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

[kodox]

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

yes, PR603. it's a shunt resistor for VRAM power supply circuit and luckily it's not beep and displayed "1" in your multimeter like PL601, i assumed VRAM power supply is safe.

for PL601, PL602 & PL603 it's surprising not showing a value between 200-500 in your multimeter. i hope not the graphic chip make the shorts...

[fireaza]

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

OK, I'll try that tomorrow!

Also, just checking, when you said "PR603" you didn't mean "PL603", right? I just want to be sure I tested the right component! If it helps, PL601, PL602 & PL603 are all beeping with "1" when I check continuity to ground.

[kodox]

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

PL601 indicates short? hmmm....
can you remove PL601, PL602 & PL603?
after removed test the continuity to ground on left and right side (from the last photo on post #76) pin of PL601, which sides beeps?

[fireaza]

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

Got it! Also, you were right! I re-soldered PQ707, PQ701 & PL100 (and the two solder bridges nearby) and I was able to plug the AC adapter in without the LED turning off! Progress!

PL601 - Multimeter beeps and displays "1". Same thing happens on both the red and black probes as well as both sides of the component.

PR603 - With black probe on component and red on ground, it beeps for a moment then displays "432". Both sides of the component give the same reading. Putting the red probe on the component and the back probe on ground does nothing, it doesn't beep and continues displaying "1".

[kodox]

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

test it without removing it

[fireaza]

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

Hooray! Sounds like we're making progress!

PL601 being this component here?



Does it need to be removed from the board like PL100 in order to test it, or can it be tested without being removed?

[kodox]

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

*EDIT* Ah! I think I've found something! I removed the PJP600 solder bridge and now when I test continuity between PL100 and ground, I'm getting different results from before! With the black probe on PL100 and the red probe on ground, I get a short beep, follwoed by
"442". With the red probe on PL100 and the black probe on ground, I get a short beep, followed by some large numbers, before finally settling on "1". Trying the test again usually results in "1" right away, no beep.

you've found the shorts, if you place PQ707, PQ701 & PL100 and then you plug AC adapter, the LED won't turned off.

those shorts are in graphic chip & VRAM power supply area (page 63 on schematic), before you remove anything on this area check for continuity to ground on PL601, your multimeter will beep & show a number. then check PR603

[fireaza]

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

OK, I've cleaned up that mess on the back of the motherboard and cleaned up the messy solder on that chip.



From what I can see, it looks like whoever was trying to fix this board previously pulled one of the pads off the mainboard, since that brown part looks like bare silicon to me. Any idea where this pad would be connected to? It seems like the trace runs under the chip...

[fireaza]

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

Hmmm, where do you guys think I should go from here? I'm a bit concerned about that mess on the bottom of the motherboard. Is this likely to be a problem when it comes to fixing this motherboard? Or will I discover if it is or not after further diagnosis with kodox's solder bridge probing method or using a PSU like dellxps15 recommended?

it's round solder pads

OK then. So both round solder bridges need to be removed then?

*EDIT* Ah! I think I've found something! I removed the PJP600 solder bridge and now when I test continuity between PL100 and ground, I'm getting different results from before! With the black probe on PL100 and the red probe on ground, I get a short beep, follwoed by
"442". With the red probe on PL100 and the black probe on ground, I get a short beep, followed by some large numbers, before finally settling on "1". Trying the test again usually results in "1" right away, no beep.

[kodox]

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

Oh, I've been focusing on the wrong solder bridges? OK, I'm trying to find the bridges you mentioned. I've found PJP301 but I'm not sure which one it is! Would it be the rectangular solder pads to the left, or the round solder pads to the bottom?

it's round solder pads

[dellxps15]

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

problem: when inserting power supply, psu light turns off. means short on 19volt rail on motherboard.

solution:
1 find if short is on vin or B+ side.
if on B+ side, remove all pjp on the b+ side and after remove all of them, see if still shorted.
if still shorted could be some vin of pu component.

if short goen after all pjp removed, solder back one by one and see when short come again.
after u find shorted pjp, try removing capacitor 2 by 2 and see if short gone, then pu and soon till short is gone.


edit: yes that is a lab psu. but looks like that board got much work already done on it, looking like was already put in a oven.

when measuring for short, just put black of multimeter on a metal usb plate or metal plate on the board and with the red u probe always in diode mode.

[fireaza]

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

lots of work i see here. if u have a lab psu, u dont need to remove a single component of the pc as u have short on the 19volt rail. for safeti i would have just removed the gpu volt to not inject 19v in it if it was the cause of short. removing all those component is very stressfull. get a proper lab psu and ull find the bad component in a short of time without removing a single component.

Tell me about it! I'm starting to feel like I quicker solution would be nice! Would a PSU really be that quick and easy? Would one like this do?

http://amzn.asia/d/1nYcelN

It's ￥7,999 which isn't too bad when you consider that getting this laptop sent to a professional repair lab would cost around ￥26,000.

PJP304 & PJP305 is the same but that PJP's is not connected on B+ line (according to schematic), find & remove solder bridges on these PJP's:
- PJP203
- PJP301
- PJP600
- PJP303

Oh, I've been focusing on the wrong solder bridges? OK, I'm trying to find the bridges you mentioned. I've found PJP301 but I'm not sure which one it is! Would it be the rectangular solder pads to the left, or the round solder pads to the bottom?



Also, as I was searching for the other bridges you mentioned, I noticed that the bottom of the board doesn't look too good! I've never really noticed since I've been focusing on the top of the board! Here's some photos:


This solder bridge is one of the ones you listed and looks to be a really bad shape! Possible cause of my problem?


Here's another area of the board with some nasty-looking gunk! It also looks like there's a solder bridge between two legs of that component! That can't be good!

[kodox]

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

lots of work i see here. if u have a lab psu, u dont need to remove a single component of the pc as u have short on the 19volt rail. for safeti i would have just removed the gpu volt to not inject 19v in it if it was the cause of short. removing all those component is very stressfull. get a proper lab psu and ull find the bad component in a short of time without removing a single component.

fortunetelly he doesn't have one, but he's willing to buy only to fix this mainboard only. so i guide him step-by-step to find shorted components

[kodox]

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

PJP304 & PJP305 is the same but that PJP's is not connected on B+ line (according to schematic), find & remove solder bridges on these PJP's:
- PJP203
- PJP301
- PJP600
- PJP303

[dellxps15]

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

lots of work i see here. if u have a lab psu, u dont need to remove a single component of the pc as u have short on the 19volt rail. for safeti i would have just removed the gpu volt to not inject 19v in it if it was the cause of short. removing all those component is very stressfull. get a proper lab psu and ull find the bad component in a short of time without removing a single component.

[fireaza]

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

OK, here's my results:

PJP200 solder bridge removed = PL100 top pin still beeps
PJP300 solder bridge removed = PL100 top pin still beeps

Then there's PJP302... It's very strange, no matter how clean I get this bridge, there's still continuity across it! Here's a photo:



My guess is those two little solder blobs marked "PJP304" and "PJP305" are bridging the same thing that PJP302 is. But your instructions said to remove one bridge, test, then re-solder and try a different bridge if PL100 still beeps. So, I'm not sure if I should be doing this with PJP304, PJP305 and PJP302 or I should treating all 3 bridges like they're the same bridge..?

[kodox]

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

nope, just try to remove the easiest one.

after you sure 100% the solder removed from the PJP, test using the continuity to ground on PL100 top pin (on the last photo), if not beeped, you've found the block of circuit that causes shorts. if still beeped, reapply the solder on that PJP and move to the next PJP

[fireaza]

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

Oh, OK.

There's a few PJP solder bridges on this board, are there any particular ones you recommend trying first? For example, the closest one to the AC connector is PJP200, so would it be the best one to try? There's also a few PJP solder bridges that don't have any solder on them, so should these be ignored?

[kodox]

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

glad you've finally found proper tips to remove solder bridges, about the PJP you've remove the solder bridges on it & measured, actually it's not the PJP we should concern because those pjp it's not on B+ line (AC Adapter Line), we can ignore PJP100 & PJP102 for now and move to PJP's that i've mentioned before

[fireaza]

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

Ah, I thought that might have been why. That's a shame, I thought it might have been indicating the short had been removed!

OK, I've purchased a flat-sided soldering iron tip to see if I could cleanly remove the solder from the solder bridges. Well, I feel really dumb for having had so much trouble using solder wick in the past, because the flat-sided tip removed it all in seconds! This whole time I wasn't using the correct tip!

Anyway thanks to this new tip, it seems like I've completely removed the solder bridges. Checking continuity between each side of the bridge doesn't result in a beep, but some numbers do appear on the multimeter's screen. The number is in the 1000s, so I'd say that the bridge is gone. Here's a photo anyway:



Here's what I get when I check continuity between different sides of the solder bridges and ground. The "sides" are based on the orientation you can see in the above photo:
PJP100 (right side): 0
PJP100 (left side): 983

PJP102 (top side): 773
PJP102 (bottom side): 1561

It seems a bit suspicious to me that one of the solder bridges is showing "0" for the ground continuity test, what do you think?

When you said "test PL2 using continuity test to ground" is the "PL2" you're talking about "PL102"? I can't find any components labelled "PL2". If so, should I be testing with the component still soldered to the board, or removed, like PL101?