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Old 01-20-2022, 01:43 AM   #1
samstown
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Default Acer - N19C2 - MB EH7LW - Sudden death

Hello, I got an Acer N19C2 that doesn't show sign of life. It was working properly and died while I was typing. No charging LED.. nothing, so I opened it and I found schematics on this forum,

https://www.badcaps.net/forum/showth...ighlight=EH7LW

which is awesome.

Using my multimeter, I can see 19V on PQB3 but not on PQB4. Does that mean for sure that this Mosfet PQB3 is the problem ?

Thanks
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Old 01-20-2022, 04:33 AM   #2
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Default Re: Acer - N19C2 - MB EH7LW - Sudden death

https://badcaps.net/forum/showthread.php?t=90356
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Old 01-20-2022, 05:01 AM   #3
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Default Re: Acer - N19C2 - MB EH7LW - Sudden death

Thank you. Are you the same Piernov as Rossman forum ?
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Old 01-20-2022, 05:16 AM   #4
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Default Re: Acer - N19C2 - MB EH7LW - Sudden death

So I have HBP. PRB3 is short to GND. I will try to remove it
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Old 01-20-2022, 01:46 PM   #5
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Default Re: Acer - N19C2 - MB EH7LW - Sudden death

so I removed PRB3, that's a resistor ? Can I just short it to test?
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Old 01-21-2022, 05:00 AM   #6
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Default Re: Acer - N19C2 - MB EH7LW - Sudden death

Am I missing something. It doesn't work. Before I create more problem.
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Old 01-21-2022, 06:47 AM   #7
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Default Re: Acer - N19C2 - MB EH7LW - Sudden death

https://www.badcaps.net/forum/showpo...50&postcount=2
Quote:
2.1.2. Short to ground on main power rail
Most common issue in this case is a short to ground on main power rail caused by a capacitor, and IC, a MOSFET…
In this case you have to measure *exact* resistance to ground on the main power rail (same point as previously). If it is lower than several kohms there's a short to ground.
As indicated in the "Begginer's guidelines: what not to do" section, DO NOT inject 19V. Check high-side MOSFETs for short, easiest way is to place one probe on the main power rail and the other probe on each large inductor of the board. If one is lower than 1 ohm, there's a possibility of high-side MOSFET short. If not, you can start injecting voltage *at 1V*, and double check none of the large BGA is warming up. If 1V is not enough, you can start increasing voltage, after making sure none of the large BGA is warming up again.
Once you find the bad component, remove it, confirm short to ground is gone, and replaced it. Don't apply power to the board if the component is removed without being sure that it'll not cause any harm.
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Old 01-25-2022, 01:17 PM   #8
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Default Re: Acer - N19C2 - MB EH7LW - Sudden death

ok, I don't get anything after Mosfet PQB3. Power rail is not shorted. So I'll remove this PQB3
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Old 01-25-2022, 01:22 PM   #9
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Default Re: Acer - N19C2 - MB EH7LW - Sudden death

PQB3 could be defective or PQB3 may not be enabled with the proper voltage on the gate.

Every mosfet has 3 pins - SOURCE; DRAIN and GATE. Often, to allow for heavy currents through the mosfet (effectively a solid-state relay) - the designers will gang up or group the pins together so they can share the burden.

Remove all power / no battery.

Check if the mosfet is shorted:

Meter in resistance mode (2k is ok).

Check the resistance between -

SOURCE & DRAIN
SOURCE & GATE
GATE & DRAIN

Post the values.

Share the markings on the first mosfet but most likely the details of the pinout are:

1-2-3 = SOURCE
4 = DRAIN
5-6-7-8 = DRAIN

You can see the shorts on the PCB layout = copper plane with green solder mask.
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Old 01-25-2022, 01:39 PM   #10
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Default Re: Acer - N19C2 - MB EH7LW - Sudden death

Thank you mon2 for you reply, I really appreciate it. Looking at PCB copper, what you describe looks like what I get.

IC = B04N03JL00902 (or somthing near...)
https://datasheetspdf.com/pdf-file/1...OS/EMB04N03H/1

1 to 2 = 0 ohm
2 to 3 = 0 ohm
1 to 3 = 0 ohm
123(source) to 4 (Gate) = 0.589 (black probe on 4)
4 (gate) to 5678 (Drain) = open (tried probe on both side)
123 to 5678 = 0.475 (black probe on 5678)

Thanks
Sam
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File Type: jpg WhatsApp Image 2022-01-25 at 20.36.38.jpg (286.5 KB, 3 views)

Last edited by samstown; 01-25-2022 at 01:43 PM..
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Old 01-25-2022, 01:44 PM   #11
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Default Re: Acer - N19C2 - MB EH7LW - Sudden death

The resistance checks look ok and the mosfet does not appear to be shorted.

Place the meter in DC volts mode (use 30V or higher).

Carefully, check the voltage on Pin #1 of this mosfet = should match the DC adapter input voltage.

Then, carefully check the GATE voltage. Most likely the voltage on the GATE is not high enough to enable the pass through voltage from SOURCE & DRAIN pins.

Post the readings.
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Old 01-25-2022, 01:49 PM   #12
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Default Re: Acer - N19C2 - MB EH7LW - Sudden death

Thanks.

PIN 1,2,3,4 = 0V
PIN 5,6,7,8 = 19.45
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Old 01-25-2022, 01:49 PM   #13
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Default Re: Acer - N19C2 - MB EH7LW - Sudden death

Quote:
Originally Posted by samstown View Post
So I have HBP. PRB3 is short to GND. I will try to remove it
Quote:
Originally Posted by samstown View Post
ok, I don't get anything after Mosfet PQB3. Power rail is not shorted. So I'll remove this PQB3
???
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Old 01-25-2022, 02:11 PM   #14
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Default Re: Acer - N19C2 - MB EH7LW - Sudden death

PQB4 excelliance B12N03E looks ok, no short between source, drain and gate

Last edited by samstown; 01-25-2022 at 02:15 PM..
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Old 01-25-2022, 02:42 PM   #15
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Default Re: Acer - N19C2 - MB EH7LW - Sudden death

as I get no Volt on PQB3 and PQB4 source, it must be the two caps... but they are not shorted and just to add, nothing get hot
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Old 01-25-2022, 02:46 PM   #16
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Default Re: Acer - N19C2 - MB EH7LW - Sudden death

Posting the partial parts of the schematic.

It will be a good idea to know the voltages on each pin on the charger IC @ PUB1.

Remove the battery but attach the official charger. Then carefully check the voltages on the charger IC. Post the readings.
Attached Images
File Type: jpg acer1.jpg (390.6 KB, 11 views)
File Type: jpg acer2.jpg (345.8 KB, 6 views)
File Type: jpg acer3.jpg (211.8 KB, 5 views)
File Type: jpg acer4.jpg (334.3 KB, 5 views)
File Type: jpg acer5.jpg (284.2 KB, 5 views)
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Old 01-25-2022, 03:23 PM   #17
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Default Re: Acer - N19C2 - MB EH7LW - Sudden death

Thank you for your help and patience.

Pin not listed = 0

5 = 2.64
9 = 0.30
16 = 0.4
17 = 0.24
19 = 0.24
20 = 0.24
24 = 1.8
25 = 1.03
26 = 0.24
27 = 0.24
28 = 18.86
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Old 01-25-2022, 04:22 PM   #18
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Default Re: Acer - N19C2 - MB EH7LW - Sudden death

See attached.

Can you confirm again that ACDET = 0 volts ?

This is a simple resistor based voltage divider.

Pin # 1 of PRB11 should be the same as the DC adapter voltage.

What is the reading ?

Then the junction between pin # 2 of PRB11 & pin # 1 of PRB13 should be a much lower but safe value for the charger IC to determine if the charger is plugged in or not.

What is the voltage reading between these 2 resistors ?

The voltage should be a value > 0v unless PRB11 is damaged or is missing from the logic board.
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File Type: jpg acdet.jpg (173.0 KB, 7 views)
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Old 01-26-2022, 03:36 AM   #19
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Default Re: Acer - N19C2 - MB EH7LW - Sudden death

Hello,

Sorry, my mistake was too late... Pin 5 = 0.

ACDET pin 6 = 2.64
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Old 01-27-2022, 12:53 PM   #20
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Default Re: Acer - N19C2 - MB EH7LW - Sudden death

Hello, ACDET = 2.64V, is this a good thing ?
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