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

if i may share my experience here, finding shorted mosfet on the circuit is somehow a bit tricky. my method when using a multimeter, using continuity test then probe the electrolyte condensator after the choke (usually marked PLxx on mainboard), when probing those electroyte condensator is beeping, pay attention to value showed on multimeter (i use digital one), if the value less then 0.15 its 70% mosfet shorted to make sure 100% the mosfet is shorted, unsolder the PLxx, measure the mosfet side with ground and it should be beeping & the value less then 0.9 if the mosfet is the cause of shorted

[fireaza]

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

There's a few components marked "PL-something" on this board. The ones with only 1 digit (i.e "PL4") are small components, while the ones with 3 digits (i.e "PL700") are large components, so I'm assuming the large ones are the ones you're talking about?

In that case, here's the ones I found and what they display on the multimeter when probed:
PL700 = "-008"
PL701 = "-008"
Pl100 = "-002"
PL102 = "-002"
PL101 = "-002"

Is any of these helpful? Keep in mind, I still have the two mosfets and two solder bridges from before de-soldered!

[kodox]

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

There's a few components marked "PL-something" on this board. The ones with only 1 digit (i.e "PL4") are small components, while the ones with 3 digits (i.e "PL700") are large components, so I'm assuming the large ones are the ones you're talking about?

In that case, here's the ones I found and what they display on the multimeter when probed:
PL700 = "-008"
PL701 = "-008"
Pl100 = "-002"
PL102 = "-002"
PL101 = "-002"

Is any of these helpful? Keep in mind, I still have the two mosfets and two solder bridges from before de-soldered!

are you probed it with one lead of the multimeter to ground or both of the leads to the those inductor (PLxx)? i assumed you probed it with both lead of the multimeter to those inductor, because the value is very low.

measure again with one lead of the multimeter connected to ground and the other to inductor

[fireaza]

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

Oh, OK. In that case, here's those components from before but with one probe on ground:

PL700 = "477"
PL701 = "002" (also makes a beep sound)
PL100 = "002" (also makes a beep sound)
PL102 = "489"
PL101 = "484"

Does this help? Some of the components are behaving differently so I'm hoping this means we're on the right track! As before, I still have those two mosfets and solder bridges removed, so this might be expected behavior for when these components are missing!

[kodox]

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

PL100 & PL701 is too low, you had multiple shorts in this case, try remove PL100 fisrt. after it's removed, measure using continuity test again with one lead to the ground and the other lead to PL100 pin 1 and after that to pin 2 of PL100 which one is the lowest value & beeped? if the lowest value on the pin that connected to mosfet, replace those mosfet. if the lowest value not on the mosfet side you should see the schematic to find what the load is, but i'm hoping not the load that make the short.

[fireaza]

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

OK, it sounds like we're getting somewhere! Should I re-solder the two mosfets and the two solder bridges before I remove and test PL100? I've left these removed just in case, but it sounds like they will need to be in place based on what you said.

[kodox]

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

it's okay, don't put back them for now. focus on those inductor that you've probed & beeped...

[fireaza]

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

OK, PL100 has been removed! I accidentally dropped it onto my workbench, and since it was hot, it now has some of the rubber sheet from my workbench melted to it :/

Now for testing, I'm not sure how you tell which pad is 1 and which is 2. One of the pads has 3 short lines coming from it, so I think this indicates something, so this is what I'll be using here!

OK, here's what's happening when I test the solder pads where PL100 was with the probes of my multimeter connected to ground.

Solder Pad "1" (the one without the three short lines coming from it): Beeps, shows "002" on multimeter.
Solder Pad "2" (the one with the three short lines coming from it): Doesn't beep, shows "566" on multimeter.

Checking continuity from the beeping solder pad to the two mosfets' solder pads, I'm getting beeps for both mosfets, so it seems like this solder pad is connected to the mosfets. So based on what you said, the two mosfets are bad? We tested them before, and it seemed like they were fine..?

If it helps, here's what the laptop's mainboard is looking like now:

[kodox]

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

actually, there's no pin 1 or 2 on inductor
just said it to make easier to understand, look's like PL100 & PL701 connected directly? which pin on PL100 make the beep on multimeter? left side (from the picture) near PL701 or right side near PL101 & PL102?

[fireaza]

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

Oh, I see!

I think PL100 & PL701 are connected, as I get a beep on my multimeter when I do a continuity test between the left pin (in the photo) of PL100 and PL701. Probing the right pin of PL100 doesn't get a beep though, just "500" on the multimeter.

The pin on the left of the photo is the one that beeps! Does this reveal anything useful?

[kodox]

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

is PL701 connected directly to DC_IN socket or is there other components that had connected on same line as PL100 & PL701? Can you plug-in the dc socket then measure in continuity test on the socket where the adaptor is plugged?

do u have s schematic for this?

[fireaza]

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

OK, I've plugged the AC socket back in and run a continuity test from the AC socket to PL701 and then to PL100. There is continuity to PL701 and also the left pin of PL100 (the one that beeps when grounded) but not the right pin. I don't have any schematics for this laptop unfortunately!

Anything useful here? Are we starting to get the cause of my problem narrowed down?

[kodox]

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

i mean test in dc socket (where the adapter connected) for continuity after pluging in it to mainboard, is it beeped or not? if beeped i think the shorts in the "dc in" area, it's a main gate for 19v to enter the system, after testing it (whatever the result is) try to lift PL1 & PL3 but don't remove it, just lift one leg of PL1 & PL3 then try to connect AC Adapter and see if it's off or not, if it off remove the AC adapter immediately, if it not, you've been narrowed the shorts then

can you see something like LA-xxxx or DA0xxxxxx printed on the board?

[fireaza]

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

i mean test in dc socket (where the adapter connected) for continuity after pluging in it to mainboard, is it beeped or not? if beeped i think the shorts in the "dc in" area, it's a main gate for 19v to enter the system

I didn't do it right? Here's a photo of how I tested it:

can you see something like LA-xxxx or DA0xxxxxx printed on the board?

Yeah, near the CPU it has "AAP20 LA-B753P" printed.

[kodox]

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

no, it's not your fault. my mistake can't explain what i meant, but what you've doing it's okay. now, just move the black probe to ground, i hope it's beeped...

i'll search the schematic now, so we can had better understand what's going on and where...

[fireaza]

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

Yep, my multimeter beeps when I test continuity between the AC socket and ground on the motherboard!

OK, let me know if you find anything!

[kodox]

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

It's here, the schematics https://www.badcaps.net/forum/showthread.php?t=69089 post #18

[fireaza]

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

Cool! But uh, I really don't know what to make of it, it might as well be in Chinese! Is there anything you can get out of it?

[kodox]

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

look for B+ only (with bold letter) on schematics, thats where your shorts is! luckily, there's a jumper called PJPxxxx on every "B+" on this board. remove the solder bridges using wick until it's completely clean from lead but, only when it's connected to B+ only.

after removing the solder bridges on one PJPxxxx, test using the continuity to ground until your multimeter not beeps anymore. if all the PJP connected to B+ removed and your multimeter still beeps, 70% your shorts caused by small smd capacitor connected to B+ line.

after what you've done on measuring, the components on right side of PL100 (page 60 on schematics) is not the cause of shorts.

try to test PL2 using continuity test to ground, is it beeped? if not, you can ignore it for now and back to removing solder bridges on PJPxxxx.

[fireaza]

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

From what I can see, there's 2 "PJPxxxx" solder bridges in the power area of this board, PJP102 and PJP100. I've already tried to remove these solder bridges previously, but I didn't get all the solder. I'll try again with a flatter iron tip and see if I can get them cleaned. There's also a few other "PJPxxxx" solder bridges on this board, but they're far from the power area, so they're not what I need, right?

Also, I thought I'd try plugging in my AC adapter to see what happens now that I have a few components removed. To my surprise, the LED on the AC adapter doesn't turn off now! Does this indicate we've possibly found where the short is? Or is this expected behavior for when the components I've removed aren't there?