All right, new day, new laptop repair. This time we have an XPS 9700. But let's see what's wrong with it. The customer said that he changed the battery following a YouTube video, and at first it will not turn on, it kept flashing between white and amber.
He let it charge overnight. The next morning it wasn't turned on at all, so please help. All right, so let's figure out what we got here. So XPS 9700. This is a 17 inch laptop.
Here's what we'll do. First is we're going to let me plug in the charger real quick. And we've got 20 volt negotiation.
No current being drawn. Let's let's try another port. So the PD controller is working the PD controller is actually negotiating the, the voltage, but the laptop is not taking the voltage. So that could be a power management chip or something like that. Let's take a look and see if the laptop will power on.
We got an orange light. So that usually means the battery's dead. Plug this back in. Okay.
I'm going to hit the power button. Nothing happens. The current doesn't change either. You can't really see that. Let's see. Let me use this camera.
See if you'll be able to see it with this camera. There you go. Okay, so it's not pulling any current from here. We don't have an orange light anymore. I'm going to press the power button and see if it changes.
And I don't see anything changing. .03. That is basically just the IC chip powering up. So it's not enough current for anything to happen. Oh I'm seeing the screen kind of flash for a second actually I don't know if you can see that. It's like the backlight is coming on temporarily and turning back off.
That's interesting. Well, we're gonna have to open the bottom up and figure out what's going on. Since he changed the battery out, we don't know what he did if he unplugged anything else in there.
So let's open up the bottom here. Okay. These bottoms are hard to get off, but since it has been off at one point, it makes it a lot easier. Okay. And so we have it open. So let's take a look here. Here's the battery.
It looks like it is a genuine OEM battery. It does have a serial number here. That's something that's important to know because aftermarket batteries have an issue. This battery is just like a pull latch here. See that connector? It's a little bit different than any of the other batteries that go to this.
The first thing I'm going to do is actually just grab a test battery, because I have some of these as test batteries, I can just grab one. All right. Here we go. So I have a test battery. What we're trying to test here is to figure out if the laptop will still power on off the battery.
Okay. Got the battery out. This is his battery. Plugged in. I actually don't know if there's a charge on this, but we can figure it out pretty quick. Not seeing anything happen there. All right, here's what we'll have to do, because this isn't I don't think this battery charge. I'll grab a test board, which I have lots of other boards there.
And this board is the same model for same type generation. I'm gonna plug it in here. And we'll plug it in. It just let it charge up for a little bit.
So I've let this battery charge for a little bit. It's a little let's see have charge this and see if we can power up the system here. So here's the customer's laptop. I'll go ahead and install his battery back in there. We'll see if we can get his laptop to power up on his battery.
Now that it's charged a little bit. I don't see any lights yet. Chargers not doing anything. There we go. We do have lights here.
Let's see if there's a light code of some sort. One. Two three. One. Two three. Four. Five. Three. Five.
All right. My codes for XPS 9700. This says three five. Power rail failure. So I was wrong. It's not a Bios. It's a power failure.
All right, so we got to figure out which power rails actually failed. Let me go ahead and get this board pulled out. And that way we can start doing our measurements. Actually, I may not pull up the board. I'm just gonna take the heatsink off and we'll pull the hard drive. And that way we can get down to it, and we might be able to not have to pull the board out.
You know, it's interesting is that I see something. Oh, I did not see that earlier. Okay. All right. Okay. All right.
So you remember earlier how I talked about how it's hard to get this off, and it came off pretty easily. And that's because it has been open before. Let's take a look at this. I don't know if you're gonna be able to see it, but look right here. You see this is dented in.
This is dented in, this is dented and this is dented in the fins are dented. I'm assuming that somebody was trying to pry the bottom off by sticking a screwdriver in here or something like that. That's the only thing I can think of. And I bet that that bent something that's shorting something out, because seeing these on here, this is pretty crazy.
So there's bends there over the. So let's pull this thing off. Let's figure it out. All right. Got it. And it's off.
All right. You can get a closer look at this. So this heatsink will need to be replaced. Yeah. That's no longer usable. So if we can get the focus, thermal paste.
I think this is the original thermal paste. I don't think it's been changed. See, that actually is pretty dusty, so I don't think he has opened it up to clean it, to clean that out. I think I could send this over to the greatest technician.
Do you think he wants this stuff? I'll collect it over here. We can mail it off to him tomorrow. Okay, so let's go ahead and take a look at these power rails real quick. If something is shorted, it should be pretty noticeable. So I'm putting this probe and beep mode. So one on ground.
And I'm just going to check some of these coils here. And that's fine. So you can see right there there's nothing here 35Ω. 35Ω is probably okay for that. So this one's okay.
What about over here? So this is going to be a 3.5V rail over here. So it's going to measure that. That's fine.
That was fine. And then there's I think there's another 3 and 5V over here too because each side has its own. There they are.
You and I'm not seeing anything shorted here. Let's go ahead and plug the charger in now that we have the heatsink taken off. I mean, the heatsink could have been bent in a way that was actually shorting out some of these parts here. So let's check that. All right. Got it plugged in.
Still it's still not charging but we don't have a battery in there actually. So let's see if it starts charging close to the. Yeah I was just looking here to see if any current changes through all that one. Nope.
All right. I'm just going to measure some voltages for this on volts. Got zero volts in the three zero volts in the five.
Think this is the main power rail now at 000 everywhere. I need pull this board out. There's nothing I can do, trying to do this. So give me a second.
Okay. When the board is out. So let's go ahead and do some measurements real quick. Now that we have the board out, it will turn on by itself, for a CMOS reset. If it is going to turn on and I don't see anything happening here. Let's do a physical inspection. Make sure we don't have any blown out components or anything like that.
okay. I'm just looking around the board. What I'm looking for is anything that looks suspicious. It could be a burnt. It could be a spill, be a burn.
But since he changed the battery out and there's a missing power rail, it's most likely going to be some sort of shorted component, which could be a cracked capacitor even. I don't see anything so far. Just going to keep looking around. Oh, this looks fine. Check the other side again one more time.
This is where all the actual power components are. There’s switch there. So we're going to look around to see if there's a shorted rail. All right. So I'm going to go back to beat mode, continuity mode. I'm going to do a little look over here real quick.
So just check some of these capacitors over here. That's fine. That's fine. Fine. That's fine.
Let's look over here. So this is the same setup. You can see it looks the same as over here. Or is it that right here? See.
The board is setup where it has it on both sides. So the positives on that side. All right so let's check this.
Another audio chip here. It looks fine on the audio chips. Let's check this current sense resistor.
See most likely there's no shorts. But we need to figure out which power rails not actually coming up. All right. So the input circuit is right here.
All right. Let's see if we have the main power rail. So these are the MOSFETs that power this GPU here.
And these capacitors will be on the main power rail here. And we've got 0.8V on the main power rail. I would say that's not enough. So you have those and I would say that's not enough. We do have 20V here. 20V coming into this MOSFET.
20V coming out of this MOSFET. Nope. Okay, so this.
Do we have 20V going into this one to. So 20V is here and that goes into here. And then that's going to come out.
And it looks like that powers. Oh this is ground right here. So and then this will go I got .5V on this side.
What do we have on this gate. What do we have on the gate on this one zero. All right, so this power management chip is what's actually going to be using taking the voltage from the charger cable or from the usb-C. And then it will be controlling the MOSFETs to, to create a main power rail.
And then it will also, charge a battery. So let's see. We'll get measurements there. I actually have more of these chips if I need it. If we need to replace it. 19V coming in, 19V should be there I think 20V. Yep. But this is all looking fine here.
I am pretty sure we're supposed to have five volts here too. So why we don't have five volts, I don't know. So let's figure out if we can figure out what's, what's supposed to be on that.
So what I'm going to do is I'm gonna take a board that works, a functional board. All right, so here's a functioning board. That way, we can figure out what voltage is supposed to be on that pin. So we measure here. We got 20. And what do we have here? Four volts, over here 3.3.
So we're missing 3.3. So let's go back to the other board. So this chip's not getting the 3.3. So if we measure right here oh we have a 3.3.
How do we miss that. This one's not 3.3 though. Yeah. All right. Let's figure out where those voltage sources are being generated and created. Oh well so here's the customer's board again. And.
Let me see if I can pull up the board view schematics. All right. It's another day. I had to end yesterday. I didn't have much time. Okay, so let's let's continue looking at this.
We were looking at the power management chip because we measured we have 20V going to the chip, 20V going in. And then on our other board that we were testing we had 3.4 here. But we don't have that. That's missing. We have 3.3, 3.3. We're supposed to have 3.3 on all these.
This one's not supposed to have anything. And then and 3.3 on this one. So we're actually missing 3.3 all the way across here. 0.4..... I think this chip's bad. I think we're just going to change this chip out. That'll be the easiest route to start with.
These things go out, I have more of them. So... I got two left. There it is.
All right, so let's remove this chip and move it over. And see, these pins are getting shiny here. So we put the shiny it’s almost ready to come off. Those two are still not shiny. There we go. About three. There we go.
Can loose and it's out. Let's put some fresh solder on those pads. So this is a lower temperature solder. Better quality. I don't want much in the middle.
Then we're just going to heat this until everything gets shiny. And then we'll be able to set that down and see how the pins are getting, all the solder is getting melted and become shiny. So. We'll add a little bit of flux. And there we go, it just seated itself. So.
Okay, that is soldered on. Let's go ahead and clean it up. Cool it down a little bit and we'll give it a try okay.
Let's plug it in and see what we get. Let's go ahead and measure around that chip. See if we have that 3.3 or if it's still missing. We still don't have the 3.3 here.
Or the 3.7 there. We got our 20 here. Still got the five volt there. Five volt. We have the five volt here. Still five volt going in there.
So the issue is not in this area. So that that chip is actually fine. I'll probably end up putting it back on. All right. So here's what I figured out so far.
So all the power rails actually are present but for a short period of time. So if I plug it in. And I measure the main power rail.
We get 13.3. If I measure the five volt we have five volt. If I measure 3.3, we get 3.3. If I measure the 1.2 for the memory, I got 1.2.
If I measure the chipset, we got the chipset, hold on, let me start it over again because it only lasts for a few minutes. And then it shuts off for a few seconds. So I'm going to plug it back in. Chipset is up. Memory... memory is up. So all of them are working and then it will shut off.
So we'll just stay on the main power rail here. 11.8 this is actually be 13.6. And see it drops off and then now it's dead.
So I'm going to reset it. Plug it back in again. 12.56 goes down to ten goes to 13.2. And it starts dropping down again. 11.86
And it sits there for a little while. And then that whole power rail shuts off. There we go. And now the board is off again. So, the power rails all work except the main power rail keeps shutting off. Why is that? So if we take a look at these two MOSFETs and this coils, what produces the main power rail from the 20V coming in through here to this current sense resistor.
And so if I measure right here, which is the output of this MOSFET. You get the 12.86, I mean the 13.3. And then it starts dropping down.
But what I'm interested in is what's on this gate pin here. Because the gate pin is what dictates how much voltage is going to come out of this. So I'm going to reset it again. This should be higher than what we need.
So it's 12. It only gets up to 13. Then stays 11. So ideally that pin should actually be like at 16 or 17V to allow the 13 to be able to come out of here. So there's a chance that this MOSFET is actually shorted to that pin to that gate. So let's go ahead and measure.
Let's see if we have a short across these. And we do have short I measure this one to. This one the resistance low. And then going back up. So we'll go back to this one. This MOSFETs probably shorted out.
And that's why what's causing this gate pin to stay the same voltage rise it turns on. This actually should be higher. So a lot more to come out. So let's replace this.
All right. Solder starting to melt. You can see it there on the loose okay. And it's out. We are going to install one of these N-channel.
Okay. It's going to go that way. Okay. Let's see.
Is it going to work? Still nada! Still nada. Reset the charger. Let's see if we can get that same 13V there. 12.55 through 2.3 drops down to 11. Same same.
And so we've already replaced the parameters of a chip on this. So what component over here is causing the issue. I'm going to look around again for a short because there's something there's something that's preventing the that. It's like sensing that there's an issue. And so it's not allowing the voltage to get there. I mean, the fact that this happened after the guy changed the battery.
It's very interesting, but I kind of want to get a story to figure out why he was changing the battery. Because that could have something to do with it. Looking around the board, see if we see anything out of place. And what do we have here? So this component that got ripped off the board here, looks like this pad's missing completely.
This will definitely cause an issue. How did this get ripped off? I'm not sure. This doesn't make sense, because remember, we saw this damage here, the heatsink was bent from a screwdriver being prying it off.
But the heatsink goes on like this. And this motherboard installs like this. So the broken component is underneath this. Okay.
Let's take a look. I don't see anything per se. So what would have been like right around here? I don't see any big pry marks, but I can imagine a screwdriver shoved in there deep enough. It would end up prying underneath the motherboard right here. All right, let's replace that component, see if we get this board. The boot up.
Hopefully one of my donor boards has this chip. So we got the donor board. I have for this hole. Wow.
That's why this is the donor board. It's a little different in this area. It looks like it's the same set up here.
Resistor. Two pads here. Yeah, I think that's the right one. So let me go ahead and prep the area real quick. So this will need to be, we will need to put a new pad on this. let's go ahead and do that real quick. So we'll I'll need to do is I'll scratch this away.
To reveal something to solder to. Like That. Sure. Need to break off this extra little piece here. Like that.
To clean these rest of these pins. With fresh solder. Okay, ready to go. Let's put the new chip on. I'm going to steal it off this other board. That has a hole in it.
Okay, we got it. We got it. Let's go ahead and clean this up a little bit. Blue. Okay.
Okay. Let's see if it works. Now. Okay. You ready? Here we go. Moment of truth. It's pulling.
Look at that. All right. The board looks like it's POSTing.
So let's go ahead and get it reassembled in there. All right, it's back together. Let's see if it works.
See if it works. Plug in the charger. At 20V, you got a Dell screen for a second.
And we have the Dell screen. Let's go into the Bios. Almost five amps now, charging the battery and running the laptop at the same time. All right.
As adapters detected batteries at 25%. So unplug the charger and see if it stays on. Stays on okay. So that means that everything got fixed on this. So to recap, we weren't getting the main power rail to stay on.
I tried changing out the power management chip. That didn't fix it. We try changing out that first MOSFET, because the gate pin looked like it was shorted out, but it definitely was not the issue. And after another inspection of the board, which I missed on the first time around, whenever you inspect the board, you should be looking for these components that are that have fallen off or got ripped off the board.
But whenever the person had opened up the bottom and was trying to pry the bottom off the pride on the board and rip that component off, which is which was a crucial, component to actually start up the, the board. So, we got that changed out and now everything's working. Thanks for watching. See you next time.
2024-12-18