After my AT&T Samsung Galaxy S4 screen cracked I figured that buying a new screen on eBay was the best course of action to take to fix the phone. While browsing for the best screen I came across a cheap listing of a Samsung Galaxy S4 already assembled screen (apparently the unit was DOA but the screen worked). Naively I thought buying this listing would be most convienent: all I had to do was switch out the internals and I would have a working phone and screen without having to take out the hairdryer.
It turns out, however, that I mistakenly bought the SGH-I720 model. There are several differences between the I720 model and the I1337 model. The external loud speaker from AT&T, for example, does not fit the I720 model. The digitizer touch component (located to the left of the battery) is constructed differently. The back casing (the plastic mold covering the internals) will not fit on the I720 model because of this digitzer component. Oh, and apparently I do not get any GSM service from my AT&T carrier.
The rest of the phone works perfectly though. Wifi, bluetooth, the camera -- etc. Everything else that was transfered over with the main motherboard works.
I suspect it's an antenna issue. Obviously, right? I do get some service though! I just have limited GSM connectivity. Is this because of a carrier lock? The key difference between the I720 and the I1337 is the bottom part of the phones (underneath the loud speaker). It appears that the I720 model has two antennas whereas my I1337 phone only has one. I'm assuming the I720 is capable of GSM connectivity (it says so on the product page) and therefore believe that the GSM antenna (on the right of the battery) should work. I also believe that it is properly working. Why else would I have signal (albeit weaker than I'd typically expect -- but that could be because I haven't fully constructed the phone and the case isn't on etc, etc.
So my question is: does anyone know how the carrier lock works? Does Sprint have it hardwired in the phone or is it purely software? If it is a software thing than I shouldn't have an issue -- I do, after all, have an AT&T phone in a Sprint body. Does anyone here with better technical expertise know why the bottom half of an I720 phone is simply incompatible with a motherboard from I1337? For testing purposes I connected the antenna from the motherboard in the I720 to the bottom half of the broken I1337 phone. I still get service but again -- limited connectivity and emergency calls only.
Any help? I'm thinking I should just cut my losses and buy a new screen and just manually replace the screen on the I1337 but I'm sitting on a working front end to a I720 and I really really want to make this work.
EDIT: I realize that it's L720 and not I720. Oops.
But here's an update: I moved back the motherboard from the L720 to the I1337 (where it came from originally). I just plugged in the screen from the L720 so that I could see what was going on (the I1337 screen is flat out broken). TURNS OUT that I don't get service period from the I1337 model! Which hopefully means that a) I'm not connecting something right or b) it's a really simple software issue that you guys know how to fix?
I did try calling 911 and I did hear a voice on the other side very briefly. I immediately hung up. So I have a feeling that my phone is connected to a network but isn't being properly recognized. Is there an emergency number that I could call to test my phone (that's obviously not 911)? I just want to hear a reocrded message or something that gives me a set of instructions...
You cannot use the L720 for any network other than Sprint in the USA. You have to call Sprint to unlock it internationally and then enter a gsm sim while out of the country and only then can you use it. There are several threads that explain all of this already. Just a suggestion but don't call 911 and hang up.
Sent from my Sprint Galaxy S4 using Tapatalk 2
Dude, I'm confused... You have an L720 logic board inside of an I337 body or is it the other way around?
Sorry for the confusion. I have the logicboard of an I1337 (AT&T) inside of the body of L720 (Sprint). The only Sprint components of the phone are the body, the LCD / digitizer, and the small electronic board found towards the bottom of the device (one end of the antenna is connected here . . . the other end on the logic board). See my attachment to get an idea of what I'm talking about when I say "bottom of the device."
Regarding using the L720 in the US with other networks: I understand that the L720 is locked to the Sprint network. However, I have an AT&T (I1337) logic board. Where does the lock come into play? If the lock is software based... it shouldn't be an issue. If the lock is hardware based but isolated on the logic board... it shouldn't be an issue.
same issue
Any luck resolving this issue?
Related
Background:
I was running the most up to date Paranoid Android rom, working great for weeks.
I went to the east coast (where my phone worked fine), and when I landed in Chicago, I turned off airplane mode and didn't have any data. I thought that was odd, so I tried a factory reset. No change. No big deal, I take another plane to Seattle. Then I only get Edge. The next morning I got 3G/4G for a few hours, then it was intermittent that day, but for the last 3 I haven't gotten any 3G/4G. That's where I am now, although I put on the 4.3 factory image and locked the device. This is what I have tried:
I'm on Straight Talk T-Mobile
1. My wife's T-Mobile post-paid sim card.
2. Cycling airplane, turning phone on and off
3. Flashing CM 10.1 RC3
4. *#*#INFO#*#* and messing with the settings, doing anything and everything I can think of. WCDMA Only, preferred, turning radio on and off, and trying to get to the radio band menu. The radio menu popped up just fine on CM10.1, but crashes on stock 4.3. When I select WCDMA Only, I get zero service at all.
5. Cleaning my sim card with rubbing alcohol
What I haven't tried:
1. Flashing a radio.
2. Taking it apart and inspecting the antenna connections.
Does anyone know if there are multiple antennas for the GSM/WCDMA radios? I looked on Ifixit and I don't see much info on the antenna. parts4repair.com shows only 1 antenna. The thing is, I get great signal on Edge, so if it's only one antenna, then I wouldn't expect such a good Edge signal. Also, the Edge/WCDMA signal processor is on the same piece of silicon, so I wouldn't imagine that would be a problem.
My phone has slipped from my lap a bunch of times and has been dropped on carpet quite a bit, never with any visible damage. I'm starting to think that it was damaged when dropped. I know there aren't great crumple zones on this phone.
Does anyone have any other thoughts, or ideas? I would like to try a few more things before I crack it open.
Thanks,
Ders
Update: I have since opened the case and disassbled the phone. I cleaned the contacts for all of the connections that I could find. I also see that the antenna cable attaches to the board that holds the micro USB port. Another plastic piece snaps in above that. This plastic piece has pressure contacts for a fractal antennna that is basically printed on this plastic piece. If I had to guess, the antenna may have been damaged due to flexing when the phone has been dropped. I ordered a new one on eBay and will see if that does the fix.
Another interesting thing that may disprove my theory. When I disconnect the fractal antenna, I still get an Edge signal. If it doesn't fix the problem I'm going to have to hook it up to an oscilloscope and see what kind of signals are being broadcast. That way I can see if it might be the signal processor chip on the motherboard.
Another update. I ended up replacing the USB board, antenna board and antenna cable. Works like a charm. Seems a little slower than my wife's Galaxy S3. But hey, it works now.
Sent from my Nexus 4 using Tapatalk
Default [Q] new mother board/ logic board
Have an sgh I337 att galaxy 4,
My issue and question, i have had this phone for a while it has seen a LOT of abuse, have replaced busted screen 2 times!
with that in mind latest issue and yes did factory reset camera shows nothing on screen and says a error, also wifi will not turn on at all slide to turn never connects goes to off position, ni assume due to many drops the board had said enuff, !
now my question if i buy a new logic board / mother board will i have issues connecting to my provider? AT&T, imei # and so forth, or will popping in my sim negate that issue?
no reply? meh
you can try to buy a new camera (for i9505) on ebay to fix it,
for the wifi sadly it sounds like a motherboard issue.
basically, if you buy a new mb its like buying a new phone, so make sure the emei is not blacklisted, other than that you will be fine
Hello guys
Just picked up a LG G2 (Verizon variant VS980 according to the branded back and thicker size), but the LCD is dark. I did notice right away that the LCD must have been replaced as it doesn't have any Verizon branding in the top right corner (as the retail version has). The phone is fully functional, turns on, boot sound, beeping when volume is pressed, able to receive calls, and responds to touch (like able to answer by blind swiping, pull down notification and feel responsiveness when top toggles are pressed) but all with dark screen. I can see the backlight is good (some slight leakage) but not a single pixels lights up.
The previous owner told me the screen needs to be replaced, but didn't mention why. I assume he replaced it (or paid someone) with a GSM (D802/D800) variant and something must be different/not compatible. I thought the only difference was the wireless charging and CDMA board. I am wandering if there are any "easy" ways of solving this without purchasing the correct part (like possible modifying or replacing the connectors, or maybe flashing something?) Is there any chance that one of the ports/connectors is broken (and not the LCD itself?) Are there aftermarket LCD screens for Verizon variant that don't have the Verizon branding (thinking maybe it's a correct part, but defective) or all VS980 models come branded? I am just surprised that the wrong screen "fitted" so well. I am sure this was probably mentioned somewhere, I couldn't find a post with anything after search. Thanks for any feedback/input you can provide.
You bought a phone someone else fixed themselves. If you can fix it, open it and see how he did the repair & redo the job.
If not, you'll have to get it replaced professionally. LG won't warranty replace the screen since its obvious its been opened...
coolmen777 said:
Hello guys
Just picked up a LG G2 (Verizon variant VS980 according to the branded back and thicker size), but the LCD is dark. I did notice right away that the LCD must have been replaced as it doesn't have any Verizon branding in the top right corner (as the retail version has). The phone is fully functional, turns on, boot sound, beeping when volume is pressed, able to receive calls, and responds to touch (like able to answer by blind swiping, pull down notification and feel responsiveness when top toggles are pressed) but all with dark screen. I can see the backlight is good (some slight leakage) but not a single pixels lights up.
The previous owner told me the screen needs to be replaced, but didn't mention why. I assume he replaced it (or paid someone) with a GSM (D802/D800) variant and something must be different/not compatible. I thought the only difference was the wireless charging and CDMA board. I am wandering if there are any "easy" ways of solving this without purchasing the correct part (like possible modifying or replacing the connectors, or maybe flashing something?) Is there any chance that one of the ports/connectors is broken (and not the LCD itself?) Are there aftermarket LCD screens for Verizon variant that don't have the Verizon branding (thinking maybe it's a correct part, but defective) or all VS980 models come branded? I am just surprised that the wrong screen "fitted" so well. I am sure this was probably mentioned somewhere, I couldn't find a post with anything after search. Thanks for any feedback/input you can provide.
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Click to collapse
Hello,
I had my phone water damaged and repaired, but now my WCDMA/LTE doesn't work and I have some suspicions they had a faulty repair on my phone. Here's a timeline of the events to understand why"
1. Bought I9505 (I live in europe, hence the european version). All worked fine, had HSDPA (no 4g when I bought it 2 years ago, since my carrier didn't support it yet).
2. Did a small dent in the phone's screen (cracked glass in the upper corner, near proximity sensor, tiny piece of glass missing [1mm], but touch screen worked fine)
3. Dropped it in water while on vacation. Quickly took out battery, bought a bag of rice and held it in rice for ~20h, hoping the water would be absorbed.
4. Next day I fully charged then turned on my phone, it was connected to 3g, I was receiving facebook notifications, my mother called me at one point and ringtone was working. The only problem: touch screen didn't respond at all so I couldn't answer or unlock my screen.
5. Took it to a local service, they changed my screen (and did a full reset on my phone that I wasn't asked permission for - that I didn't understand why, but I thought who knows, maybe they needed it for the screen change). However, I wasn't upset since I was more interested in getting my touch screen to work, and it did.
6. HERE's THE PROBLEM: yes, they fixed my touch screen, but now i have to use it only in "GSM only" network mode, since the others don't work: whenever I choose any of the other options ("WCDMA/GSM, WCDMA only, WCDMA/GSM/LTE"), I lose signal completely, and I get "Not registered on network" message when trying to call. I should mention that APN setting are correct and I tried the SIM in another phone and it worked. I also tried another SIM in my phone and it didn't work.
7. Somehow I thought it might've been the water damage and I was ok (although upset) with it. But I searched the internet for answers since I thought maybe I'd fix my phone due to a software/bad config problem. I used ODIN to flash different versions of official firmwares with no success.
8. HERE's WHY I'm SUSPICIOUS: I found some piece of information that said the LTE/WCDMA(data) module is embedded in the display, not in the motherboard. Upon further research, i found the USSD code *#2663# that tells me the display is from a SGH-I337 (S4 model used in the US). Thus, if the data module truly is embedded in the display, that would render my data service useless, since the US frequency is not the same with EU frequency.
What do you guys think ?
Is it truly the display's fault or did I get erroneous information regarding the WCDMA/LTE ?
Am I entitled to negotiate with them because they put an incompatible component on my phone for a partial refund or is this my phone's fault ?
Is there any way to force the frequency somehow so my phone works (rooting & modifying some modem files maybe) ?
I'm sorry if I had some presumtious/loaded questions, but it's all information that I had from the internet.
Thank you for your patience to read all of this.
Do us a favor please? Enter download mode (Volume -, Home, Power) and read off the model number listed there. Reason being that I suspect your phone was totally replaced, with an AT&T model.
Did that just now, the product name says GT-I9505. The IMEI is also the same as before (checked with the product packaging it came with when I bought it). Could they have any way to overwrite this stuff ? Because your knack is not unfounded - under the battery, the IMEI/SN sticker seems to have been peeled and re-glued since it's wrinkly and misaligned.
Worst part is they're authorized Samsung service partners, that's the reason I went to them and not another service. (I can find them on the samsung website, when looking for service locations)
It sounds like they simply moved your motherboard into an AT&T midframe. I'd take it back to them posthaste and have them fix it properly. Because LTE isn't working, and it was before they did their work, they are responsible.
Heya guys, to make a long story short, bought an S8 on ebay, Verizon G950U, and was told the camera didnt work and there was no IMEI etc...
Upon checking, the front camera has a torn connector. I fiddled around with the daughter board where the antenna connectors etc.. are, (breaking the speaker and its entire cover in the process) and sometimes I randomly get cellular back, but it doesnt stay for long. i'm not sure whats faulty, but I'm certain it has nothing to do with the mainboard. The latest time the connection popped back was when I tried moving the back cover back on, I guess something must have clicked. I already reinforced the wires and the surrounding connectors, but I cannot get cellular at will. Would replacing the board in it's entirety be a fool proof solution? Hoping for help on the matter.
EDIT: Not sure if it was coincedental, but Also during one of the times the cellular service returned, it was immediately when I plugged my headphones into the device.
Akumai said:
Heya guys, to make a long story short, bought an S8 on ebay, Verizon G950U, and was told the camera didnt work and there was no IMEI etc...
Upon checking, the front camera has a torn connector. I fiddled around with the daughter board where the antenna connectors etc.. are, (breaking the speaker and its entire cover in the process) and sometimes I randomly get cellular back, but it doesnt stay for long. i'm not sure whats faulty, but I'm certain it has nothing to do with the mainboard. The latest time the connection popped back was when I tried moving the back cover back on, I guess something must have clicked. I already reinforced the wires and the surrounding connectors, but I cannot get cellular at will. Would replacing the board in it's entirety be a fool proof solution? Hoping for help on the matter.
EDIT: Not sure if it was coincedental, but Also during one of the times the cellular service returned, it was immediately when I plugged my headphones into the device.
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Click to collapse
I had a note 5 that cellular issues because the quik plugs for the antennas wore out and it did a similar type thing Once I swapped mbs it worked like a dream