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Battery Drain

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xdanubi

Member
Dec 6, 2011
17
0
Samsung Galaxy Tab S2
LG V20
Be careful with the screws. The screws are all different length, and when I opened mine I was following a guidance that there are two groups, but found it to be wrong as my phone seemed to have at least four groups of different screws. It was too late, however, because mine were already mixed within two groups I created. So, I would advise to create a diagram of screw location and keeping track of which screw goes where. I think that many times this phone is taken apart and put together, without this tracking, some screws end up too long for where they were placed and holding parts loosely, thus adding to the flex that might be cracking the older brittle thermal interface.
Don't worry, I'd use soldering silicon mat that have tiny rectangles area to store the screw. I am to scared to grouping the screw by it's size, so I just separating the screw, and put back where it belong.
 

xdanubi

Member
Dec 6, 2011
17
0
Samsung Galaxy Tab S2
LG V20
Since Iam only an amateur, I am considering building a DIY usb webcam based microscope like the one EEV blog had reviewed or better.
That's interesting. I am subscribed to his channel, but it seems that I am away from youtube in last couple of months. I am gonna search that microscope alternative.
I do plan to buy some of single, cmount type lens, coupled with cmount based camera. It's cheaper than bino/trinocular out there. i do have some crappy cheap usb microscope that do indeed magnify something, but doesn't have enough distance to work with, so I am stick with magnifying glass for now.
 

Descent2

Senior Member
Nov 1, 2012
65
11
California
LG V20
I'd use soldering silicon mat that have tiny rectangles area to store the screw.
Whatever method works, of course. I have exactly same mat, and place screws on the left edge into numbered compartments. However, if I take a while to mess with something, sometimes I'll touch the screws in cells with the bottom of my arm and they stick to it.Then they fall off in the middle of the mat (lucky me) totally surprising me, lol.
 

Descent2

Senior Member
Nov 1, 2012
65
11
California
LG V20
I am subscribed to his channel
It is nice that so many people on XDA are totally the type of folks I'd be proud to have as friends. I too watch Louis Rossmann of course. Btw, funny, recently watched Louis Rossmann video and noticed that his YouTube feed looks so much as mine that I'd have a hard time telling which is which!

The EEV Blog video I was talking about is this one:
Code:
https://www.youtube.com/watch?v=HIWUFFlr2I4

I have just received the MS cam from eBay for about $20. Just need to get that lens
Code:
https://www.diyinhk.com/shop/usb-microscope-1080p-for-smt-soldering/51-lifecam-studio-1080p-microscope-lens-mod-kit.html

or replace it with something on my own.

I am sorry for the chaotic nature of my posts. The main issue that you have is the dark current, like you said. You are right in that the fact that you can feel that extra consumption in the heat dissipation is better than if you didn't, - you'd have the chips cooked. So, all the other things are just areas to improve on, but finding the exact component responsible for your higher than normal current consumption is the key.
 

xdanubi

Member
Dec 6, 2011
17
0
Samsung Galaxy Tab S2
LG V20
Could you show which area was heating up:

View attachment 5379123
I tested on the other side., because at first I thought there's some bad capacitors.
This one right there heat up pretty fast, even though the screen unplugged

v20.jpg
 

xdanubi

Member
Dec 6, 2011
17
0
Samsung Galaxy Tab S2
LG V20
It is nice that so many people on XDA are totally the type of folks I'd be proud to have as friends. I too watch Louis Rossmann of course. Btw, funny, recently watched Louis Rossmann video and noticed that his YouTube feed looks so much as mine that I'd have a hard time telling which is which!
I am happy too, having a total stranger, responds to my problems, and patiently explaining something new and valuable knowledge to me. I am very appreciate that.
By the way, what is your yt channe? if you don't mind sharing it here.
The EEV Blog video I was talking about is this one:
Code:
https://www.youtube.com/watch?v=HIWUFFlr2I4

I have just received the MS cam from eBay for about $20. Just need to get that lens
Code:
https://www.diyinhk.com/shop/usb-microscope-1080p-for-smt-soldering/51-lifecam-studio-1080p-microscope-lens-mod-kit.html

or replace it with something on my own.
I think I'll pass on this one. That one locked set of zoom is really tuning point.

I am sorry for the chaotic nature of my posts. The main issue that you have is the dark current, like you said. You are right in that the fact that you can feel that extra consumption in the heat dissipation is better than if you didn't, - you'd have the chips cooked. So, all the other things are just areas to improve on, but finding the exact component responsible for your higher than normal current consumption is the key.
No need to be sorry, my post just as chaotic as yours, even worst, my grammar is not that good to begin with.
The phone can dissipate that heat without cooking anything, yet. It can stay on a whole day, pluged to the charger of course, without any smoke coming out of it. While it definitely doesn't comfortable enough to hold on, because of the heat, but the main problem having it as a phone was the blazing fast battery drain. Having 0.6A of dark current, the phone just lasted an hour or less with the battery plugged. So currently I have it stanby with battery removed, on only turn it on when I need it. The unfortunate part was that I have two finance app that lock to that phone.
 

xdanubi

Member
Dec 6, 2011
17
0
Samsung Galaxy Tab S2
LG V20
You clearly have about 0.3 A to 0.6 A dark current. Something is consuming this energy and dissipating it into heat. When capacitors are shot they now represent a short on the circuit where there not supposed to be one. Such short will now create this dark current.

Capacitors fail due to old age, high heat (vicious circle), and bad power supplies that deliver spikes and poorly filtered power. Big electrolytic capacitors dry out, explode, leak, but SMD capacitors fail too - they crack and melt.

Code:
https://www.youtube.com/watch?v=IciwMsWX_Y4

There could be other failed components, it's just that capacitors are ubiquitous in this regard.
I begin to suspect other things too, even the software part was suspicious.
Do you have any reference of how much cpu usage stock standar V20 on pie? Mine was pretty suspicious, and the strange part, this is happen even after flashing kdz file.

Screenshot_20210806-122711.png


Is this look suspicious to you? having a quadcore cpu that have almost 8 cpu load on all 5,10,15 min average. The phone was turn on and stanby for 13 hours. I don't have any "heavy" apps on it. I even de-google it, remove the known hogging apps like facebook, instagram, and any other preinstalled. The phone still un-rooted.

Do you have any other unrooted apps that I could try to analyze this strange cpu load? I randomly try "Simple System Monitor" and this is what show up.

Screenshot_20210806-122403.png


Screenshot_20210806-122410.png

Screenshot_20210806-122416.png
Screenshot_20210806-122421.png
Screenshot_20210806-122427.png
Screenshot_20210806-122441.png


I just have one V20, so I don't have anything to compare.
On my other android that have octa core cpu(galaxy tab s2), and much more apps on it, the cpu load was llike two point something on stanby.
 

Descent2

Senior Member
Nov 1, 2012
65
11
California
LG V20
I do not have a YT channel for this topic.. I am sorry for misunderstanding, I meant that his "feed" is the same as mine. Meaning that his interests are exactly matching and I recognize like almost every video. I have a channel but it is about birds and quite ridiculously stupid one, so, same as I don't have any, lol.

The shield that you have circled covers the "power supply" of the phone. Under that shield is the PM8996 chip which controls the power. It basically looks like this:

SM-G935F POWER&BATTERY OK.png



This is a samsung board, but the chip is the same. It is marked U7003 yellow. You can see where the shield was soldered - I marked those spots with small green left leaning slashes. Around that PM8996 integrated circuit you can see smaller parts. The ones with smoother lighter coloring are usually the capacitors (I marked few of them with a pink dot). One of them is probably cracked and shorted. Also note how there is a wire inside the board (marked by orange line) that connects the power button to the power supply. This is the connection that explains why your phone likes to start by itself when you provide any kind of power. I think that the capacitor that is shorted somehow makes it so that the voltage gets to the pin of 8994 which normally is the "boot the phone" signal.
 

Descent2

Senior Member
Nov 1, 2012
65
11
California
LG V20
I totally agree with you that your screenshots show that things are not right. However, unfortunately, we know that your phone is misbehaving even while it is OFF (draws current, heating up, boots up). This is very important as it means there is a hardware issue.

Now, the software will do something crazy easily for several reasons, bad hardware being one of them. It is no wonder the phone software behaves like this if it has issues with power. I would not focus on that till the hardware issue is solved, because there is no point. To troubleshoot software, the hardware must be running fine as a pre-requisite. And you are way ahead of me in knowing which apps to use, anyway.

Now, to lift the shield and hunt for bad part, and possibly replace the entire PM8996 chip is going to cost you dearly, I think no less than a 100 dollars, just because of time and labor of a guy who is capable of replacing the chip. Add shipping if you don't have a shop nearby. Obviously, you'd be better off getting a replacement phone. Maybe a master in a lower wage country? Depending on where you are. Here in USA, this makes no sense, because the repair would be more than a replacement device. Check how much Louis Rossmann charges for this?

Make sure you have the backup now because this power issue might get escalated all of a sudden if another part fails due to thermal situation. I think if another component fails the phone will no longer boot.

I am sorry to say, my friend, but after we dug this deep, this situation looks bad. I no longer think your USB port has anything to do with this. Nor thermal compound on CPU, nor any software issues. Everything points to things under that shield (confirmed by the uncontrolled boot on power connection).

Or I am not thinking straight. If something else comes to mind I'll post it here.
 
Last edited:

xdanubi

Member
Dec 6, 2011
17
0
Samsung Galaxy Tab S2
LG V20
That's very make sense, a bad pmic, or anything around it. I am okay with cracking / lifting those shield up. In fact, I am in the position of nothing to loose, because the phone pretty useless at this point. It is boot up, I can use it, but the battery only last one hour, plus the excessive heat. The finance app that tied to this phone, I can go to the bank next week to pair it to other device. It is annoying, but doable. Anything else was already move to other device.

If the bad part was only some caps, then I am lucky. If it was the ic, then I'll rest the device until I have enough tools and skill to do the rework. Sending it to repair make no economical sense at this point. I got this phone for 1 M idr (around 70 usd), and I am not sure I can find local repair shop that do board level repair. Might as well to just add it to my "bad phone" collection. This is the first LG :D.

Thank you very much for accompany me this far.
 

Descent2

Senior Member
Nov 1, 2012
65
11
California
LG V20
If you want to go there then you'd need the hot air station to de-solder the shield, unless you are pretty deadly with your iron. Will have to wait till you get a new magnification setup, cause it's all super small under that shield. I would like to know what microscope you ended up building and how well it performs. It will probably make sense then to test most of the components that are available just in case the heating up part is not right next to the failed part. I've seen YT videos on checking the SMD components and some of those guys don't even replace the bad capacitor once found, they just break it off and thus remove the short, and give the device back to client. Of course, since the capacitor was there to tune some circuit or filter some current or signal, the device would still work, but possibly not as good.

It was my pleasure. Good luck
 

xdanubi

Member
Dec 6, 2011
17
0
Samsung Galaxy Tab S2
LG V20
I am buying cheapest scope available with interchangeable c-mount lens, and I start to regret it. It's 1,3 mil IDR (around 90 usd), the same price as the phone it self. The cheapest, phone repair standard binocular start at twice that price. But I should go for that instead of this. I'll show you how it's perform when its arrive.

This is the url of the product at my local marketplace.
Damn I shouldn't buying this
 

Descent2

Senior Member
Nov 1, 2012
65
11
California
LG V20
OMG yeah,that's expensive! I guess you love your phone so much you don't care what it will take to fix it! Man, you're a fighter :)

But, the scope seem to be good. Up to 130x magnification (so 65x by recommended monitor, and x2 by the lens itself). I am curious about the depth of field at the highest magnification level.
People say it takes a little to get used to. Because unlike in binocular scope, you are looking in a direction different than the direction your hands are working at. Some had to place a monitor between their eyes and their hands. Something I too will have to get used to, as I don't want the bi or tri ocular system. Just too much cost and space for an occasional repair.
 

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    Hello ROMSG,

    Can you confirm the battery is drained vs being read as drained? You could try measuring the voltage on battery contacts before and after to confirm.

    Or, since this would not hurt, without even confirming, for fun, try and clean out your USB port and the C end of the USB cable with strong alcohol, and then compressed air. Dry for sure - leave it in the sun for a while laying on or right next to some table salt.

    Why:
    I just finished analyzing a thread with unrelated issue, but there, it seems to me that bad USB port was causing get this: low reading from otherwise good battery (or actually create a drain - dark current on the USB connector itself). No idea why, but must be connected somehow.

    I had re-soldered USB port twice in the past and once the power switch on my own devices, so it would not surprise me at all that those internal components would fail. And I am kind of super precise in how insert the cable, just time, I guess.
    1
    Funny how things work. Today I received a phone I bought from eBay for $50, because it was "Google FRP Locked". Mint black H918, no water damage. I thought I'd use the LGUP to re-load the software and may-be make it work, or something, you know, for practice learning about this stuff.

    Well, it would not boot past the T-Mobile screen. Finally I made it boot to Factory Reset screen, pressed YES and it went black. No more boot, as it reported the battery (which was about 70% full before this) is now at 0%.

    From 70% to 0% in a few unsuccessful boot attempts? Wow, that's really something. It did not get hot.. So, where all that energy went? I mean how did it dissipate 11.9 x 0.7 = 8.33 Wh ? It took about 15 minutes if that, so it was dissipating at 4 x 8.33 = 33.32 Wh speed without even getting hot? That's insane.

    Anyway, the USB connector looks horrid, and the charge percentage is going ON and OFF when in the USB cable is in it. The USB cable feels loose in the port.

    I tried cleaning but it is too far gone. I am going to replace the USB connector with a new one.

    But do you see, again, the same link between discharging the battery / bad USB port and boot-loops? If true, this means that there might be a sea of perfectly good phones on eBay, just with bad USB connectors, boot-looping and eating batteries. Re-solder the USB port and you're good to go!

    I would be excited to find out what was your result.
    Lg up typically causes battery drain but not like what you described. Also reflashing wont fix frp in all cases, since the versions of android on these devices is so old frp bypasses are typically a better route. I know from expierence.