how to test lcd led backlight?

[budm]

Re: how to test lcd led backlight?

"Would you Please teach me this.......No time limit just for study....I will try it, also.....It's fun...
Question 1: What is the voltage read out ,if you change to two Schottky diodes.
Question 2: What is the voltage read out ,if you change to two Ideal Diodes
Question 3: What is the voltage read out ,if you change to two Zero Bias Schottky Detector Diodes, two resonant-tunneling diodes or two Tunnel diodes .
Question 4: What is the voltage read out ,if you connected series or parallel to DC5V , AC 5V and the high (or microwave) frequence.

Two capacitors or resisters put in series or parallel together, the values , I still make mistakes …. all the time........I'm not straight A student like most Asia's student do....I was a party boy....I's in a Band (called {120DB} U know what that means)........and I graduated by use cheating note …................. have fun....." "We all love Electronic......that keep me out of street, drugs, make millions for me, my job, my career, my every thing"

Well since you seems to skip many lab experiments, and now you have your own company, so why don't you just buy lots of components and do the experiment in your development/engineering lab that way you will never forget what you observe during the experiment, hand on experiment is priceless! I am sure with millions you make you will have good electronics lab at your work place, I am surprised that your lab does not have test equipment for incoming QC to do all kind of component verification instead of the $20 Chinese cloned meter.

https://cdn.badcaps-static.com/pdfs/...559d028ddf.pdf
http://www.linear.com/product/LTC4358
http://ieeexplore.ieee.org/xpl/login...umber%3D663541


I am surprised you did not ask about GUNN DIODE, VARACTOR DIODE, PIN DIODE, STEP RECOVERY DIODE, PELTIER DIODE, ETC.

[keeney123]

Re: how to test lcd led backlight?

This should be a interesting answer.

[budm]

Re: how to test lcd led backlight?

I do not take people seriously when they are start bragging about millions they make. Millions and use $20 Chinese cloned or use 120vac Voltage on the working LED and ending damaging the LED, so if the LEDs were good but then the test caused it to fail, that is not a good way of testing.
Post 66:
"The LED-screen-light works good ! So I destroy it with 110AC . Now, one LED is blow out, another LED is no light but look OK. Screen won't come on anymore........."
You would think someone with EE will know what will happen. May be he did not have hand-on in the lab when the LED subject comes up.

[stj]

Re: how to test lcd led backlight?

maybe, but experiments are fun and you can test theory's that would be laughed at otherwise.

powering stuff with a single wire is always interesting.

[budm]

Re: how to test lcd led backlight?

It is not really single wire since that high Voltage for CCFL tester is running at high frequency and high Voltage, the stray capacitance will come into play. The current leaves the source and have to flow back to the source to complete the circuit otherwise there will be no current flow.

[Peter Chiu]

Re: how to test lcd led backlight?

How to test LED screen and learn Basic Electronics

…............Pyramid needs a Good Foundation............

No background music PLS ! When you study hard , no music is allow.

This 101 series Basic Electronics is for beginner who want to lean how to test LED screen and basic electronics . (specially for me) .

PS: When U see <<<<<< >>>>>>>>> is means kinda import......

OK.............Lets do it.........…..


Basic Electronics
2.* BASIC ELECTRICITY
ELECTRICITY AND MAGNETISM BASICS*-*It all starts with the electrons moving around atoms. Electricity is the movement of electrical charge from one place to another.* Electric charges do not exist without their associated electric and magnetic fields. This module will introduce you to many of the basic concepts involved with electricity and magnetism.**
MATTER*-*Matter is physically everything that exists that we can touch and feel.* <<<<Matter consists of atoms.>>>>>*Now*we will introduce you to the structure of atoms, talk about electrons and static charge, moving charges, voltage, resistance, and current. You*
3. BASIC ELECTRONICS

Now that you have a general background in electricity and moving charges you can move on to learning more about basic electronics. Electronics puts a knowledge of electricity to useful work. Electronics applies electrical current flow of electrical charges to circuits to accomplish specific tasks. Amplifiers can be constructed from glass "tubes" containing metal elements, or more commonly today with solid state diodes, transistors, or integrated circuits. <<<<<<An amplifier is simply a device or circuit that takes a small signal input and controls a larger current as it output>>>>>>>>. The input signal voltage is small and the output voltage is larger - amplified. A circuit containing wire conductors, resistors, capacitors, inductors and amplifiers can be configured in many ways to build various electronic circuits like oscillators, digital logic circuits, computer circuits, television and video circuits and much more. <<<<< An oscillator>>>> by the way is just an amplifier<<<<< with some of the output fed back into the input.>>>>> Sounds like a perpetual motion machine but it isn't as the amplifiers power supply is providing the additional energy that is lost in the circuit and keeps the circulation, i.e. oscillations going.

Basic electronics is all about electrical components and the circuits consisting of those components . Common components are resistors, capacitors, inductors, transistors, and integrated circuits. You will find each of these components described in detail in the following numbered sections. The components are interconnect with conductors, either physical wires or printed circuits. The components make up linear analog amplifiers, oscillators, and filters as examples. They also can be configured to create digital logic circuits such as memories, gates, arithmetic units, and central processing units. So you will find basic electronics in every computer, mp3 player, radio, TV and may other appliances in your home, car, or on your body. Each circuit has a job. Components are interconnected to perform a specific task. First learn about each individual component and how it works then learn about how to interconnect them to make useful end products. Continue your study by reading the numbered sections to follow. will learn about <<<<<<<the properties of magnets>>>>>> and how magnets are used to produce electric current and vice versa.*All matter can be classified as being either a pure substance or a mixture.* Matter can exist as either a solid, liquid, or a gas and can change among these three states of matter.* In electronics the most important matter are <<<<<<<<conducthttp://101science.com/Radio.htmive metals, non-conductive insulators, and semiconductors.>>>>>>>>>>*(Yes, all this is a simplification on purpose to keep the subject easier to grasp. We will leave deeper thoughts to the study of nuclear physics.)
ELECTRICAL CHARGE*- <<<<<<<<<Any object or particle is or can become electrically charged.*>>>>>>>> Nobody*completely understands what this charge consists of but we do know a lot about how it reacts and behaves.* The smallest known charge of electricity is the charge associated with <<<<<<<<an electron.*>>>>> This charge has been called a "negative" charge.* <<<<<<<An atoms nucleus>>>>>> has a positive charge.* These two un-like charges attract one another.* Like charges oppose one another.* If you had 6,250,000,000,000,000,000 electrons in a box you would have what has been named; one coulomb of charge.* An easier way of thinking about a large number like that is called "powers of ten" and it would look like this <<<<<<<6.25 x 10^18electrons.>>>>>>* It is simply a way to let you know to move the decimal point to the right 18 places.* When electrical charges are at rest, meaning they are not moving, we call that static electricity.* If charges are in motion we then have a flow of charge called <<<<<<electrical current.*>>>>> We have given the force that causes this current a name called <<<<<<"electromotive force" >>>>>>>>and it is measured by a unit called a volt (V).* The unit of measurement of the current (I) or movement of the charge is called an ampere.* The resistance, or opposition, to current flow is called an ohm (R).
https://www.youtube.com/watch?v=vVdBtSRr0UE

ELECTRICAL*FIELDS-*Around*every*charge is an electric field.* <<<<<<<With every electric field there is a magnetic field.*>>>>>> While we can't see these fields, or yet know exactly what they consist of, we can measure them with instruments and tell a great deal about their behavior.* We can then use this knowledge to our benefit.* The design and construction of electric motors, computers, radios, televisions, stereos, and many other electrical and electronic devices depend upon a knowledge of these basic principles of electricity.* As you can see we have given names to these phenomenon to make it easier for us to study and use.* We could have called them Dick, Jane and Mary but instead we named them for the scientists that discovered or first studied them; Volt, Ampere, and Ohm.* Mr. Volt, Mr. Ampere, and Mr. Ohm spent many years of their gifted lives studying electricity.* They were not alone however as many other scientist were studying and learning more about electricity as well.
WATTS - POWER*- What is a watt?* <<<<<<<A watt is the International System unit of power equal to one joule per second.**A joule is a*unit of electrical energy equal to the work done when a current of one ampere passes through a resistance of one ohm for one second. >>>>>>>The symbol used for a watt is "P" for power.* Power in watts is found by multiplying a circuits current (I) times its voltage (V).** You will learn more about power in watts in the ohms law section below.**

P - I*V*

https://www.youtube.com/watch?v=-NdjoLqriJU


If you don't have a clue as to what electrical current and voltage are - read on.* We will cover that shortly.
Moving electric charges are the heart of basic electronics.* Knowing what moving charges are and how various electronic components affect the moving charges is the foundation of basic electronics.* View the*videos and continue on down the page.* These are the basic building blocks of understanding "Basic Electronics".
https://www.youtube.com/watch?v=14YIm4UK9LA
3.* BASIC ELECTRONICS
Now that you have a general background in electricity and moving charges you can move on to learning*more*about basic electronics.* Electronics puts a knowledge of electricity to useful work.* Electronics applies electrical current flow of electrical charges to circuits to accomplish specific tasks.* Amplifiers can be constructed from glass "tubes" containing metal elements, or more commonly today with solid state diodes, transistors, or integrated circuits.** An amplifier is simply a device or circuit that takes a small signal input and controls a larger current as it output.* The input signal voltage is small and the output voltage is larger - amplified.* A circuit containing wire conductors, resistors, capacitors, inductors and amplifiers can be configured in many ways to build various electronic circuits like oscillators, digital logic circuits, computer circuits, television and video circuits and much more.* <<<<<<<An oscillator by the way is just an amplifier with some of the output fed back into the input.*>>>>>>Sounds like a perpetual motion machine but it isn't as the amplifiers power supply is providing the additional energy that is lost in the circuit and keeps the circulation, i.e. oscillations going.
Basic electronics is all about electrical components and the circuits consisting of those components .* Common components are resistors, capacitors, inductors, transistors, and integrated circuits.* You will find each of these components described in detail in the following numbered sections.* The components are interconnect with conductors, either physical wires or printed circuits.* The components make up linear analog amplifiers, oscillators, and filters as examples.* They also can be configured to create digital logic circuits such as memories, gates, arithmetic units, and central processing units.* So you will find basic electronics in every computer, mp3 player, radio, TV and may other appliances in your home, car, or on your body.* Each circuit has a job. Components are interconnected to perform a specific task.* First learn about each individual component and how it works then learn about how to interconnect them to make useful end products. Continue your study by reading the numbered sections to follow.

Thanks ….... We will continue tomorrow........Any questions will answer at the end of 101 series of The Basic Electronics........

[budm]

Re: how to test lcd led backlight?

"An oscillator by the way is just an amplifier with some of the output fed back into the input.*>>>>>>Sounds like a perpetual motion machine but it isn't as the amplifiers power supply is providing the additional energy that is lost in the circuit and keeps the circulation, i.e. oscillations going." Negative or positive feedback? Which one? Since you were in the band you are familiar with microphone feedback, right?
What happen to the diodes testing?

[stj]

Re: how to test lcd led backlight?

if you use a high enough frequency you can power stuff without a return wire because your load becomes a resistive antenna.
it only works at loow current though - probably.
i dont know anyone brave enough to generate high frequency high current power for such an experiment.
tesla probably did it daily though.

[budm]

Re: how to test lcd led backlight?

Telegraph using Earth as the return.
http://w1tp.com/pertel.htm
The WIRES were usually made of copper because it conducted electricity better than other metals. It was discovered in the 1830's that the second wire could be eliminated by using the earth as an electrical conductor. From that time on, only a single wire was necessary to cover the distance between a key and an electromagnet.

http://physics.stackexchange.com/que...plasma-globe-c

Some interesting reading here too:
http://ecmweb.com/content/rf-lightin...d-illumination

[budm]

Re: how to test lcd led backlight?

BTW, here is the example of WHITE LED with protection diode.

[keeney123]

Re: how to test lcd led backlight?

"When electrical charges are at rest, meaning they are not moving, we call that static electricity."
I thought electrical charges not moving was called voltage. Or potential. Static electricity are charges moving, building potential and when things are at rest we call it equilibrium as all forces are counteracted by each forces involved.

[budm]

Re: how to test lcd led backlight?

http://www.loc.gov/rr/scitech/mysteries/static.html

"Static electricity is the result of an imbalance between negative and positive charges in an object. These charges can build up on the surface of an object until they find a way to be released or discharged. One way to discharge them is through a circuit."

[Peter Chiu]

Re: how to test lcd led backlight?

...........Half knowledge is dangerous......So. I ain't answer no questions until the end of the courses.....
Special thanks to BUD M's suggestion, I'll do the lab to each course.

4. RESISTANCE -
RESISTORS AND RESISTOR CIRCUITS*- Resistance is the opposition to current flow in various degrees.* The practical unit of resistance is called the ohm.* A resistor on one ohm is physically very large but provides only a small resistance to current flow. A resistor of one million ohm's is physically small but presents a high resistance to current flow. >>>>>>>A resistance that develops 0.24 calorie of heat when one ampere of current flows through it for one second has one ohm of resistance.<<<<<<* The unit of resistance is often represented by >>>>>the Greek letter omega.*<<<<< Resistors are often made of thin layers of carbon or lengths of small copper wire.* They can also be thin deposited layers of metallic material.* An image of a few resistor types is shown below.
What is electrical current? Electrical current, represented by the letter "I" in formulas, and it is the flow or rate of electric charge. This flowing electric charge is typically carried by moving electrons in a metallic conductor or electronic components such as resistors or transistors as an example. The unit of electrical current is the ampere, named after >>>>>>>a french mathematician, Andre Marie Ampere. <<<<<<<What is electrical voltage?* Electrical voltage is represented by the letter "V" in formulas and it is the electrical pressure a moving charge is under.* In the case of a static charge, one that is not moving, then voltage is the potential difference or pressure of the charge.* The relationship between current (I), resistance (R), and voltage (V) is represented by the formulas developed in Ohm's law.* We will study that in section 5 below.


..........I can't copy and paste ….any more!......Too many PICs and videos
SO let's go to.........http://101science.com/Radio.htm........ chapter 4....U need to sturdy ur'self.
................................................................................................................................................................................................................................................................................................................................................................................................


OK...Lt's go back to chptr 4
4. RESISTANCE

{For more than two resistors connected in parallel a <<<<<more difficult equation >>>>>>>must be used.}

I really don't know what they're talkin' about ... try my equation more easier….. in school my equation score 100%.......equation is fun..........I think they need to go back to school,also. They don't even know... how to teach!........

R=150 ohm ( Brown /green/brown ) 10%

>>>>>>>......my equation R=1/(1/R1+1/R2+1/R3.......).......<<<<<<<<<

75 ohm =1/(1/150+1/150) ...... pic1 (two resisters 150 ohm)
50 ohm =1/(1/150+1/150+1/150) ........pic2 (3 resisters 150 ohm)
37.5 ohm =1/(1/150+1/150+1/150+1/150.........) ........ pic3 (4 resisters 150 ohm)

Example: 47k ohm and 33k ohm resistors
R=1/(1/R1+1/R2)
R=1/(1/47 +1/33)=(copy and paste to Google and you get answer straightaway) =19.39 k ohm

Tips:
......So ..when...U need .........smaller resister ..................parallel them
..............................................larger resister...................series them

in pics …..U'cn see (the % of error) is multiply , more resistors connected in parallel or series are unpractical.

Old Tips : The carbon resister can be files a little bit ….and the value will go up ….then use super glue seal it.......In case, U in (the missions to the Mar).

For all the beginner...................have fun.......Hasta Mañana



…..............................FOR ADULTS ONLY................................................................

Before I kill myself give me a break....
https://www.youtube.com/watch?v=lp-EO5I60KA

I need something....to.... let my brain take a rest.
https://www.youtube.com/watch?v=LkdodHMcBuc

[keeney123]

Re: how to test lcd led backlight?

http://www.loc.gov/rr/scitech/mysteries/static.html

"Static electricity is the result of an imbalance between negative and positive charges in an object. These charges can build up on the surface of an object until they find a way to be released or discharged. One way to discharge them is through a circuit."

Like how a capacitor charges and discharges.

[Alastair E]

Re: how to test lcd led backlight?

Err--I don't understand......

Whats all this basic electronics stuff to do with actually Testing the LED strips--The Subject Line of the thread...?

Thread seems to have evolved into a basic electronics grounding semester!

[budm]

Re: how to test lcd led backlight?

Err--I don't understand......

Whats all this basic electronics stuff to do with actually Testing the LED strips--The Subject Line of the thread...?

Thread seems to have evolved into a basic electronics grounding semester!

Yes, I know. I will work on my power supply for testing LED and will post the result after I am done.

[Peter Chiu]

Re: how to test lcd led backlight?

….......Keep on........CPT 4: Resistance

<<<<<<<my equation R=1/(1/R1+1/R2+1/R3.......)>>>>>>>>

If R1=R2=R3......are same value (150 Ohm) than will be more easy.............

75 ohm =150/2...... (two resisters 150 ohm)
50 ohm =150/3........ (3 resisters 150 ohm)
37.5 ohm =150/4....... (4 resisters 150 ohm)

IF same value of two resistors put parallel together will be half the one's value.

I will prove to you
but first we change >>>>> R1=a <<<<<<<for easy look

R=1/(1/a+1/a)=1/(2/a)=a/2=means half the a=R1's value=75 ohm

ex:Pick up two 100k resisters parallel together =50k (right-away half the 100k value….)

....................beginners .............................また明日ね。

For Veterans:
Electrical resistivity and conductivity
https://www.youtube.com/watch?v=4rsswT_Rv1M
Intro to Electrical Resistance, Resistors, and Resistivity | Doc Physics
https://www.youtube.com/watch?v=XoI6QmQeAXo
Resistivity
https://www.youtube.com/watch?v=FPZiMVna1ls
Resistivity, Resistance, and Conductivity
https://www.youtube.com/watch?v=bK-9U-9eW_Y

Friendly remind;
You gonna learn all that today, because this is lesson 1

your rewards:
https://www.youtube.com/watch?v=i8rMpN4o-b0

…...Oh.....poor girl...... I'll give you something better than whiskey........ …..my FALT just near by......let's............

[Peter Chiu]

Re: how to test lcd led backlight?

Alastair E:......not just Testing the LED strips....


Unveil…..........The first............The best tools for TV repairman..............



1: Test all sizes of LED screens (7” to 120” screens) are.... good or not?
2: How many LEDs are inside the screen ?
3: which group LEDs is bad ?
4: Is the LED driver work or not ?

Will answer the common questions about { Is my screen bad or the LED power driver bad? }! ......cast you about $40......

Would you believe.. ... A guy ( don't even know Vf =0.7V ) will design a good tester. Even I don't thing so......so I need to study, again......again......

https://www.youtube.com/watch?v=D_P-v1BVQn8 .....but I ain't gay..

Parts on order......waiting for parts.......please be patient..........To be c.....…...

[budm]

Re: how to test lcd led backlight?

"Will answer the common questions about { Is my screen bad or the LED power driver bad? }! ......cast you about $40......" $40 to find out if the driver is bad?
I think we did pretty well on how to find out if the drivers are good or bad:
https://www.badcaps.net/forum/showth...648#post550648
https://www.badcaps.net/forum/showth...led#post546324
https://www.badcaps.net/forum/showth...led#post537873
https://www.badcaps.net/forum/showth...bad+led&page=2
https://www.badcaps.net/forum/showth...led#post546755

[Peter Chiu]

Re: how to test lcd led backlight?

Sorry ! what I mean is not open the LEDs screen. The tester is use to diagnose the problem before you open the screen which may cause (like tab ) more problems.

The screen size getting bigger and bigger, I would not open 85" TV unless I'm 100% sure that is the problem. that's what the LEDs screen tester for...

Let's say another word
not open the screen....by use the tester I will know this ...

1: LED's LCD screen is good or not?
2: How many LEDs are inside the screen ? How much is the current they used to drive screen.
3: Which group LEDs is bad ?
4: The problem is LED driver or screen. I need 100% sure.
5: All the test needs to be done ....less than 10 min
6: We can't cut any wire , If TV get fire, we might get sue .
7: Each in home diagnostic testing ( In home service call ) is around $180 to $320 depend on the size of the TV. Pay for itself in fist visit.
8: The symptom of screen broken always misdiagnosis is failed power supply. New LED TV the LCD screen failed ,broken screen,water damage ,screen manufacturer defect, look good but will cause wrong diagnostic and waste a lots company resource. This tester will mend this problem.

With more and more big size LED TV in Walmart ......the tester is the future ...and.... The tester is made in USA....