Resistor Color Code

                                                       Resistor Color Code

The electronic color code is used to find out the ratings and values of different electronic components  usually in case of resistors but also for capacitor, inductors and others.

How to read the code??

As shown in the given table different colors have their specific code.Now we will discuss and demonstrate with the help of diagrams that how to read these codes.Most of the resistors have four color bands while some have five or six bands.

Band #1 is the first significant figure of the component value.

Band #2 is the second significant figure of the component value. (In case of five bands the third band is also the 3rd significant figure of the component value.)

Band #3 is the decimal multiplier.

Band #4 if present then it shows the tolerance value.In case band #4 is not present than the tolerance value will be taken as 20%.

Now for a better concept let us take an example of a resistor which has (yellow violet red and gold) color code combination. Yellow color relates to the digit 4 as shown in the table, so the first digit in the value of resistance is 4.Now the violet color is related to the digit 7 so the second digit is 7.And red color is related to the digit 2 in table and also the 3rd digit represent the decimal multiplier.So this value will become 4700.Now the fourth color which is gold represents +-5% tolerance.So the value of the resistance lies between 4465 and 4935.

For remembering that which code is related to which digit I recommend a sentence, the first letter of each word in sentence represent a color.The sentence is "Big Boys Race Our Young Girls But Violet Generally Wins".

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Laptop Dead Motherboard Fix

                   Laptop Dead Motherboard Repair

This article is only for the experienced people who know well, how to assemble and disassemble laptops.I will explain the basic troubleshooting of the motherboard. If your laptop doesn't start, Is it bad power jack or power fuse.Let's say when you start your laptop put the charger in and press the power button on and it doesn't show any reaction.

What is the possible error??

First of all you should check the adapter by the help of multimeter. If it is working well then remove the top cover of the laptop.As you can see the picture given below the power adapter plugs into the DC-IN (DC-IN is the power jack at the back side or on other sides of your laptop.) of  power jack which is connected to the motherboard with the help of harness.

In some motherboards the DC-IN power jack is directly soldered with the mother board.
Now plugin the power adapter in the socket and check the voltage with the help of multimeter at the point where DC-IN jack or DC harness is connected to the motherboard. Now If you are reading the same value of voltage as viewed in case of adapter then DC-IN jack or DC harness is working properly and the fault exists in the motherboard.And if there is no voltage then the DC harness must have to be replaced.
Then you should also check the fuse using multimeter which is located near the DC-harness.If the fuse is bad then after replacing it the laptop will start.

If the problem still exists, then you will have to disassemble the laptop and separate motherboard for testing. You have to clean all the parts from dust as we know that dust becomes an blockage  towards the conduction. So you should always keep in mind that whenever you open the laptop clean it from dust completely.Now take a overview that your laptop has any loose connection or poor solder.If you didn't find any loose connections or poor solder then just for contentment re-solder all the SMD components specially on the power section. 
Note: Now a days all the laptops are designed on a surface mounted device or SMD mode and this rarely have loose connections.But re-solder only for your satisfaction.
After doing all this now you should insert the power plug in and check all the electronic components that can be tested with multimeter so you should check whether if there is any component that causes any short circuit problem.Now the only parts you have not tested are dc power jack and fuse.
Now test the dc power jack from input to ground as in my case the problem was existing here.It was really shorted.I used x1 range of multimeter to test the fault.Also on further inspection i found a shorted diode.The reason behind the short circuit of dc power jack is the shorted diode.Replacing the diode brings my laptop back to life.

Mobile Phone Repairing Tools

Mobile Repairing Tools

Mobile repairing requires a number of tools and you should be familiar with all of them. Then you are able identify frequently that which tool is to be used.The following article introduce the types and uses of most frequently used tools. 

Soldering Iron: A Soldering iron is a hand tool used for general purpose soldering. It is used to solder components like capacitors, transistors, resistors, speaker, voltage regulator  etc.It uses a heating element to produce heat from electricity.A 35- 50 watts Soldering iron is just perfect for general mobile repairs.  A good  soldering iron should be easy to hold and the one that does not burn your hands . Their is a large variety of soldering irons available in the market choose one that suits your needs. And never compromise on quality.

Solder Wire: Solder wire is used to solder electronic components 
like ICs, capacitors, transistors,    etc.It is basically a metal alloy(Tin and Lead). Available in a range of thicknesses usually containing flux in the core. 0.5 mm is best for mobile repairs. Lead free solder is also available to avoid environmental effect.

Soldering Station: It is temperature controlled soldering instrument consisting of two parts A station (Temperature controller) and soldering Iron or soldering head (with temperature sensor at its tip).It is much more useful then a traditional soldering iron in mobile or other electronic repairs.It makes the art of soldering much easier and faster.

PCB Holder: PCB Holder is used to hold printed circuit board strongly while doing repairing specifically soldering.Thus making it easier to control the board while repairing work.

PCB Cleaner: PCB Cleaner is used to clean a printed circuit board.It removes dust and rust.It also removes shortage caused by liquids(water damage).

Jumper Wire: It is a thin coated copper wire most commonly used to apply jumper from one point to another on PCB.Coated with insulating layer to avoid shortage.Jumpers are commonly applied to solve a lot of problems.

Screwdriver: It is a commonly used tool to loosen and tighten screws.And used frequently in mobile repairing job.You should always have a set of screw drivers all time with you when doing repair.An important character of a good screw driver is a hard tip. 

Tweezers: Tweezers are used to grasp electronic components specially ICs when Soldering or Desoldering.A good tweezer should not be very hard that you have to press by a large force it should lose and easy to use.

Long Nose Pliers: It is used for bending and cutting purpose.Their longer nose makes it easier to reach into cavities where cables are stuck.These are not essential tools for mobile.

Point Cutter: These are used for cutting purpose.

Blade Cutter: Blade cutter is used to remove coverings from wires and also from jumper wires.

Brush: A brush is used to clean mobile board removing dust or other materials.A good quality brush is always needed in mobile repair.

Mobile Opener: It is used to open mobile body.Opening a mobile using mobile opener is more safer.Otherwise you may sometimes break the mobile body.

Flux Liquid: Flux liquid is used to clean board after soldering or for cleaning pins of components. Use of flux liquid is important as it enhances the efficiency of soldering.

Paste Flux: Flux paste is used in soldering.It is used for smooth soldering and to spread the solder more easily.

Solder paste: Solder paste is used for attaching pins of ICs to attachment points on printed circuit board.It is a thick viscous paste,The quality of solder paste is very important otherwise a low quality solder paste can cause many problems .

Cleaning Sponge: It is used for cleaning the tip of soldering iron.Basically a wet sponge removes any solder pieces from hot tip.It is very important to keep your soldering iron clean so a cleaning sponge is everything you need for the purpose.

Desoldering wick: Or Desoldering braid is copper wire coated with flux.It is placed over soldered connection which is to be removed when heat is supplied by soldering iron then melted solder is attached to the braid.

Screwdriver Kit: A screwdriver kit contains a number of screwdrivers with a variety of tip shapes used in assembling/disassembling of mobiles.

Desoldering pump: A desoldering pump is basically a solder sucker having a piston pressed and locked in place which is triggered by a button producing vacuum inside the pump and sucks the solder. 

Multimeter: A multimeter is an electronic instrument used to measure quantities like voltage, current , resistance etc.Their are two main types analogue and digital based on display.Analogue displays with a needle on printed scale.While a digital multimeter has a LCD for display. 

SMD Rework Station: SMD Rework Station is an instrument that releases hot air which is used to solder/desolder ICs or for heating ICs.It has a temperature control system which controls temperature of released air.

Ultrasonic Cleaner: It is used to clean mobile board(PCB).It removes shortage caused by fluids.

BGA Kit: It is used for reballing of ICs.

Magnifying Lamp: It is used to see a magnified picture of mobile board.As there are many small components on PCB of mobiles which can not be seen with naked eye a magnifying lamp helps you in this respect.Their are many types of magnifying lamps having different magnification values so choosing one that suite your needs is important.

DC Power Supply: Provides a range of regulated DC voltages and can be set according to the requirement.Usually most repairers use it to turn ON a mobile without battery.

Infrared Workstation: It is used for the same purpose as a SMD rework station But the main difference is that it releases heat in the form of infrared radiation.Thus it precise and targeted in action heats those components only which are needed.And do not heat the neighboring components.

Wrist Strap: It is an anti-static static device used to safely ground a person when working on sensitive electronic component to prevent electrostatic discharge.It consists of a stretchy band of fabric with fine conductive fibers woven into it, attached to a wire with a clip on the end to connect it to a ground conductor.

Electronic Repairing Tools

Tools For Electronics Repairing

This article introduces you to the tools used for the electronic troubleshooting.For the basic operation you will need simple and mostly used  tools while for the complex operations you will have to invest some special kind of tools.
Following are the tools used in electronics.

SOLDERING IRONS:

What is soldering iron?

A tool having metal tip at the end which gets hot up to 800 degree Fahrenheit or even more. You can also adjust the temperature of a good metal. The purpose of the metal tip is to transfer heat to the soldering wire so that it melt and solder joint is formed and the two individual components holds together. Soldering guns are also available but they are used when you have to work on a larger scale.

How to use a soldering irons?

Hold the soldering iron in your dominant hand and soldering wire in the other hand. Now touch the soldering iron and the solder wire at the place where you want to make a solder joint. Take a better idea from the diagram given below.

Safety measures:

Be sure to wear safety glasses, keep loose clothes, and not to touch your fingers with the metal.its better to put gloves in your hand.

SOLDER WIRE:
Solder wire is used to solder electronic components like ICs, capacitors, transistors,    etc.It is basically a metal alloy(Tin and Lead). Available in a range of thicknesses usually containing flux in the core. 0.5 mm is best for mobile repairs. Lead free solder is also available to avoid environmental effect.

SPONGES:

It is used for cleaning the tip of soldering iron.Basically a wet sponge removes any solder pieces from hot tip.It is very important to keep your soldering iron clean so a cleaning sponge is everything you need for the purpose. Make sure the metal tip is clean otherwise there will be a blockage of heat transfer.

SOLDERING IRON HOLDERS:

When you have to put the soldering iron aside, as the tip is red hot and may cause burning and for that purpose you need soldering iron holder. The holder is often form into a spiral with a lot of space to radiate the heat.

DESOLDERING WICK:
Or Desoldering braid is copper wire coated with flux.It is placed over soldered connection which is to be removed when heat is supplied by soldering iron then melted solder is attached to the braid.

HEAT GUNS:

Some times it becomes necessary to provide heat to solve the problem. then heat gun is used which generates a stream of hot air with a temperature ranging from 100-500 degree Celsius. one should be careful while using the heat gun as it may cause the damaging of the plastic material.

DC POWER SUPPLY:
Provides a range of regulated DC voltages and can be set according to the requirement.

FREEZE SPRAYS:
Freezing sprays are the cooling agents for cooling down the high temperatures.For the rapid cooling of circuit components different chemicals such as Freon are used.Some coolant may generate static charges of thousands of volts which may damage the circuit so be careful in this regard. So buy a brand that is specified as anti-static.

DENTAL MIRRORS:
Dental mirrors are used when you have to look into out-of-the-way places i.e when components are located under the belly of CRT.

SCREW DRIVERS:
For electronic troubleshooting a set of good screw drivers is required. Screws are made in different sizes and shapes and can be turned over by the help of  the screwdrivers of the corresponding sizes and shapes.Specified size of the screwdriver should be used. Power screwdrivers are also used for electronic troubleshooting.

LONG NOSE PLIERS:
Once the components are desoldered from the PCB then long nose pliers are used to pick them up.It is used for bending and cutting purpose.Their longer nose makes it easier to reach into cavities where cables are stuck i.e the components located under the neck of CRT are very difficult to remove without long nose pliers.

WIRE CUTTERS:
Wire cutters are used for cutting wires, wire ties and lead on large parts.

WIRE STRIPPERS:
When you have to make connections, the wire should be bare at the place of connection. In order to remove the plastic cover from the wire, wire strippers are used. You may say that this cover could be removed by the help of wire cutters but it will cause damage and fatigue in the wire which will reduce the wire conductivity.

MAGNIFYING LAMP:
Magnifying lamp not only provide light but also gives magnified view of the component under consideration.
So that you may read the information provided on the components i.e small resistor color codes, SMD resistor values or capacitor values etc.

SPRAY CLEANER:
Sometimes the dust accumulated on the circuit  components may effect the operation of the circuit.In order to remove the dust and to clean the circuit, spray cleaner is used. However if the problem still persists than you must have to replace the component.

CLEANING BRUSH:
You may use a cleaning brush or toothbrush for overcoming a bad connection problem in the PCB. Initially the fault may be detected. Simply run the cleaning brush over the circuit until you put the bad connection into working.

In addition to the above mentioned tools you may require some other tools like hammer, nail extractor or even drill machine for installation and dismantling work.However it depends on what type of job you are doing.