Laptop Screen Goes Black - 2 Reasons for Black Laptop Screen Problems

One of the most common reasons why a laptop screen goes black is because of impact damage. This can happen when the laptop is accidentally dropped or bumped into.
  • Apart from a cracked screen & display chip damage, the whole monitor goes black and doesn't respond when turned on.
  • If the damage is superficial, you can get away with simple screen replacement... Get a replacement screen from Ebay and install it in place of your damaged laptop screen.
  • I've done this on laptops ranging from Dell, HP, Acer and Toshiba. Just make sure you get a screen that's compatible with the monitor size & cable connectors of your current laptop.
Another reason for laptop screen problems is a failed backlight bulb.
  • Think of the backlight as a thin fluorescent tubelight that powers up the monitor screen. Most backlight bulbs have a lifespan of 3, 5 or 7 years but you might notice the screen go dim & dark as early as 2-3 years.
  • A failing backlight can also give out a pinkish hue which means all the colors on your screen become pink.
Remember that just as your laptop screen goes black, it can also go white. Black screen is a sign of backlight failure while white screen indicates a loose connection between the video cable and the laptop screen.

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How To Repair LCD Monitors Like A Pro
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Sanwa Digital Multimeter and Yokogawa Digital Multimeter - Quick Electronics Notes on DMMs

Both multimeters are from Tokyo, Japan and products of the Sanwa Electric Instrument Co., Ltd and Yokogawa Electric Corporation respectively.
I have used both kinds of multimeters for electronic testing -- Sanwa multimeters for wider & quicker testing projects and Yokogawa multimeters for intensive & complex troubleshooting.

What I like best about Sanwa is the convenient range of pocket DMMs that I can carry around wherever I go. PM3, PM11 and the newer PM33 are some examples of this model type with an accuracy of between 0.7-0.8%

Other more advanced models from Sanwa include PC5000a (very accurate), CD771 and CD-800a -- which is quite popular in Singapore.

Among Yokogawa's test instruments, I like the 7555 & 7561 series of digital multimeters.

Get the insider knowledge on how multimeters are used in actual testing. Includes projects & case studies. Click here to know more.


Dry Joints in LCD Monitor Circuit Boards

When faced with bad display problems in LCD monitors, the usual suspect is the backlight (the CCFL tube that lights up the screen).

However, in some cases, it is also possible that the problem may be bad solder joints in the monitor's circuit board.

I have seen it happen in some of the brand-name 17" and 19" LCD monitors that were 3-5 years old. On testing, I found that the backlight was working fine. But when I probed a little, I found that dry joints were causing the display problem.


LCD Monitor Inverter Board | Input-Output Voltage for the CCFL Backlight Bulb

CCFL stands for Cold Cathode Fluorescent Lamp. Its function is to light up the LCD monitor screen when a high-frequency current is passed through it.

The power circuits of this lamp are present in the monitor's inverter board, also called the SMPS board. It is called the inverter because it converts low-voltage DC input to high-voltage AC output.

To light up the backlight, you need a 12V DC input. The SMPS board then converts it to a high-voltage AC output in the range of 800-1000 volts. This in turn powers the backlight bulb.


ESR Meter Test for Capacitors - The Use of ESR Meter Readings in Electronics Testing

One of the most common problems in electronic circuit board testing is the case of defective capacitors. This has a series of side effects ranging from power supply problems to unusable or damaged components. 

This is where an ESR meter (Equivalent Series Resistance meter) can be used to test capacitors before they have a chance to create problems.
  • Under ideal conditions, the ESR value of a healthy capacitor is close to zero. But corrosion and drying causes the ESR value to move up slowly. This usually happens after a few years of usage.
  • Eventually, the capacitor itself suffers from voltage drops, increased heating and expected failure.
  • Once out of service, this bad capacitor has a cascading effect on other components, which  suffer from proxy damage.
  • You can prevent such electronic failures by locating capacitors whose values are high, and replacing them in time.


Flickering Laptop Screen - How to Fix LCD Laptop Screen that Flickers Randomly

When a standalone LCD monitor flickers randomly, the problem is usually the backlight. When the same thing happens in a laptop, the cause is a defective ribbon connector cable.

Remember that in a laptop the display screen is separate from the main case that contains the keyboard, hard disk and other electronic parts.

The laptop screen is embedded into the lid of the laptop, and by constant opening and closing, the LCD ribbon connector cable gets worn out.

Once the damage sets in, the cable is unable to relay video signals properly, and so the screen images flicker randomly.

Luckily, there's an easy fix for this: Just replace the ribbon connector cable with a compatible part from an OEM manufacturer. It usually costs $15-20 and is far cheaper than replacing the whole screen.


Power Supply Electronics Books - Top 5 Books on SMPS Design, Troubleshooting and Power Electronics

Power electronics is an interdisciplinary mix of electrical & electronics engineering.

At its core, it deals with the conversion and supply mechanics of delivering the right amount of voltage, to the right component, in a manner that is both precise and automated.

This technology is used in everything from SMPS circuit boards in computers to large-scale electrical transformers in power plants.

Here's my own list of Top 5 books in the field of SMPS & power electronics:

1. Switching Power Supply Design by Abraham Pressman, Keith Billings & Taylor Morey

2. Fundamentals of Power Electronics by Robert W. Erickson & Dragan Maksimovic

3. Power Electronics: Converters, Applications and Design by Ned Mohan, Tore M. Undeland

4. Troubleshooting Switching Power Converters by Sanjaya Maniktala

5. Power Supply Cookbook by Marty Brown

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