No signal after motherboard replacement - Samsung Galaxy S7 Questions and Answers

Hi. I have a g935fd with a dead board. I bought an g935o with a broken lcd and took the board, stuck it into the 935fd and all went well except Im not getting a signal.
From what I have read, the 935o board is incompatible with the charging IC and antenna of the g935fd, hence the no signal issue.
Is there no way around this and is this really just a hardware incompatibility issue?
I took out the charging IC from the 935o easily since the screen was already broken. The problem is i cant easily swap it out since I risk ruining the good LCD.
Any chance to trick the parts into working together?

Related

Rear speaker busted

I came to sell my Fuze, and the new owner returned the phone because apparently the rear speaker (ringtones, music, hands-free) isn't working. I did a hard reset, flashed a new ROM, reflashed HardSPL, and nothing. So I changed the internal speaker, and nothing. I tested both the old and new speakers, and i did get a resistance across them so they aint blown. Unfortunately, I just ran out of warranty 3 weeks ago, and i don't want to pay $100s from HTC's warranty service.
Has anyone had this problem before? I know the source of the problem might be in the logic board (looked at leaked service manual). Does anybody know a specific way to further test the source of the problem, and maybe direct me in the path of purchasing the parts for it?
Thanks a lot
I had a similar problem and the HTC service centre had to change the speaker and the mother board ( luckily it was still under warranty)
I had the same problem. Changed the speaker but didn't work. A friend of mine disassembled the phone, couldn't fix it, when he assembled it, it worked. His guess was a bad connection in the electrical circuit. There is a metal plate below the speaker with multiple circuits. He said the problem was there. The other option is busted amplifier, which means either a new motherboard or a new phone. My friend had an idea about fixing the electrical circuit before the phone magically worked. If you wish I can ask him what he had in mind as I'm no good at disassembling phones
Yeah, that'd be awesome if you could get some info. Otherwise, the phone is worthless :\
You're talking about the speaker that's glued into the back housing, right? I took apart my phone to replace the LCD and ended up mangling the connector for that speaker. The wires broke and I ran over it with my office chair. No matter what I did I couldn't get it to re-seat properly. It would plug in, but still wouldn't work. I finally just soldered the wires directly to the two tiny round contacts just in front of the connector and it worked. I don't know of a good way off the top of my head to test the output, but if you have a connection problem, that's one way to fix it.

Replaced Digitizer, now No Internet Connection in status bar

Like the title says, I replaced the digitizer, but now my phone either isn't recognizing my SIM card, or somehow the antenna isn't working. I can connect to my home wifi network, I have full audio, full capacitive buttons and vibration....but signal bar just shows empty (i'm using CM10).
I've put my SIM into my other phone, everything works fine. I've checked all of the connectors on the motherboard, everything is connected and nothing is loose or pinched anywhere. Can someone give me a layout of which connections control what?
thanks.
Remember that there's actually two different antennas. My suggestion would be to recheck each connection and make sure there's a solid click when you connect it
Sent from my LG-P999 using xda premium
rtotheichie said:
Remember that there's actually two different antennas. My suggestion would be to recheck each connection and make sure there's a solid click when you connect it
Sent from my LG-P999 using xda premium
Click to expand...
Click to collapse
the top connector came off the wire when I snapped it from the motherboard. I crimped the wire back in place but maybe I sould solder.
Crimp should work if the center pin is still making contact with the wire. Soldering shouldn't hurt anything that I can think of
Sent from my LG-P999 using xda app-developers app
guitarist5122 said:
Crimp should work if the center pin is still making contact with the wire. Soldering shouldn't hurt anything that I can think of
Sent from my LG-P999 using xda app-developers app
Click to expand...
Click to collapse
Update, I've purchased a replacement micro-coax cable, that fits correctly, but still have no signal coming to my phone for whatever reason. Any ideas, maybe getting a crappy g2x for parts and using it's cable?
stevew84 said:
Update, I've purchased a replacement micro-coax cable, that fits correctly, but still have no signal coming to my phone for whatever reason. Any ideas, maybe getting a crappy g2x for parts and using it's cable?
Click to expand...
Click to collapse
Where did you get the cable from?
Did you test the continuity of the cable's wire?
Core Memory said:
Where did you get the cable from?
Did you test the continuity of the cable's wire?
Click to expand...
Click to collapse
This is what I ordered:
http://www.digikey.com/product-search/en?x=12&y=15&lang=en&site=us&KeyWords=A36224-ND
stevew84 said:
This is what I ordered:
http://www.digikey.com/product-search/en?x=12&y=15&lang=en&site=us&KeyWords=A36224-ND
Click to expand...
Click to collapse
That should work. Are all the other internal connectors fully seated?
Core Memory said:
That should work. Are all the other internal connectors fully seated?
Click to expand...
Click to collapse
Yup, not too sure what's happening. I literally did NOTHING else to the phone except accidentally rip off the connection on the lower end of the phone. I still get Wifi, so I know nothing internally is broken. I need to call tmo on the off chance this phone got locked due to previous owner payment or reported lost or stolen. It was an LG branded, g2x, though, which doesn't get sold throught tmo.
stevew84 said:
Yup, not too sure what's happening. I literally did NOTHING else to the phone except accidentally rip off the connection on the lower end of the phone. I still get Wifi, so I know nothing internally is broken. I need to call tmo on the off chance this phone got locked due to previous owner payment or reported lost or stolen. It was an LG branded, g2x, though, which doesn't get sold throught tmo.
Click to expand...
Click to collapse
The LG brand could mean that the digitizer was previously replaced. It sounds like a very peculiar situation you are in. Replacement parts idea is probably best if you have looked over everything very carefully and can't visually find anything wrong. Did you use a hair dryer or other heat source to get the digitizer off? Perhaps the radio portion received to much heat and fried. That the only thing I can think of.
guitarist5122 said:
The LG brand could mean that the digitizer was previously replaced. It sounds like a very peculiar situation you are in. Replacement parts idea is probably best if you have looked over everything very carefully and can't visually find anything wrong. Did you use a hair dryer or other heat source to get the digitizer off? Perhaps the radio portion received to much heat and fried. That the only thing I can think of.
Click to expand...
Click to collapse
When I first did the repair, I ripped the ribbon from mother board to digitizer, not realizing it was there in the first place. The screen separated from the digitizer pretty easily, no heat required.
The new piece I ordered had the digitizer and outside bezel all attached as one piece, which would normally be two pieces. While constructing everything, I forgot that little rubber/plastic piece that fits near the front facing camera, so I detached the mother board connections, then went down to the antenna area and disconnected the micro coax and the connector slipped off the cable altogether. I put the exposed wire back into the connector, restarted the phone, and there has been no signal ever sense.
The last thing I'm going to try is getting an OEM micro coax from either a P990 or P999. I feel kind of stupid for worrying about this, since it's an old phone with limited development at the moment, plus I have another phone already. But since I bought an entirely new shell, I want to fix this damn thing and probably just sell it.
stevew84 said:
Yup, not too sure what's happening. I literally did NOTHING else to the phone except accidentally rip off the connection on the lower end of the phone. I still get Wifi, so I know nothing internally is broken. I need to call tmo on the off chance this phone got locked due to previous owner payment or reported lost or stolen. It was an LG branded, g2x, though, which doesn't get sold throught tmo.
Click to expand...
Click to collapse
Canadian G2X/P999 are branded LG and are known as Optimus 2X even though they are not the P990 Optimus 2X which is/was also sold in Canada, each model sold by different service providers operating on different cell radio bands. At a point, T-Mobile was supplying LG branded G2X/P999 phones as replacements. You probably have one of those or, if you bought it from someone in Canada or who was in Canada that would also explain why yours is branded LG.
If you shorted the antenna cable's internal wire to its shield that would short-circuit the cell radio's output which may have damaged the hardware if the phone transmitted while there was a short-circuit.
Core Memory said:
Canadian G2X/P999 are branded LG and are known as Optimus 2X even though they are not the P990 Optimus 2X which is/was also sold in Canada, each model sold by different service providers operating on different cell radio bands. At a point, T-Mobile was supplying LG branded G2X/P999 phones as replacements. You probably have one of those or, if you bought it from someone in Canada or who was in Canada that would also explain why yours is branded LG.
If you shorted the antenna cable's internal wire to its shield that would short-circuit the cell radio's output which may have damaged the hardware if the phone transmitted while there was a short-circuit.
Click to expand...
Click to collapse
I think what I need to do, if i wanted to keep this phone, is the buy a crappy g2x and use it's internal motherboard with antenna and coax cable.
Does anyone know what the board is called at the bottom of the phone, near the charging port? It's where one end of the micro coax cable connects. The other end is near the middle of the phone, on the main mother board.
I'm wondering since the board at the bottom had the problem, if I were to replace that.
Here's the repair manual:
http://www.scribd.com/doc/84937521/70/EXPLODED-VIEW
There is a way to test the cell phone radio to determine if it works but it involves installing some Qualcomm software, QPST and QXDM, which are professional tools for monitoring, testing and modifying the phone's Qualcomm cell radio characteristics. My post about how to fix the P999 IMEI has the download links and instructions for setting QPST up: http://forum.xda-developers.com/showthread.php?t=1942417 I'll find the QXDM link and installation instructions and post it in this thread too.
Here's QXDM 03.11.36 http://www.mediafire.com/?tmzmngemgmm
Install them both as Administrator.
Core Memory said:
There is a way to test the cell phone radio to determine if it works but it involves installing some Qualcomm software, QPST and QXDM, which are professional tools for monitoring, testing and modifying the phone's Qualcomm cell radio characteristics. My post about how to fix the P999 IMEI has the download links and instructions for setting QPST up: http://forum.xda-developers.com/showthread.php?t=1942417 I'll find the QXDM link and installation instructions and post it in this thread too.
Here's QXDM 03.11.36 http://www.mediafire.com/?tmzmngemgmm
Install them both as Administrator.
Click to expand...
Click to collapse
Awesome, I'll give it a shot when I get home, see what happens.
stevew84 said:
Awesome, I'll give it a shot when I get home, see what happens.
Click to expand...
Click to collapse
I've written up a procedure to determine if a phone's cell radio is working.
http://forum.xda-developers.com/showpost.php?p=33779273&postcount=1
Finally fixed the damn thing, adjusted the length on either side of the mico coax, the cable isn't being pinched anymore so it works fine. I have a slight problem, though, I have some bright light bleeding from the middle left, and top right of the screen. Maybe because the LED isn't seated flush against the digitizer? Is that what would cause this?
It's minimal, and I don't want to take it apart, but still curious.
Around the screen edge there should be attached to the digitizer a thin foam gasket. If it is missing a piece of the thin foam or if it somehow got disturbed or is not there it most likely is where the bleed is comming from.
Eddie
Sent from my AT100 using xda premium

Which component did I destroy? (Almost all lte/hspa+/edge packets are lost.)

Hi,
I replaced the screen of my brother's Nexus 5 and even so the display works perfectly we seem to have destroyed a component.
I managed to connect the device to lte/3g/2g networks (see photo in the attachment) and sometimes a few packets are even successfully transmitted but that's an exception. Usually it is not even possible to load a website within a reasonable amount of time..
Wifi works.
Stock and cm13-caf firmware show the same behavior.
Like shown in the photo the phone is successfully connected to a 4g/lte network.
Phone calls on a 2g-network work.
Any ideas to which component we have to replace? Or any hints on what could give more information about the actual issue?
Thanks in advance!
Best Regards
Michael
Does the original screen still work? If it does, you could try moving everything back to see if that makes a difference.
When you replaced the screen, did you use a where the LCD/frame/glass were pre-assembled?
Thanks for your response.
I had two replacement displays and noticed the same issues with both of them.
(I bought a cheap one first from ebay which had multiple touch screen issues and only after that bought a way more expensive original replacement unit.)
Hmm, hopefully, it is not a motherboard issue. I would suggest trying the old screen is possible.
Another part that may affect signal would be the USB flex port cable. The other pieces that attach to the motherboard are the camera, headphone jack, USB charging/data cable, and battery.
We completely destroyed the old display unit after removing all other components except for the battery. This made it easier to bend it and remove the battery without damaging its enclosing.
I'm afraid it might be the mainboard but was hoping for a cheaper solution . The usb board is still a possibility since it routes a quite a few signals between components.... Are there some schematics of the device available online?
Haven't seen any schematics.
I guess you didn't use a hair dryer to warm the adhesive before using a spudger to remove the battery.
Examine the USB flex cable to see if there are any breaks.
If you get a phone with a smashed screen and working internals, you should be able to get the phone working.
I wasn't sure if heating up the battery is a good idea and since the old screen has already been damaged I really didn't care if it's even more so...
Heating the battery is fine as long as you keep moving the hair dryer around. The battery just needs to get warm, not hot. Also, you would heat it from the front of the phone, not the back.
I bought a Nexus 5 with a damaged display unit online and used its mainboard and antenna cables to fix my unit. Everything works again. Seems to have been something on the mainboard but I have no idea which component exactly.
Thanks for updating the thread with your solution.

Wifi, Bluetooth and mobile hotspot are NOT WORKING ! G930F

I have a problem with my s7 G930F, wifi and moble hotspot are not working at all, when i turn on wifi or hotspot it just showing turning on ..
and when i turn on bluetooth it works for 5 seconds and then keeps switching off and on after every 5 seconds
i tried to wipe cache, factory reset, return to stock rom, install custom roms, install latest modem and bootloader but that did not fix the problem.
please help !!!
Does your gps works ?
NeoDJW said:
Does your gps works ?
Click to expand...
Click to collapse
Yes it's.
NeoDJW said:
Does your gps works ?
Click to expand...
Click to collapse
Yes it works.
Check water sticker on botton of sim slot
I had the same issue with a board i fitted to G930F bluetooth wasnt working nor wifi for no apparent reason i went through absolute everything firmware wise and system wise and couldnt figure out what the problem was i then removed everything once again looking for a loose connection it turns out the board i fitted in the top right hand corner there is a silver chip that controls wifi and bluetooth under the antenna there was a small black spot i noticed once carefully cleaned up i found the culprit there are 2 tiny fuses that blew conecting to the wifi chip this chip must also control bluetooth and NFC as that no longer works also.
Martty
Do you find a solution
daliyoos said:
Martty
Do you find a solution
Click to expand...
Click to collapse
I did find the solution unfortunately it requires the wifi ic chip to be replaced along with the fuses accompanied to the chip on the logic board but that means micro soldering the new chip on the other solution is change the board out when you take the antenna at the top off at the top right is the silver chip look at the circuitry and you should find a black burnt out spot also check the aerial for plastic burn where the chip sits
Thats the only solution available that ive found, not even the factory binary found the issue with the hardware though
That one chip though controls the wifi/bluetooth/android hostspot/NFC funnily enough though even though its blown visually the wifi toggles on still and will every now and then pick a network up for a second, the bluetooth toggles on but will not find any other device and other devices cannot find it either, the android hotspot turns on and broadcasts a signal but when trying to connect to it it will not connect, the NFC toggle is also set to on with the writing and toggle greyed out and NFC apps asking to turn on the chip but it cannot be toggled these are symptoms of the error,
If you would like to inspect your device,
If you dont know what your doing order a new backing i can successfully remove them without cracking them with a hair dryer, screen puller the cheap ****ty ring ones, and a guitar pick,
To start heat the backing of the phone up with hair dryer until its warm/hot next step is my secret trick to pop the watertight seal take the sim tray out and no **** blow into it youll hear the seal break get the ring puller pull it up enough to get the guitar pick in and just slide it all the way round,
Once the backs off theres 3 screws at top on antenna your gonna wanna use a phillips #00 for them once the screws are out get a pair of tweezers and slide them into the slot on the left side of the antenna where the vibrator is and pull up it will probably go flying if you use to much force but it wont break, the circuit and wifi module are now exposed on the top right diagnose the board for burnt spots if there is there, take the NFC chip off below the antenna and then the speaker to expose the charging port check the bottom right hand corner for circuitry burning also.
Matty1993 said:
I did find the solution unfortunately it requires the wifi ic chip to be replaced .
Click to expand...
Click to collapse
Hi, I have same problem for long, I tried all software options: factory reset, network reset, hard reset, wipe, firmware upgrade, downgrade,,
I can use NFC without problem but WiFI and Bluetooth are greyed out or stucking on turn on without finding anything.
Could you confirm what is the right IC for it ? I found two different IC number one on Ebay another on Part4reparirs , not sure which one is legit as both claim to be G930 wifi-IC (can't add link as I am new user)
also I would be interested to know where to buy fuse for it
I really miss my phone for few month using spare xiaomi now
aminkian said:
Hi, I have same problem for long, I tried all software options: factory reset, network reset, hard reset, wipe, firmware upgrade, downgrade,,
I can use NFC without problem but WiFI and Bluetooth are greyed out or stucking on turn on without finding anything.
Could you confirm what is the right IC for it ? I found two different IC number one on Ebay another on Part4reparirs , not sure which one is legit as both claim to be G930 wifi-IC (can't add link as I am new user)
also I would be interested to know where to buy fuse for it
I really miss my phone for few month using spare xiaomi now
Click to expand...
Click to collapse
Hey mate im a phone technician,
Ive got a few boards qnd broken S7 laying around ill pull one down and take a picture and label it and what not & will post it here for you,
The ic chip isn't actually a fuse its an actual chip which controls the wifi and bluetooth functions of the phone NFC is locted on 2 different part of the board aswell as wireless charging coil etc, so if that stuffed best of getting a new board, but however there is a small thermistor (ThermalTransistor) just before the wifi bluetooth ic hopefully for you its blown that and stopped current before getting to the wifi ic, i will also label this in the diagram
Hopefully in your case its the thermistor youll know anyway if it is will be blown with black or white residue everywhere and your antenna may be partially burnt out in that case, you will also need to check the daughter board for black or white burn residues also in the bottom right hand corner ill take a picture and label again also,
If i cant get the pics up straight away for you its because xda app is being a pain in the ass still and wont let me upload being playing up for a week now
Matty1993 said:
Hey mate im a phone technician,
Click to expand...
Click to collapse
Thanks for reply,, based on your explanation still other thing like antenna fuse thermistor could be damaged and ordering them one by one + shipping is not good idea.. I may better find cheap broken LCD S7 and ask technician to swap the board for me.
still looking forward to the pics... my Insta Gram acc is [at]kian.moments :fingers-crossed:

Nexus 5 in a (kitchen) oven, a good candidate for eMMC replacement?

Greetings everyone,
I would like to explain my situation then ask you -especially to those with soldering irons - whether my now dead Nexus would make a good candidate for a project like KApetz2's eMMC change in https://forum.xda-developers.com/showpost.php?p=66237485&postcount=12 (simply is it worth bothering?)
History:
My good old Nexus 5 (32GB) started losing its microphone capabilities first, then I have applied some pressure on top of 40-pin connector and solve but in time I guess I have broken the connector. Anyway, then that I have a working phone with no touch or screen capabilities, I decided to try to melt solder in my old kitchen oven (30mins in preheated 300 degrees Celsius.). Then, obviously, my phone died completely.
Question:
1) So do you think I have burnt the eMMC? Or should I expect some other components to be fried?
2) Do you think is it worth trying to save my phone with a project like I have mentioned above.? I am a total noob with BGA soldering-desoldering.
Thanks for your time,
If you want to repair this connector you have to use an hot air soldering iron, sad to say but your phone is dead :/ i tried the same method and broke a 32gb mainboard (the phone showed funny colors on the screen and it wasn'tthe cable or screen)
got another board by a friend, this time with the hot air.
it worked fine
It could be the eMMC, you can try, but the chances are minimal, there are a lot other components on that mainboard. If you want to spend money, try it, but i would say, it's not worth it

Categories

Resources