In iPhone 4s FL4_RF burnt
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In iphone 4s FL4_RF (backside of wifi chip) gone short.If I remove it what affects or bypass will works?
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I'm not sure what you mean by "burnt" do you see black marks/visible damage, water damage oxidation?
If no---then in my experience no WiFi in a 4S is always the WiFi chip itself needs to be replaced.
If yes---then in my experience it is the WiFi coil that is short due to water damage.
I, too, used to take off this filter and I know there are several solutions out there that recommend taking of the filter to restore WiFi---this is generally helpful only because the heat of that operation will sometimes "reflow" the WiFi chip. Of course it is not an actual reflow, but that chip does like to get warmed up if it is acting up.
If you've tried 'reflowing' the chip, then you'll have to have it replaced to get your WiFi back.
jessa
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Actually my problem is black screen and vibrating while in charging.even I restored my phone successfully but no display backlight.you know apple designed for some safety for logic board to prevent more damage by any power problems and parts damage or short and if any connector not properly adjust.In the case when I phone get some hardware issues itself stop the some functions by auto power cut and this the black screen is part of this operation.Actually iphone alert us that something wrong with your hardware.
Oh heavens Jay, you are barking up the wrong tree! Your troubleshooting for a no backlight problem looks like this:
1.) Try a new display.
2.) Confirm that you have power (which you've done by connecting to iTunes)
3.) Find the visible board damage----almost always it will be the backlight filters near the LCD connector, or the LCD connector itself. Repair this area.
4.) If still not solved, consider backlight coil or diode
5.) If still not solved and you've confirmed the entire backlight circuit is functional (extremely rare--I've only seen this once in hundreds of phones) consider that the phone may have a chip level defect that is preventing the phone from exiting DFU mode which does have a black screen.
(cont) There is no "you know Apple designed for some logic board safety to turn off the backlight because of some short" Nah. That's kooky talk.
The way a short works is that current is able to find a 'short' path and doesn't have to travel through all the resistance of the circuitry of the phone---that's why the screen doesn't power on if there is a full short. Also, the PHONE doesn't power on---you won't be able to have the phone powered on and able to communicate with iTunes if you have a short in the phone like you are trying to troubleshoot.
This is a simple display problem.
jessa
my display is black,vibrating while charge.As I told you in this bad situation I restored my phone successfully by itunes.I checked my other phone's working display with this phone but same black no backlught.How can I find any short?
If I bypass L18_RF,L19_RF,L20_RF will it works? and FL4(near display connector) missing and also fl4 line broaken ,where this line going? I can't find please help!
5 Comments
How do you know that it is short?
by jessabethany
You know J6_RF is connecting with J5_RF by cable and J5_RF is connected with J7_RF front side of logic board.I found and all start from J7_RF.
by Jay
can you be a little more specific with how you checked J6_RF? You know that the center gold dot is supposed to have continuity with the pad closest to the filter right? Are you saying that the gold dot also has continuity with the other pads?
by jessabethany
Oh,Jessabethany please be little sure J6_RF is a coxial connector socket and it is easy to check by meter,if meter sounds beep then something wrong.
by Jay
You have to be more specific---exactly what two parts of the socket are you testing for continuity? If it is center gold pin and the pad leading to the filter then that IS supposed to beep. If it is the circular edge of the socket to the three other pads then that IS supposed to beep. If it is the center gold pin to the circular edge then that is NOT supposed to beep.
It might help you to compare to a known good phone. I doubt you have an antenna problem at all.
by jessabethany