Repair hsb NM-45 NM-B451 (lenovo 330)

[Jeroentje]

Hello,

Due to the lockdown I try to learn more about basic repair things that's why I ask for a bit help.

I have a liquid damage laptop with one burned mark (no components), a oxidated component ( UL indicator ) and some little left overs (marked yellow)

I measure short, I have found boardview, a little complicated yet but that will come.
Can some help to identify the 6 dot places why could there be damage there ?
Is it gnd or vcc ?

So far nu burned components found, 20v come is and stops after first mosfet.
Around the cpu the mosfet mesure short.
Takes no A and noting is getting hot.

I hope finaly I can do a (lucky) repair.

BR

[Sephir0th]

Re: Repair hsb NM-45 NM-B451 (lenovo 330)

What is the exact behaviour of the Board and Where exactly did you injected and how much volts?

Check Resistance to ground right after Second mosfet or Current Resistor.

Low Ohms Reading around CPU are normal. Exact measurement there?

[Jeroentje]

Re: Repair hsb NM-45 NM-B451 (lenovo 330)

after first mosfet (pq311) 20v comes in and 0v out.
injecting is kind of new for me, I injected 7.4v on battery plus and pq314 gets warm.
after first resistor 0.7 ohm from ground

there are no lights or power consumption with adapter.

https://www.badcaps.net/forum/showthread.php?t=79393

[Sephir0th]

Re: Repair hsb NM-45 NM-B451 (lenovo 330)

So you mean 0.7 Ohms on Main Power Rail? If Yes, start injecting 1V, 0.5Amps there and Check whether Something getting hot. If nothing is getting hot, But Voltage Drops, Raise the amps in 0.5 steps and Check again Till you found Something getting warm/hot.

Sorry, but can't Take a Look to Boardview right now, because i'm online with phone

Best regards

[Jeroentje]

Re: Repair hsb NM-45 NM-B451 (lenovo 330)

thanks !

I have done it, it seems that the burned mark get's hot.
tested on both sides.

I have "cleaned" the hole further, it does not get hot any more but short is still there and no other components does get warmer. hmmmmm
maybe a weaker spot on multi layer pcb ?

I attached the burned place before cleaning.

[Sephir0th]

Re: Repair hsb NM-45 NM-B451 (lenovo 330)

Oh, i didn't noticed that the PCB is physically damaged Like this, before. Maybe Layers inside are shorted to each other, which shouldn't be. Don't know for Sure how to proceed now, because i hasn't to do a Job Like this so far.

Maybe there isn't everything lost right now, but from now on you need assistance from someone Else with more experience with this dort of damage.

Best regards

[Jeroentje]

Re: Repair hsb NM-45 NM-B451 (lenovo 330)

I did some more testing and the lane around the now hole get's warm.

I drilled a hole in the board with a sharp drill, in the hope it is not shorting anymore, IF it does shorts there, fact is temp is gettingpretty warm on that spot.

I still does not onderstand the boardview application. I like to know what line there is on the top and bottom from the hole, is it GND GND or VCC VCC or GND VCC. If I know wha is what then I can focus on that point or next one.

In the jpg I have top and bottom added and you can see the heat apperance on both sides with alchol.
Every time I investigate I hope to see look the short is gone !

thx

edit
I disconnected pj3501 , short same, less short at other side, but not completly gone. Attached photo

[Sametbey]

Re: Repair hsb NM-45 NM-B451 (lenovo 330)

You can see the leg connection points of the parts in the dashboard view. you cannot see the intermediate roads. Computer motherboards are arranged in 7 layers. and complex. There is likely to be connection under it when drilling holes on the board.

[Jeroentje]

Re: Repair hsb NM-45 NM-B451 (lenovo 330)

ok, 7 ok wow
drilling was after https://www.badcaps.net/forum/attach...6&d=1613250932 to have "lucky" shot

[Jeroentje]

Re: Repair hsb NM-45 NM-B451 (lenovo 330)

I removed the pcb short by a dremel, now there is a short a bit further, even the orginal charger (20v draw on 230 4 watts) can cause to heat up the LV5083A. I removed a cap around it with a other color but that did not the trick.

Is it likely that the chip is gone or can it still be a component around it ?

Picture:
green no short
red short (1.9 ohm)
red on chip heating parts
yellow on both sides resistance

[Jeroentje]

Re: Repair hsb NM-45 NM-B451 (lenovo 330)

removed red caps, not shorted, still 8 ohm
LV5083A removed still 8 a 9 ohm on the red places
thank god after putting the chip back it looks the same (not very experienced with it)

the board is only taking 1 watt at 20v not 4 watts
battery does not charge, no usb power available

I was really hoping that some component was heating up and did cause the mailfunction

any tips are welcome offcource
and otherwise nice diary here :P

[Jeroentje]

Re: Repair hsb NM-45 NM-B451 (lenovo 330)

case closed

[mtherana]

Re: Repair hsb NM-45 NM-B451 (lenovo 330)

What software you used for PCB in the picture if I may ask?

I did some more testing and the lane around the now hole get's warm.

I drilled a hole in the board with a sharp drill, in the hope it is not shorting anymore, IF it does shorts there, fact is temp is gettingpretty warm on that spot.

I still does not onderstand the boardview application. I like to know what line there is on the top and bottom from the hole, is it GND GND or VCC VCC or GND VCC. If I know wha is what then I can focus on that point or next one.

In the jpg I have top and bottom added and you can see the heat apperance on both sides with alchol.
Every time I investigate I hope to see look the short is gone !

thx

edit
I disconnected pj3501 , short same, less short at other side, but not completly gone. Attached photo

[Antonynl]

Re: Repair hsb NM-45 NM-B451 (lenovo 330)

case closed

Did you fix it in the end Jeroen?