Reviving a wrecked motherboard. Schematics or capacitance/resistance measurement - Xiaomi Poco F1 Questions & Answers

Hello.
I'm looking for poco motherboard schematics or someone able to figure out what one smd compontent that I'm missing is:
View attachment 4866007
Story: a friend of mine smashed his screen and somehow, attempting to replace it, he tore off the mhf4/ipex coaxial cable connector on the motherboard, damaged the one on the bottom board with the charging port and broke the cable itself. I'm not sure how.
I already found and ordered the replacement parts but after cleaning the area on the motherboard where the old port used to be I found that he must have also blown off one of the 0201/0402 capacitors/resistors next to that antenna port.
The one that remained right next to it looks pretty much the same, so I could take that one off, measure it, and order a strip of those but I'm afraid to break something if it's actually a mismatch.
I searched a couple places for the schematics because in the past I had luck finding a pretty long and detailed .pdf with schematics for LG G4 H815 which helped in a similar situation. No luck this time, though.
Here are some pictures of what I'm working with at the moment:
View attachment 4866019
View attachment 4866015

Yo igual estoy en busca de schematic del poco ojala alguien pueda ayudarnos

any update on this topic, i am also thinking to reballing my logic board.

Hi all ,anyone have a diagram of the board ? I also have some bad experience with missing one part from the board near LCD connector . which is causing it's dark and no reaction :/
By the way is there some option to make a backup from Poco ? Unfortunately I don't have USB debbuger on :/
Any advice on this ?
Here is a picture of the board with missing part [IMG="https://pasteboard.co/IYtC8mD.jpg"]

While swapping boards, buttons etc from one frame to another i too ripped the mhf4 coaxial connector from the board. I believe that this is a common problem with this board. I ordered replacement connectors from china to properly solder a new one in place.

It maybe a test point......

Related

[Q] HELP!!! broken black wire/connector inside HD2

Hello all.
While I was taking my HD2 apart to replace a cracked screen (glass digitizer) I accidentally broke the connector off one of the wires. The wire is black and a few inches long with a silver and round press on connector on each end. It attaches to the board that houses the vibrator motor and runs down the right side of the phone (if you were looking at it face down and partially disassembled).
Unfortunately, I lost the metal piece that broke off the wire (the thing is tiny!), so I can't just solder it back on. Any idea on where I can buy a replacement? I've spent about 6 hours today on ebay and google to no avail. Searching for "HD2 black wire" and anything similar is hardly efficient, but that's all I know about it.
Any help appreciated.
Thanks,
Chris
Good question, I think I damaged the cable to the volume buttons so it would be cool if someone has an adress where we can get spare parts except LCD and Digitizer..
this guy on ebay seems to be selling an HD2 in parts. you might find what you need here:
http://stores.ebay.co.uk/Right-Click-Enterprises/_i.html?_nkw=hd2&submit=Search&_sid=131407386
Thanks, I sent that guy a message and hopefully it'll work out.
Anyone else have a source?
connector of my hd2 is also broken HTC says that the mainboard must be change and I have to pay € 230 because that is my responsibility
I think you have damaged your coaxial cable connector for wifi and bluetooth. Google will help you perhaps.
I believe that my wifi/bluetooth cable is broken, as I have no wifi or bluetooth signal since dropping my phone as reported in a previous post of mine. Can anybody advise me on the difficulty of undertaking this repair myself, does it involve complete disassembly of phone, any soldering etc. If this is the case I don't feel confident enough to do this so does anybody know of someone who does this sort of repair, I have found the cable on e bay for £7 and it looks like it has push on connectors ?
if the connectors on the boards are not broken then all you need is the coaxial cable with connectors on the two end. you need not disassemble the whole set, just open the back cover, connect one end of the cable to mother board and other end to the rigid flex board and that's it.
WiFi and Bluetooth not working
raincybercafe said:
if the connectors on the boards are not broken then all you need is the coaxial cable with connectors on the two end. you need not disassemble the whole set, just open the back cover, connect one end of the cable to mother board and other end to the rigid flex board and that's it.
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Click to collapse
Do you think that this is my problem as since I dropped my HD2 I have no wifi (unless sat ontop of router) or bluetooth or fm radio, is it easy to get to the coax cable by removing back cover, whereabouts is it ?
raincybercafe said:
if the connectors on the boards are not broken then all you need is the coaxial cable with connectors on the two end. you need not disassemble the whole set, just open the back cover, connect one end of the cable to mother board and other end to the rigid flex board and that's it.[/QUOTE
Fixed it, opened up phone and spotted that at one end of the black wire the connector was not pushed onto the motherboard securely, I pushed it home and hey presto, wifi and Bluetooth now working, phew, Thanks for your help !
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[Q] Please help!fixed power and now no touch screen

Please help, I miss my tablet.I had the common problem with the power thingy inside the tablet going out so i opened it to solder but did not fix.So i ordered the charging dock and waited for a month and a half.I get it today and was so excited to only plug it it and got power and charging everything is perfect,i go to swipe over on my arrow to unlock the screen and nothing!I have no touch controls on screen what so ever.But the soft keys work,they do not do me any good but they work.The home key takes me to my home page and mag glass goes to the internet.Does any body have any ideas of what could have happened or what i can do to fix this,please????
alcapone1130 said:
Does any body have any ideas of what could have happened or what i can do to fix this,please????
Click to expand...
Click to collapse
First, check for disconnected or loose cables inside the gTab.
Next, if it isn't a HW fault like loose cables, then connect the USB cable to the gTab and run this ADB command (you will have to install and set up ADB if you haven't already done so):
Code:
C:\SOME\PATH> [B]adb shell "echo -n 1 > /sys/devices/platform/tegra_touch/calibration"[/B]
Digitizer Cable/Connection
alcapone1130 said:
Please help, I miss my tablet.I had the common problem with the power thingy inside the tablet going out so i opened it to solder but did not fix.So i ordered the charging dock and waited for a month and a half.I get it today and was so excited to only plug it it and got power and charging everything is perfect,i go to swipe over on my arrow to unlock the screen and nothing!I have no touch controls on screen what so ever.But the soft keys work,they do not do me any good but they work.The home key takes me to my home page and mag glass goes to the internet.Does any body have any ideas of what could have happened or what i can do to fix this,please????
Click to expand...
Click to collapse
The attached pdf contains photos of the digitizer/cables and their connections inside the gtab. Check for loose connection and/or broken wires on both ends.
Al
aabbondanza said:
The attached pdf contains photos of the digitizer/cables and their connections inside the gtab. Check for loose connection and/or broken wires on both ends.
Al
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Click to collapse
Ok,First thank you so much for helping.Ok,One of the cables you shown does have two broken wires,it is the kind of short wire with black cloth like material over it that runs unde the shiny brown plastic piece.Is there a way to fix that or rig it to get me back up and touching again?Thank you again for helping me out,and you already pinpointed my problem,now i am hoping you can fix it,lol.
Where is the break?
alcapone1130 said:
Ok,First thank you so much for helping.Ok,One of the cables you shown does have two broken wires,it is the kind of short wire with black cloth like material over it that runs unde the shiny brown plastic piece.Is there a way to fix that or rig it to get me back up and touching again?Thank you again for helping me out,and you already pinpointed my problem,now i am hoping you can fix it,lol.
Click to expand...
Click to collapse
I assume since you didn't send in under warranty for the power connector that it's no longer under warrantly!
Exactly where is the break? Close to (or at) one of the connectors? Which end (motherboard end or digitizer end) of the cable? Obviously closness to the connector makes it more difficult. I have seen a post where another use had the break pretty close to the connector & fixed it though.
Al
I totally forgot that i made a youtube video yesterday,here is the address http://www.youtube.com/watch?v=kFNRtDhr5EQ I have been so stressed out about getting my gtab back it slipped my mind.Oh, the broken end is what plugs under the silver area not under the brown area.
aabbondanza said:
I assume since you didn't send in under warranty for the power connector that it's no longer under warrantly!
Exactly where is the break? Close to (or at) one of the connectors? Which end (motherboard end or digitizer end) of the cable? Obviously closness to the connector makes it more difficult. I have seen a post where another use had the break pretty close to the connector & fixed it though.
Al
Click to expand...
Click to collapse
I totally forgot that i made a youtube video yesterday,here is the address http://www.youtube.com/watch?v=kFNRtDhr5EQ I have been so stressed out about getting my gtab back it slipped my mind.Oh, the broken end is what plugs under the silver area not under the brown area.
alcapone1130 said:
I totally forgot that i made a youtube video yesterday,here is the address http://www.youtube.com/watch?v=kFNRtDhr5EQ I have been so stressed out about getting my gtab back it slipped my mind.Oh, the broken end is what plugs under the silver area not under the brown area.
Click to expand...
Click to collapse
If you magnify the digitizer circuit (lower photo in the pdf) you will see the label for each of the lines in the cable. Assuming the lines run straight thru, it looks like the ones that broke are the power & ground to the circuit (VSS & GND). That would explain the touch screen not working at all.
Hard to tell from the video where the breakis, but it looks real close to the connector.
Your best bet may be looking for someone who has a broken digitizer (outer glass) or gTab and is selling it for parts. I looked in the Marketplace forum here on XDA & there is one non working gtablet someone is asking $55 for. I also saw another one up for bid on ebay ($40 latest bid). You my have to ask if the cable is good on them.
Not a whole lot of options for repair. As you've already experienced, the cable is small & fragile.
If the connector has removable pins then you could remove the pins, solder the wire to it & reinsert the pins, BUT from the picture it doesn't look like they are removeable.
You could solder the 2 wires to the pins coming out the back of the socket but they look too small to easily solder to.
The last option would be to rigg the cable to work. There are a couple of possibilites but I would rather you consider the other options before suggesting a repair of the cable itself. If you can, see if you can take a closeup, high res photo of the back fo the connector where the wire broke. PM me & I'll send you my email address to send it too.
Al
aabbondanza said:
If you magnify the digitizer circuit (lower photo in the pdf) you will see the label for each of the lines in the cable. Assuming the lines run straight thru, it looks like the ones that broke are the power & ground to the circuit (VSS & GND). That would explain the touch screen not working at all.
Hard to tell from the video where the breakis, but it looks real close to the connector.
Your best bet may be looking for someone who has a broken digitizer (outer glass) or gTab and is selling it for parts. I looked in the Marketplace forum here on XDA & there is one non working gtablet someone is asking $55 for. I also saw another one up for bid on ebay ($40 latest bid). You my have to ask if the cable is good on them.
Not a whole lot of options for repair. As you've already experienced, the cable is small & fragile.
If the connector has removable pins then you could remove the pins, solder the wire to it & reinsert the pins, BUT from the picture it doesn't look like they are removeable.
You could solder the 2 wires to the pins coming out the back of the socket but they look too small to easily solder to.
The last option would be to rigg the cable to work. There are a couple of possibilites but I would rather you consider the other options before suggesting a repair of the cable itself. If you can, see if you can take a closeup, high res photo of the back fo the connector where the wire broke. PM me & I'll send you my email address to send it too.
Al
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Click to collapse
Wow,Thank you so so much,Can you get me in contact with the guy with the gtab for $55.00,i will buy it and transfer the cash to him immediately,that sounds like the best bet.I will msg you a really good photo still,incase i can not get my hands on the one for sale,but if i can let him know or maybe you could let him know that i will buy it quick enough maybe i can end up with it.I would really feel better just swapping the cable out with another.I will talk back with you tomorrow and again thank you for your time and great help,i really owe you.
Marketplace & Non Working Tab Links
alcapone1130 said:
Wow,Thank you so so much,Can you get me in contact with the guy with the gtab for $55.00,i will buy it and transfer the cash to him immediately,that sounds like the best bet.I will msg you a really good photo still,incase i can not get my hands on the one for sale,but if i can let him know or maybe you could let him know that i will buy it quick enough maybe i can end up with it.I would really feel better just swapping the cable out with another.I will talk back with you tomorrow and again thank you for your time and great help,i really owe you.
Click to expand...
Click to collapse
Here are several link for you
1. XDA Marketplace http://forum.xda-developers.com/forumdisplay.php?f=1321
2. Link to "Wanting to sell" subformum where I found the non working gtab (used forum search for gtablet) http://forum.xda-developers.com/forumdisplay.php?f=476
3. Link to not working gTab http://forum.xda-developers.com/showthread.php?t=1436549&highlight=gtablet.
Take a look at this post & email him to make sure you want it.
Al
aabbondanza said:
Here are several link for you
1. XDA Marketplace http://forum.xda-developers.com/forumdisplay.php?f=1321
2. Link to "Wanting to sell" subformum where I found the non working gtab (used forum search for gtablet) http://forum.xda-developers.com/forumdisplay.php?f=476
3. Link to not working gTab http://forum.xda-developers.com/showthread.php?t=1436549&highlight=gtablet.
Take a look at this post & email him to make sure you want it.
Al
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Click to collapse
Its amazing what a couple of stripped bread ties will doo,lol.I took a bread tie and stripped the paper off of it,cut it to the length I needed and wrapped the remaining wire to one end and pushed the other end of the tie inside the pin hole,lol.It worked like a champ! MY Grab has been up and running for over a month,I just knocked on my coffee table,lol.Thank you for helping me out I really appreciated you trying everything to help me.I am so happy to have it back,now if I can just figure out why I keep seeing black boxes on my games when I play them I will really be doing fine.Thank you again.

[Q] LCD not working; logicboard, flexcable or screen?

Hi all,
Recently, I bought a Sony Xperia Tablet Z of which the previous owner had removed the whole screen. Tablet was working, then he dropped it, causing the screen to be broken (LCD was blacked out, tablet and digitizer/touch still working). He removed the screen assembly as a whole, had the intention to replace it but he just sold the rest of the tablet.
So I obtained an LCD/digitizer assembly form AliExpress, but after installing the screen and switching on the tablet, I got the same problem: Touch is working fine, tablet switches on nicely, I get some kind of 'blind-modus?' that responds to touch with sounds, it tells me I'm swapping through menus, but the LCD itself does not give any signal. Linking it to PC works fine too. Linking it to a TV requires an MHL cable, which I don't have...
My question is:
Does anyone know if this is a well-known problem after dropping an Xperia Tablet? I'm more or less sure it's not the LCD of the replacement screen that causes the problem (given the background), so the problem might be in the LCD flex cable, or worse, the logic board. But how to find the faulty component?
For the flex cable: I've tried to measure (multimeter) the resistance of the wires between each tiny pin of both the connectors of the ribbon, but it's not easy. Some pins on one connector are linked to multiple other pins of the other. Is there an easier way to check this, anyone any experience with this?
If it's the logic board, is there any way to make sure which component is broken, and is this fixable?
If it might help: I have a set of pictures of the logic board / flex / LCD.
Otherwise, I might just try and stop by a tablet/phone fix shop, ask kindly if I could quickly check one of their screens/cables to verify which parts are working/broken.
Thanks in advance!! Kind regards
Edit: I just noticed there is a specific forum for Xperia Z (one), this thread belongs there, sorry! Could this thread be moved there?

[Q] help battrey ribbon

Help took back off my hdc s6 clone to see what battery was in to see about changing it and a ribbon from the battery snappednot sure how you get to where it goes and can I get a replacement if needed
thanks
A ribbon? you mean like the connector 'cord' to your logic bord snapped?
yes basically its that have got the other end off now. But when looking at battreys they all seem different mine as a circuit board on the end with a longer ribbon and the port is side off the battery almost in the centre

USB C Port Not Charging, Recommendation for Replacement?

Hi All,
I have a Nokia 7.1 that stopped charging. I cleaned out the charge port and tried different cables and adapters but nothing worked. I've since come to find out that it's a common enough problem that lots of people post about it on Nokia's support forum with no other option other than taking it to a service center. I'm in the USA and there's not a single service center in my state so I decided to try and replace the daughter board myself. I've done this kind of thing before on other phones, my Nexus 4 was a frankenstein's monster by the time I was done with it.
My problem is I can't find a reliable source for a quality part. There's tons of replacements on amazon, ebay, aliexpress and other random sites but all the ones I've read had issues for connectivity of cell service or wifi. Does anyone know where I can source a new daughter board for this phone?
Any help is greatly appreciated.
Thanks!!
I went through the same issue.
Bought another type c charging port on Amazon, it still works.
Awesome! Thanks for the reply. Did you go with one of the ~$10 ones or one of the ~$20 ones?
My 7.1 developed the same problem. What is the root cause? Is it mechanical problem of the connector pins worn out/oxidized? It does seem to be a mechanical problem since I can still wiggle the cable to make it charge for a while. What puzzles me is that the USB-C has inherent redundancy with 4 power and 4 ground pins that it should not easily fail. I have a phone with the old micro-USB and the charging still works flawlessly.
lejaune said:
My 7.1 developed the same problem. What is the root cause? Is it mechanical problem of the connector pins worn out/oxidized? It does seem to be a mechanical problem since I can still wiggle the cable to make it charge for a while. What puzzles me is that the USB-C has inherent redundancy with 4 power and 4 ground pins that it should not easily fail. I have a phone with the old micro-USB and the charging still works flawlessly.
Click to expand...
Click to collapse
I'm not sure. It does seem to be a mechanical problem, but I've seen some repair videos where they open it up and just run a soldering iron over the connector pins on the board and it starts working again. I've ordered a daughter board and a replacement back glass panel in case I break it trying to get it off. I'll update after I get the parts and open it up to see if it works.
The board I ordered was this one from Amazon Smile:
https://smile.amazon.com/gp/product/B08166DLDC/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
It seems like the ~$10 boards are missing some chips that the ~$20 ones have, at least according to the pictures that were uploaded with the listing.
@bpowdhar, Thanks for the quick reply. I did order a connector board on Ebay, and it looks to be of the ~$10 variety. I'll see how it works when it gets here. I will also try the "melting the solder" trick without removing the connector first. If that works, I'll leave the old board in place just to minimize the risk.
So I received the USB-C charging board and replaced the bad one. Now, it seems to be charging normally. It took some work to open the back cover by heating to soften the glue/tape around the edge. I then used an a xacto knife to pry the corner open followed by dragging an old credit card to slowly separate the cover. Once it's open, everything went smoothly. Just watch one of several Youtube video clips to know what to expect. You do need a small Philips screwdriver and a #5 Torx driver. You need to lift a ribbon cable and a micro coax cable from the board. Just don't forget to put them back on to the new board. I didn't bother to fix the old board by re-solder the connector pins because they are way too small for my solder iron.
I rely on the existing glue/tape to glue the cover back, but I'm sure it's not as water/dust proof as before, so I may redo that part to clean the old tape out and use the new tape or glue when I have more time.
I do noticed a couple of parts missing on my $9 board. I don't know if they have anything to do with regulating the high voltage fast charging. I usually charge the phone with a 5V adapter, and I will stick to 5V, at least for now.
Thanks for the update! I'm still waiting for my board to arrive from Amazon. It was delayed with the new shipping date anywhere from Nov 5 - Nov 10 and it still hasn't arrived. It sucks because tracking info shows that it arrived at my area's sorting facility on Oct 29 and left it on Nov 4. So it should have only taken a day or two to get to my local post office and to my house. I'll update when it finally gets here.
I know it's been a couple of months, but I finally got the part and swapped it out yesterday. The battery was completely dead so I plugged it in to charge and left for the day. I came back to it this morning and it's at 100% battery! I'm so happy now! I've attached a couple of pictures showing the old board (with the red dot) and the new one. So far no connectivity issues, but I'll give it a couple of weeks to see if anything changes.
A couple other notes:
It was surprisingly easy to get the back glass off. I used a heat gun on low and ran it around the perimeter for a couple of minutes and a utility knife to cut the adhesive. This part was what I was most apprehensive about tackling.
The fingerprint sensor comes off the same way, apply heat and press / pry away from the glass to reuse.
If I had to do it again, I'd buy the tube of sealant. The replacement glass came with a set of narrow adhesive strips and those were a pain to deal with.
Thanks to everyone who contributed to the thread. Hopefully this helps someone else.

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