one thing to just tighten a screw, but to disconnect a wire with a function isn't okay to me.
 
e.mote

e.mote

Senior Member
Feb 16, 2011
2,160
887
I've pasted some pages out of the abovementioned wifi design text on the effects of ground plane on mobile antennas. It's probably too technical for many, but you can get the gist, which is that the ground plane is a "big deal" in antenna performance.
 

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  • 17
    W
    wl030827
    Hey guys,I'm a nexus 7 user from China.
    I have solved the screen flicker problem.
    Just put a piece of scotch tape on the GND point of WIFI antenna.It does not influence the signal strength.

    DSCF3566.JPG


    DSCF3568.JPG
    View
    3
    e.mote
    e.mote
    I've pasted some pages out of the abovementioned wifi design text on the effects of ground plane on mobile antennas. It's probably too technical for many, but you can get the gist, which is that the ground plane is a "big deal" in antenna performance.
    View
    3
    C
    Cynnthetic
    A lot of you here are describing the Tegra Prism auto contrast as "flickering" and its a different issue. If your screen gets brighter or darker slightly its a feature of Tegra 3. An ugly but normal one. There's apps to disable it if you search the forums. Flickering here is used to describe backlight failure due to interference. Totally different things. Tape won't stop Tegra.

    Sent from my Nexus 7 using xda app-developers app
    View
    2
    C
    chadteck
    I went to perform this mod and I noticed that there was some residue between the WiFi antenna contacts and the contacts were slightly offset from the pins. I cleaned the area and bent the pins a tad so they would contact the pads completely. I didn't place the tape because I wanted to try it after these changes.

    I have no perceivable flicker after doing this and my WiFi signal seems to be improved (no testing, just observation).

    I think the residue may have been partially conductive and causing a small short between the two pins. This would explain why some people experience this issue more than others and why for some, covering the pad with tape doesn't work (pin could still contact residue and create a weak connection).

    It would be interesting if some others would test this out and report results.
    View
    2
    A
    airmaxx23
    afrojoc said:
    I'd definitely this if I was more confident in opening my device
    Click to expand...
    Click to collapse

    Just slide your finger or thumb nail between the top edge and the back on one corner then slide it to the other top corner and the back will start popping right off, it's very simple.
    View

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