[Q] Galaxy S4 Connectors Under Back Cover

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-beluga-

Senior Member
Nov 11, 2006
98
8
Hi -

Does anyone know the specifications of the 4 connectors under the back cover?

I think the ones to the left of the flash are for wireless charging.
What polarity are these?
Can you fry the phone when connecting with wrong polarity or is it protected?
What are the connectors to the right of the flash for?

Thanks!
 

springarchie

New member
Aug 4, 2007
2
0
Two of the four connectors

The Telstra Samsung Galaxy S4 4G has two external antenna ports L1 and R1.
When connecting your Galaxy S4 to an external antenna it's important to only use the R1 port.
The L1 Port is for LTE MIMO operation only.
 

randomtask16

Senior Member
Apr 5, 2007
127
4
Bringing this back up to add some info.
I had been researching fixes for the diminished signal when using the Zerolemon 7500mAh battery. Figured out that my laptop TV tuner card antenna uses the same connector as the L1 port on the GS4 and tried it out. I got about 8-10dbm signal increase across all bands. The test was done with the phone stationary inside a concrete walled large warehouse with moderate signal in south DFW.

I noticed that GSM had the best signal, then WCDMA then LTE the lowest. This may be due to connecting to difft towers, or other factors. But I think the concrete walls vs frequencies have an effect on things.
GSM
Before: -83
After: -69

WCDMA
Before: -85
After: -73

LTE
Before: -101
After: -89

Unfortunately I have no idea what type of connector it is, nor where the antenna came from.
Since it has a detachable retractable mast I tested it with and without. It actually had the same signal with it off, so I
would think you'd only need the wire itself to gain signal. My next step will be aquiring another connector, then create a modified version
using ribbon cables that can stick to the inside of the battery door.
 
Jan 14, 2014
22
2
I plugged a copper wire into the R1 port in the back of the phone and I guess I really messed something up internally b/c now when I don't have a piece of metal stuck in the port I get little to no signal anywhere. Also, since this happened I can no long make calls or texts on LTE b/c my phone's radio will not switch over to make the calls or texts. I can receive them though. Any fixes? I'm assuming a messed up a copper connection under the port by jamming crap in there. I'm going to remove the back of the phone and see if I can see any damage to the circuit board. I will report back with my findings.

EDIT: THIS WAS DONE ON THE SPRINT TRIBAND MODEL. (L720T)
 

Robcr

Senior Member
May 2, 2013
62
2
I plugged a copper wire into the R1 port in the back of the phone and I guess I really messed something up internally b/c now when I don't have a piece of metal stuck in the port I get little to no signal anywhere. Also, since this happened I can no long make calls or texts on LTE b/c my phone's radio will not switch over to make the calls or texts. I can receive them though. Any fixes? I'm assuming a messed up a copper connection under the port by jamming crap in there. I'm going to remove the back of the phone and see if I can see any damage to the circuit board. I will report back with my findings.

EDIT: THIS WAS DONE ON THE SPRINT TRIBAND MODEL. (L720T)

Worrying as I've just ordered a mmcx to sma adapter to try something similar. As mmcx to rp-sma seem harder to gt hold of I would be bridgeing with a small piece of wire, but not directly into the samsungs xt aerial port.

The prior posts regarding this on a number of sites are contradictory
Some say that nothing disables any and that the electronics always seeks the highest signal from either internal or external

I saw at least one pot that said you have to manually select (somehow) the internal aerial after using the external

Some say teh external doesn't work and is only for testing purposes, which has apparently been refuted by samsung tech support.

UPDATE
read here
http://forum.xda-developers.com/galaxy-s2/general/external-antenna-socket-warning-t1273292/page8

+ google 'Samsung galaxy s4 how to change antennas' for a youtube vid using battery monitor utility
 
Last edited:

Ghozer

Member
Feb 15, 2009
5
1
I think he means these connectors (see attachment)

S4.jpg

the R1 and R2 antennae are to the right, and aligned vertical...

The others, are aligned horizontal, there's a larger to the right of the flash, and a smaller to the left....

wondering what these are for, is what brought me here....
 
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boryz

New member
Jan 20, 2018
2
0
exactly! i am wondering the same

I think he means these connectors (see attachment)

View attachment 3527464

the R1 and R2 antennae are to the right, and aligned vertical...

The others, are aligned horizontal, there's a larger to the right of the flash, and a smaller to the left....

wondering what these are for, is what brought me here....

wonder if there was ever an answer to this:confused:
 

audit13

Inactive Recognized Contributor
Jun 4, 2012
12,915
5,051
Toronto
The two smaller connectors on the left are contacts for a wireless charging pad.
 

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audit13

Inactive Recognized Contributor
Jun 4, 2012
12,915
5,051
Toronto
I have no idea what the other 2 connectors are for. At first I thought it was for NFC but that doesn't make sense since there are no corresponding connectors inside the back/battery cover.
 

ObnubiladO

Member
Feb 19, 2019
6
1
I have no idea what the other 2 connectors are for. At first I thought it was for NFC but that doesn't make sense since there are no corresponding connectors inside the back/battery cover.

There's a cutout in the back cover for an NFC antenna (it isn't there) that matches perfectly with those 2 pins, which makes me think that Samsung decided to include the NFC antenna in the battery instead after the phone's design stage was done.

I highlighted the area where the pins would have made contact with the back cover NFC antenna in this photo.

ZlBFgQY.jpg
 
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    I think he means these connectors (see attachment)

    S4.jpg

    the R1 and R2 antennae are to the right, and aligned vertical...

    The others, are aligned horizontal, there's a larger to the right of the flash, and a smaller to the left....

    wondering what these are for, is what brought me here....
    1
    The two smaller connectors on the left are contacts for a wireless charging pad.
    1
    I have no idea what the other 2 connectors are for. At first I thought it was for NFC but that doesn't make sense since there are no corresponding connectors inside the back/battery cover.

    There's a cutout in the back cover for an NFC antenna (it isn't there) that matches perfectly with those 2 pins, which makes me think that Samsung decided to include the NFC antenna in the battery instead after the phone's design stage was done.

    I highlighted the area where the pins would have made contact with the back cover NFC antenna in this photo.

    ZlBFgQY.jpg