Laptop's AC adapter turns off when connected, corrosion on power-related components

[fireaza]

Re: Laptop's AC adapter turns off when connected, corrosion on power-related componen

Thanks for the reply! It had been awhile since the last one, so I figured everyone was out of ideas! However, I've decided to sent the laptop into the repair lab. Since we know there's some kind of problem with the GPU, which is something a bit beyond the abilities of home repair.

Anyway, within hours of receiving the laptop, they've tested it and discovered the following symptoms:

• Scratches on the mainboard.
• Missing screws (I also discovered this when I went to re-assemble it!).
• Scratches on the case (there's a really big one that's hard to miss!).
• Does not power on.
• Dirty motherboard

And here's their diagnosis:

• Damaged capacitors
• Broken keyboard backlight port (I noticed this too!)
• Breakdown of the GPU (you guys called it!)

And here's the list of repairs the motherboard needs:

• Repair of the GPU
• Multiple capacitor replacement
• Keyboard backlight cable port replacement (I'm glad this can be fixed!)
• Thermal grease replacement (though I might re-do this myself, since I don't know if they will be using my preferred brand)
• Motherboard cleaning (I'm glad they're going to do this, the motherboard was really dirty and I wasn't sure how I would clean it!)

All up, it's going to cost around ￥32,800. Which isn't too bad, since that means all up, it's only cost me around ￥60,000 for a top-end Alienware 15, which usually go for over ￥100,000! And the stores sell used ones for over ¥ 300,000!

Anyway, thanks for all your help with the repairs guys! It's a shame we weren't able to fix it, but we came close!

[dellxps15]

Re: Laptop's AC adapter turns off when connected, corrosion on power-related componen

check resistor near cpu power ic, as 1.4 volt output is too much i think.

[fireaza]

Re: Laptop's AC adapter turns off when connected, corrosion on power-related componen

OK, I've removed pjp302 pjp304 pjp305, but I still get 7 beeps when I try to boot.

[dellxps15]

Re: Laptop's AC adapter turns off when connected, corrosion on power-related componen

yes remove those pjp 302 304 305 and see if notebook works.

[fireaza]

Re: Laptop's AC adapter turns off when connected, corrosion on power-related componen

Not PJP601, PJP600. After I removed this solder bridge, (and also cleaned up the solder mess on UH3 and re-soldered the components I had removed before) the LED on the AC adapter stayed on when it was plugged in.

*EDIT* (I didn't see you had edited your post!) I've found pjp302 pjp304 pjp305, but are these correct solder bridge to remove if my problem solder bridge was PJP600 and not PJP601?

[dellxps15]

Re: Laptop's AC adapter turns off when connected, corrosion on power-related componen

im reading again the discussion. so the problem making psu to turn off was pl601 ?



edit: remove pjp302 pjp304 pjp305 and power on pc again.

[fireaza]

Re: Laptop's AC adapter turns off when connected, corrosion on power-related componen

Sounds like it's important!

OK, I've here's the voltages:
UH3: 3.28v (on pin 1 & 5, nothing on the other pins) (multimeter set to 20v)

The next components are bit tricky, since they're under the heatsink and only one solder point of each component is exposed. Also, I can only see the label for PL502, the labels for PL503 and PL504 are covered by the heatsink! But from what I can recall, PL503 and PL504 are the two SMT power inductors next to PL502. Anyway, here's the voltages:
PL502: 1.572 (multimeter set to 2v)
PL503?: 1.591 (multimeter set to 2v)
PL504?: 1.448 (multimeter set to 2v)


As for PU500 and PU501, I'm having trouble finding them! I've found the label for PU500, but there's a bunch of different components nearby:


Is the nearby chip PU500?

Oh and if case it helps, I touched the heatsink and the areas around the CPU and GPU were warm, so it looks like they're getting power.

[dellxps15]

Re: Laptop's AC adapter turns off when connected, corrosion on power-related componen

uh3 is PLT_RST so is needed for good working.


with powered pc on, check uh3 voltages, pl502 pl503 pl504 voltages.also check pu500 pu501 pins voltages. always be carefull when checking.

[fireaza]

Re: Laptop's AC adapter turns off when connected, corrosion on power-related componen

This is apparently the schematics for my board:

https://www.badcaps.net/forum/attach...0&d=1524883267

[dellxps15]

Re: Laptop's AC adapter turns off when connected, corrosion on power-related componen

where can we find the schematics ?

[fireaza]

Re: Laptop's AC adapter turns off when connected, corrosion on power-related componen

Ah, I see. Would it be the GPU or CPU? If it's the GPU, that would line up with what was said before about there probably being a problem in the graphics area of the board.

Is the vcore something we've already tested in this motherboard? It sounds familiar. If not, after we've finished testing, would fixing the problem be a simple matter of replacing a dead capacitor, MOSFET etc or are are looking at something more complicated, like a BGA?

Oh, and before I forget, there's still the lifted solder pad problem with UH3:


I'm going to take a wild guess and assume that this will need to be fixed at some point!

[mcplslg123]

Re: Laptop's AC adapter turns off when connected, corrosion on power-related componen

7 beeps in dell doesnt mean ram failure-it means processor failure. So you need to check vcore circuit.

[fireaza]

Re: Laptop's AC adapter turns off when connected, corrosion on power-related componen

I fully re-assembled the laptop and tried plugging it in and turning it on. The laptop lights up! It doesn't boot though, and nothing appears on screen, it just beeps 7 times. Google seems to indicate that 7 beeps means a RAM problem, so I've tried swapping which DIMM the RAM is installed in and even booting with no RAM, but it still beeps 7 times.

THIS GUIDE suggests clearing the CMOS, but that didn't help.

[dellxps15]

Re: Laptop's AC adapter turns off when connected, corrosion on power-related componen

dunno that model in particular, but on my old m17x r4, all light were on the plastic covering the top case, the one that cover the keyboard screws and so on with the hole for the alienware power botton.
alienware power botton got just some hdd light in it, while that plastic got all other lights.

[fireaza]

Re: Laptop's AC adapter turns off when connected, corrosion on power-related componen

OK, I soldered those SMT power inductors back and did a partial assembly, by plugging the AC adapter and battery back in. I plugged in the AC adapter, and while it LED didn't go out, there didn't seem to be any sign that the battery was being charged (i.e the AC adapter or battery didn't get warm). Apparently with this laptop, the charging indicator is the power button on the keyboard, so I plugged in the keyboard too, but the power button didn't light up.

Does the entire laptop need to be reassembled before it will charge or something? Or is there some other problem?

[fireaza]

Re: Laptop's AC adapter turns off when connected, corrosion on power-related componen

Ah, so you're saying if we can get the laptop to switch to integrated GPU, and it start up, then the short is with the discrete GPU? Is the "PJP" point you mentioned the "PJP600" solder bridge we removed before? How about the ripped solder pad on that chip I showed you before? The laptop won't boot with that not fixed, will it?

Yes, I mentioned this before, but after re-soldering the components we removed (MOSFETs etc) and those two solder bridges, I connected the AC adapter and the LED light on the AC adapter stays on!

[dellxps15]

Re: Laptop's AC adapter turns off when connected, corrosion on power-related componen

i dont have the schematics, but i think that if u desolder the pjp point where it gives the 1.5 volt for vram, it will disable the discrete vga and work with just the integrated one. in addition as i have said before, board was previously put in a oven, so dunno what else could be bad now .....

to see if a short is gone, put psu again and if light stay on then short is gone.

[fireaza]

Re: Laptop's AC adapter turns off when connected, corrosion on power-related componen

Sorry, I thought I explained it clearly!

Oh, I thought the fact that the different probes give different results was useful, so I thought I'd tell you which happens with different probes.

Hmmmm, if the short is in the graphics chip area, does that mean the short is probably in the GPU itself? That's probably not something someone with a soldering iron can fix, is it? Where do you think we should go from here? Should I give up and leave this to a professional electronics repair lab? Or do you think it's worthwhile to try removing PC966, PC967, PC969 & PC970 then test again using continuity to ground on PL601?

[kodox]

Re: Laptop's AC adapter turns off when connected, corrosion on power-related componen

OK, I've removed PL601, PL602 & PL603!

Though, I accidentally confused PL601, PL602 & PL603 with PL501, PL502 & PL503 and removed them first! From what I've read, these components are "SMT power inductor" and have no polarity, so you can solder them in any direction. I've re-soldered PL501, PL502 & PL503, so hopefully there's no problems!

yes, inductor have no polarity. so you can solder it in anyway.

Anyway, here's the readings I'm getting:
PL601 right solder pad (as in previous photo) - beep and "-001". Both colored probes get the same result.

PL601 left solder pad (as in previous photo) - no beep and "78" with the black probe on the solder pad and red probe on ground. No beep and "472" with the red probe on solder pad and black probe on ground.

i've got confused with this, oh wait....
i had to read over and over to understand what you meant

you always should place black probe on ground and i think the shorts in graphic chip area, thats bad...
but, if you want to try more, you can remove smd capacitor near the graphic chip. it's in page 66 on schematic, but you can try to remove PC966, PC967, PC969 & PC970 then test again using continuity to ground on PL601 right solder pad

[fireaza]

Re: Laptop's AC adapter turns off when connected, corrosion on power-related componen

OK, I've removed PL601, PL602 & PL603!

Though, I accidentally confused PL601, PL602 & PL603 with PL501, PL502 & PL503 and removed them first! From what I've read, these components are "SMT power inductor" and have no polarity, so you can solder them in any direction. I've re-soldered PL501, PL502 & PL503, so hopefully there's no problems!

Anyway, here's the readings I'm getting:
PL601 right solder pad (as in previous photo) - beep and "-001". Both colored probes get the same result.

PL601 left solder pad (as in previous photo) - no beep and "78" with the black probe on the solder pad and red probe on ground. No beep and "472" with the red probe on solder pad and black probe on ground.