DELL N5010 shorted area

[sparker1]

Hello, I have a Dell N5010 that has a shorted area on both sides of the board in the same (reciprocal) area. The section in the schematic belongs to the battery charger management. All the components in the two areas are shorted. I am not sure what is the best way to proceed. I was going to remove components one by one to see if the short disappears. I have already removed the buck controller (PU4501) as you can see in the picture but the short remains. I thought the next suspects would be the mosfets (PU4504/5/3) and my plan was to remove them one by one and test for the short at each removal. Is this what you guys would do? Any suggestions would be appreciated. I don't have an oscilloscope and wouldn't know how to use one anyway. I was going to bin the board and buy a new one but the costs are too much.

[khaahk]

Re: DELL N5010 shorted area

Short can be between 2 points, it is meaningless to say that area has short. Show points. Do not apply power without buck controller on board, it may damage the board...

[sparker1]

Re: DELL N5010 shorted area

But every component within the area is shorted to ground. They all get scorching hot.

[khaahk]

Re: DELL N5010 shorted area

So you got 0 ohms to gnd from all 3 points?

[sparker1]

Re: DELL N5010 shorted area

So you got 0 ohms to gnd from all 3 points?

Well, nearly 0.
At Point 1 =2 Caps (both read the same) = 0.3 ohms and 7.6 ohms at other end
At Point 2 =Cap = 0.3 and 2.9 ohms
At Point 3 =Mosfet:
pins1, 2 and 3 =7.6 ohms
pin 4=134.9 ohms
pins 5,6,7,8 =2.8 ohms

My DMM is set at the 200 ohm scale and shows 0.4 ohms when the probes are touched together.

Continuity meter gives a beep for everything in the area to ground. I was thinking there is a component within the circle(s) that is causing the entire circuit to show as shorted. My first guess was the buck converter but its removal didn't help. Appreciate your interest Khaahk. A palindrome!

[khaahk]

Re: DELL N5010 shorted area

Start removing the mosfets, starting with 4505, then 4504 and see how resistances change. I reapeat my suggestion: do not apply adapter power without buck controller, the situation may become worse. (if it hasn't already).

[sparker1]

Re: DELL N5010 shorted area

The mosfets were my next choice too. I won't apply power without the buck converter.

[sparker1]

Re: DELL N5010 shorted area

OK. I removed both mosfets and the short seems to have gone. Here are the measurements with the mosfets removed:

Point1 (2 caps) = 0.3 and infinity
Point 2 (cap) = 0.3 and infinity
Point 4 (mosfet) = pin4 is 0.207Mohm all other pins infinity.

I'll replace those two mosfets and the buck converter and see what happens.

[sparker1]

Re: DELL N5010 shorted area

No luck. The short circuit has gone and nothing gets hot but no sign of life. Something else is broken. There are no lights and no fan spin. Could it be a bios problem now?

[sparker1]

Re: DELL N5010 shorted area

Reprogrammed bios and no change-dead. I've spent enough time on this. I'll fork out for a working board.

[khaahk]

Re: DELL N5010 shorted area

No voltage measurements? Giving up a little too easy...
PU4502 voltages on all pins?
+3.3V_ALW_2 present?
+3.3V_ALW present?
+5V_ALW present?
Pin 2 and 22 voltage on PU4501?

[dj_ricoh]

Re: DELL N5010 shorted area

No voltage measurements? Giving up a little too easy...
PU4502 voltages on all pins?
+3.3V_ALW_2 present?
+3.3V_ALW present?
+5V_ALW present?
Pin 2 and 22 voltage on PU4501?

PHASE 2 3.3v_alw and PHASE 1 5V_Pwr its the input right?

VREG 3 and 5 its the output on PU4601

P.S. Don`t forget ACOK on pin 13 ; That could be a give away if its not ok there

[razu]

Re: DELL N5010 shorted area

Open the battery charging Ic BQ 24745 Pu 4501, and then u measure short area If short is gone the Ic is faulty If not gone the short is probably a PF (capacitor) Beneth the chips
Have a good luck!!!!!!!!!!! Friend

[smali]

Re: DELL N5010 shorted area

it is very difficult to point out the short component on main power line because a lot of component are mount on that line and every will be show short so a simple way which i used to inject external power low voltage with high ampere so the short component will be burn or heat up so it is simple way which i rectify many laptop.

[SteveNielsen]

Re: DELL N5010 shorted area

OK. I removed both mosfets and the short seems to have gone. Here are the measurements with the mosfets removed:

Point1 (2 caps) = 0.3 and infinity
Point 2 (cap) = 0.3 and infinity
Point 4 (mosfet) = pin4 is 0.207Mohm all other pins infinity.

I'll replace those two mosfets and the buck converter and see what happens.

By replace do you mean with new parts or putting back the originals? Did you test the MOSFETs while you had them out of circuit?

[sparker1]

Re: DELL N5010 shorted area

The buck controller was replaced with a new one. The old mosfets were shorted drain to source and were replaced with a stock I had - some were new and some off scrap boards so I'm not sure how old they were but they tested OK. I did some voltage measurement on PU4601 (buck controller) voltages:
Pin 23 (pwgood)=2.59v
Pin 17 (5v)=3.27v
Pin 8 (3v)=0.0v
I don't know what to make of these readings.

[dj_ricoh]

Re: DELL N5010 shorted area

The buck controller was replaced with a new one. The old mosfets were shorted drain to source and were replaced with a stock I had - some were new and some off scrap boards so I'm not sure how old they were but they tested OK. I did some voltage measurement on PU4601 (buck controller) voltages:
Pin 23 (pwgood)=2.59v
Pin 17 (5v)=3.27v
Pin 8 (3v)=0.0v
I don't know what to make of these readings.

read the rest .
take every pin!