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ACER ES1 520 Laptop With No Display Fixed

By Jestine Yong on September 22, 2020

Received the laptop with no power problem.

Symptom: when pressing the power switch power led indicator light up for the moment and goes OFF.

First of all checked the Voltages of laptop Charger found 20V i.e. OK. Normally for testing we have to segregate the suspected area like we have to replace the Battery and power “ON” the Unit only on charger if it works then problem related to battery and respected Circuit on the motherboard & if laptop is powering ON using Battery then problem is with Charger adaptor and respected circuit on Motherboard.

Here it gives problem both the way so for further inspection I have disassembled the laptop.

And removed Motherboard for visual Inspection …..Didn’t found and physical damage or Burnt out.

Removed the DC IN cable from the motherboard power socket and Checked for 20V on cable Connector found OK i.e. charger and connectors are ok. Now connected cable on the motherboard connector and tested Voltages on the Main MosFet.

Drain = 19V

Source= 0V

Gate =0V

Here on Drain we are getting 19V because it is Always ON Voltage it will present on all power section on motherboard when you power the laptop either from the charger or from Battery. As this is N-channel MosFet it gets triggered when Gate receiving signal/Voltage (18 to 20V) and you get output from the Source of the MosFet.

But here Gate showing 0 Voltage that mean it is not triggering and giving O/P Voltages in further section for work.

In normal working when you press the power switch Super I/O chip receive the signal of DC in and by confirming the input signal it release signal O/P to MosFet driver circuit in various sections. Till all the sections having always ON Voltage in all the section but they will not come in process till get the order/Signal from the Super I/O.

So now we have to trace from where this MosFet is getting Gate Trigger Voltage.

If you have schematic of motherboard you can easily trace the circuit. If you have some basic tracing skill you can find it using Multimeter Beep mode on cold testing.

(When Motherboard is powered “OFF”). Put one probe on Gate Pin of the MosFet. And by other probe you can touch surrounding components where you get the Beep.

Note: in laptop you can never imagine which section component is located which side of the motherboard.

Some time you get Main MosFet on one side of the board and supporting MosFet on other (Backside) of the Board. Even I found same Model and same series of motherboard some time not matching the component location.

So I have downloaded the schematic diagram and by tracing I found that the Main MosFet driver IC is located on back side of the Motherboard near Battery charging section.

I have checked the voltages on surrounding component but not getting any Voltage. I have checked Surrounding components for short circuit but everything seems ok on this side. Now I have turned the board and start fault finding on Battery section Circuit.

Testing in Battery Charging connector surrounding components I found One SMD Capacitor showing shorting with ground.

Hence I removed the capacitor for confirmation

I have made SMD Holder for holding tiny SMD parts while testing.because many time part get skipped while testing and finding it is another big job.

On testing this capacitor Outside the Circuit it is confirmed that Capacitor is short.

But I am not having the same capacitor for replacement and there is no marking on board for resistor and on other tiny components so it is difficult to identify the component from circuit diagram to physical location on the board.

As per technical scenario this capacitor is connected with the ground hence I taken the chance to test the laptop without capacitor.

Hence I have reassembled the laptop and powered on………I got the display

In this Pandemic covide19 lockdown when all the markets are closed in our state hence I have not in possession to arrange the capacitor form my techno friends and customer need this laptop urgently. (Also In hurry I have not taken some Voltage testing photographs) by convincing to the customer fact about the problematic component which is removed from the PCB .He is agree to collect it in same condition. I have kept this laptop on burn-in test for one day it worked without any problem and customer took it a day after.

This article was prepared for you by Yogesh Panchal who works as a Computer Hardware Engineer in Mumbai India.

P.S- Do you know of any your friends who would benefit from this content that you are reading now? If so, forward this website to your friends or you can invite your friends to subscribe to my newsletter for free in this Link.

Note: You can check his previous repair articles in the link below:

https://jestineyong.com/hp-laptop-with-disk-0-error-fixed/

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19 Comments

Albert van Bemmelen

September 22, 2020 at 6:30 pm

Nice article with very useful made it yourself smd component holder!
For SOT23 smd transistors I have the PEAK Atlas 3 pin component holder but it was not cheap but makes quick testing of smd transistors a breeze. https://www.peakelec.co.uk/acatalog/pca23-peak-component-adapter-sot23.html

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- Yogesh Panchal
  
  September 24, 2020 at 6:15 pm
  
  Albeart,
  
  SMD Holder is Best out of waste Product Free of Cost to me LOL........
  
  Thanks! for sharing the link...
  
  I am always in favor when somebody afford to invest in some good professional tools in our repair Business it always payback.
  
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moshe

September 22, 2020 at 8:17 pm

That SMD fixture is very neat!!
thanks for sharing this.

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- Yogesh Panchal
  
  September 24, 2020 at 6:28 pm
  
  Thank you! Moshe
  As i repeatedly talking in comments invest in good tool make our effort valuable in terms of time consuming and success in work.
  
  You can see this guy how cleverly he is doing Micro soldering Works.
  I am not doing anybody's advertising here but we can learn the skill and way to give effort in proper direction for saving time and Neat work.
  Find a You tube Link.....................
  
  https://www.youtube.com/watch?v=hvpUmai7qlA
  
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mark kalembelembe

September 22, 2020 at 9:05 pm

Informative write up. As a matter of interest, why did you make the end of the spring wire needle sharp? Will certainly make one for myself since I experience similar problems.

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- Yogesh Panchal
  
  September 24, 2020 at 6:47 pm
  
  Mark,
  Thanks! for the Comment...
  as you now how tiny SMD Parts are.... say example of Capacitor they have silver shiny edge on left and right and in between brown material when you hold the capacitor from middle brown part chances are high to get it touch the shiny edge which are conductive material and you may get the Misguided reading while testing. hence by not using flatten point of the spring wire i have grind it in sharp needle tip. so that by help of rubber base component will not move /skip or shake while holding with the sharp tip...
  
  like law of center of gravity effect on the stability of an object at which weight is evenly dispersed and all sides are in balance.
  
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Humberto

September 23, 2020 at 6:41 am

Hi Yogesh, I´ve really found very interesting your article, so I re-read again. Very practical your SMD Component Holder, I´m thinking on built one. By the way, could you facilitate me the link(s) to download the Schematic Diagrams? If Yes, could you send it to me by means of Yestine Yong? He knows my e-mail address. Have a good day.

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- Yogesh Panchal
  
  September 24, 2020 at 6:49 pm
  
  Humberto,
  
  Thanks! for the Comment and your requirement is on the way.
  
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  - Humberto
    
    September 25, 2020 at 12:33 am
    
    Thanks, I´ve already received it. Thanks to Mr. Jestine Yong too.,
    
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- Som Shankar Kalihari
  
  September 25, 2020 at 7:33 pm
  
  Hello , dear
  This is good effort for testing of damaged smd capacitor, it is really good & with shaving of valueble time. Thanks. From Som Shankar Kalihari from Raipur (Chattisgarh) india.
  
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Parasuraman S

September 23, 2020 at 10:54 am

Excellent article with a lot of tips! I normally solder one end of the SMD components with a cut lead of any component. Then hold it for testing. Another techie friend suggested using a double sided sticker and put the SMD on it sot hat it does not slip away. Using a spring holder is news to me! Many thanks!

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- Yogesh Panchal
  
  September 24, 2020 at 6:58 pm
  
  Sir,
  
  used to say that "Necessity is the mother of invention" this are all the the examples & we are learning it by interchanging/sharing work experience as you have provide me one more tip of double sided sticker........Thanks!
  
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Paris Azis

September 23, 2020 at 2:45 pm

Good job, Yogesh.

These caps are really a pain when they become short circuited.
On top of that, it is terrible that they have no marking on their bodies (and I wonder why)...
The 3 digit smd code used for resistors could very easily be used with them as well, but...who cares?...
Your only chance, in such cases, is to find another one cap within the circuit, having the same dimensions with the failed one and providing the same function as the failed one, in your case here decoupling.
I can hardly see any other alternative for a safe replacement of such failing caps without a schematic.

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- Albert van Bemmelen
  
  September 23, 2020 at 10:33 pm
  
  You are of course very right Paris. A max working voltage marking would be nothing more then necessary. A decent capacity marking is not as important because it can be measured anyhow. The max allowed voltage is harder to determine without destroying these caps. But they are mostly around 100nF to shortcircuit unwanted signals to ground. E-caps on most laptop mainboards are only 6.3V max, but they are always marked.
  
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  - Paris Azis
    
    September 24, 2020 at 4:22 pm
    
    Hi Albert
    
    In any case, if you replace a “no name” ceramic cap of a laptop motherboard with a new one rated to 16V, the replacement is 100% safe.
    The problem is always the capacitance. I have seen many times that such decoupling caps exceed the ordinarily known one of 100nF, reaching the value of 1μF. This makes a huge difference in ripple noise (as an example).
    
    Best Regards
    
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- Yogesh Panchal
  
  September 24, 2020 at 7:11 pm
  
  Paris,
  
  Hearing from you after very long ....
  This caps are Main culprits in Laptops now a days say 70% laptops are having fault because of this Caps.
  You will win the game if you are having same Model /series /family donor-boards.
  Thanks!
  
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  - Paris Azis
    
    September 25, 2020 at 4:41 am
    
    You are right Yogesh.
    Although I am not involved in laptop repairs, I have various other feedback about the behavior of these caps. They also present a high rate of failures in mobile phones as well...
    Perhaps there is something wrong like the “capacitor plague” of the past (with the electrolytic caps failing one after the other)...
    
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Waleed Rishmawi

September 24, 2020 at 4:44 pm

thanks for sharing your experience with us. I enjoyed your article.

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Yogesh Panchal

September 25, 2020 at 2:37 pm

Your welcome! Waleed

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