The Samsung Galaxy S4, model i9505, features a 13-megapixel rear camera, and a 5-inch 1080p display.

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Motherboard swap on s4

Hey, I just recently wanted to bring life back to my s4 phone. I swapped motherboards from a mobile with broken screen to one that has been water damaged but with a perfect screen. Everything about the phone works now except im not able to call anyone. Internet/wifi works fine but im not able to make a call. I have contacted many different phone providers to check if the imei is locked but it is not. Can someone help me?

Answered! View the answer I have this problem too

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When you try to make a phone call, what happens specifically? Do you get an error message perhaps? Did you insert your carrier's SIM card in the phone before or after turning it on? Is the SIM card activated?


I can send a text messange only if i switch back and forth from airplane mode. I do not get any sim card messages indicating that the phone is locked. The SIM card i activated and works with other phones i have tested. When i try to make a phone call i lose all signal and then it says that signal is unavailable.


Okay if this sim card uses 4G it will connect to 4G for data if the phone is set to acquire 4G network.

Once someone calls you or you call someone it will switch the network handoff to 3G / H+ then the calling incoming or outgoing starts.

Try playing with the network settings in terms of LTE / 3G / 4G. Try 3G and 2G mode (It's usually the second setting for the option). The first setting is auto switching from all modes using best preferred. You can set it to exclude 4G.

See what works and what doesn't.


Thank you so much for fast answer! I tried checking the antenna cables and they seem to be fine. Whenever i turn on and off airplane mode im able to send a sms. But the signal is lost when trying to make a call. Something must be causing this bad network connection, but im not able to figure it out. I tried swapping the back panels too without any luck.


It's an antenna contact issue but I'm not sure exactly sure which antenna connection is at fault here. The model number of each label behind the screen is important. I think it's best you post pictures here of the back housing with the model numbers on it and the charging port and the model number printed on the back of the screen frame itself (Usually just says i9505 or something like that).

Anyway there is some good information here on troubleshooting antenna contact issues:

I advise to avoid during board level repair stuff only as a last resort.


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You sure you did not forget to plug both sides of the blue antenna cable for antenna signal? One end of the plug goes to the charger port and the other end of the plug plugs to the bottom right area of the motherboard where the antenna connector is.

Also the back cover housing also has some antenna contact points. They will not match if it does not match the board number. Look at the back cover and check the model number on the top right of the back cover. The bottom loudspeaker which clips on with the back cover housing also has a model number as well because there is also another antenna connection done there.

The most important question is what is the model number for each phone? The model number is printed on a label sticked to the battery compartment. E.g GT-i9505.

If it says no sim card, check in the phone settings about phone if the baseband and IMEI is displayed. If yes then the most likely sim card reader is probably faulty.

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