Samsung Galaxy J7, also known as Samsung Galaxy J7 Duos with dual-SIM card slots. It was released 2015, June, with 5.5 inches plastic material body, and 720 x 1280 pixels display resolution. Android OS, v5.1. This phone has 13 MP Primary Camera and 5 MP Secondary Camera, and it has a removable Li-Ion 3000 mAh battery.

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Which part of the phone has to do with SIM functionality?

I dropped my phone in soup (I'm not looking for help with water damage, I already took care of it), but mobile data is not working and I'm not sure if it's the phone or the card. Can someone point me to the area of the phone that has to do with SIM function or should I just give up?

Edit: I got some images from the teardown video (they're better than any I could take). I do need to make it clear that I'm very new to this and that I simply don't have most of the equipment that your suggestions would require. When I say that I'm not sure if it's the phone, I mean that I'm not sure if the moisture may have caused parts to malfunction. I was already thinking about ordering a new logic board and replacing it myself, as I already took it apart a few days ago and there didn't look to be any signs of corrosion, but I could always be wrong. I'm currently acquiring a SIM card from a friend to test if it's the card or the phone. It's looking like it might be the phone though, I put the SIM card into an old phone and the phone did detect the card and registered that it was from a different carrier, so If someone could point out which part of the logic board would have to do with SIM functionality so that I could check for anything that looks out of the ordinary, that would be very helpful!

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Andrea Chen did you delete your question that explained what happened to your phone?

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Yes, I did, because the responses were not very helpful, mostly just people berating me for how irresponsible I am. As rational as they were, I ended up just going with the advice from IFixIt's water damage repair guide. It was much more helpful. And... I just realized, you were one of the people that commented on it weren't you? I'm sorry about that but all three of you were telling me stuff I'd already figured out online so I just followed the official guide instead.

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Deck the Halls
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Great question! Let me first answer by saying NO you should NEVER give up. ANYTHING and I do mean ANYTHING can be figured out with enough energy and time. So let's continue.

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It could be either one. Your phone or your sim card. The best way (in my own opinion) to test a sim card is to call your phones carrier using another phone so they can have you run tests. So if you use Verizon call them up, Straight Talk, Sprint, Etc, call them up. They can actually diagnose a lot better than you or I can. In addition you can make the call toll free and do not need to obtain an additional sim card.

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However they may just tell you it is the sim card because your device isn't registering the sim card. In which case as @avanteguarde stated your next step would be to acquire another sim card that you KNOW works. The issue with this is, its more work than making a phone call.

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First you will need to find a SIM card that works with your phone, and carrier. Then you need to have your carrier activate the new SIM card in order for it to work with data etc. Then after that if it doesn't work, you will either need to reactivate the old SIM (if you borrowed sim card) or think about replacing the phone / part.

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Now if it comes down to the phone needing repair we have three options. Junk the phone, Send the phone in for repair, or do it yourself and un-solder your SIM card reader and solder a good reader in it's place. Be warned the motherboard my just be faulty in that area, in which case replacing the reader does no good, you will need to replace the motherboard.

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The good news to that is, motherboards are much easier to replace then to start soldering and un-soldering things. There is no official motherboard replacement guide, however there is a tear-down guide that if you watch carefully, could use to identify your SIM Card reader and replace it as well as the motherboard. You can find that here.

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I don't have the equipment to solder something and would rather not burn myself trying to make due with a hot glue gun just because I'm a cheapo, but if memory serves, what I think was the sim card reader (I assume that's where you put the card in? ) was part of the logic board. It looks like it's leaning towards being a faulty phone (I'm borrowing a SIM card just to make sure), so could I just replace the entire board if it is?

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Yes exactly! If you don't feel comfortable soldering or just simply don't have the tools, then there is nothing wrong with just replacing your motherboard. Just use that tear down guide above and you can use the link below to browse for parts. Keep in mind I think the part is a bit pricey so feel free to take the info from the link and do some shopping around to find the best price!

http://www.ebay.com/itm/OEM-UNLOCKED-SAM...

In addition to answer your question, yes the part your SIM card plugs into is in fact the SIM Card Reader, which you can replace separate if you want to.

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Andrea, simply put, APN settings are changeable settings that are stored in your phone. Those APN settings control how your phone "communicates" with your carrier / cell towers and allows things like mobile data etc. Sometimes those settings can get messed up, if they do, small things like data or even picture messaging my not work. The crazy part is in some events, you can still make calls etc, but will not have data, or you may have data and no picture messaging. The best way to solve this is calling your carrier as they can walk you through the EXACT settings you should have for your phone. Its free and they will even walk you through how to get to the settings.

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Andrea, we can provide more specific instructions regarding the APN if you can tell us which phone company you are with.

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Andrea Chen the previous answers are spot on. Now there are things you can do but they are on a board level. You could always get a multimeter and check the caps that are listed in the trouble shooting flowchart. If you post some good images of your logic board, we can mark the components to measure and can let you make the determination if you want to repair or replace. Use this guide to add images to your question.

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I have no cameras that would work well for this application, hope the one I posted works

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If you can get a known working SIM card and try it in the phone, that should tell you if it is the SIM or not. Make sure the phone has the APNs properly configured. The APN tells the phone on how to get mobile data.

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I'm pretty much incompetent but still trying when it comes to technology and don't know how to configure the APNs so I'll ask you to elaborate on that if it's not too much trouble.

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Which phone carrier do you use, Andrea?

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MetroPCS. My friends seem adamant on getting me to just replace my phone though.

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Hi Andrea, try this video to set APNs.

https://www.youtube.com/watch?v=AZgjCqaJ...

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Andrea Chen will be eternally grateful.
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