SMD Resistor or Surface Mount Chip Resistor is an electronic component with the properties of both obstruction as well as resistance. The property of this component is called resistance.
What is Resistance?
The obstruction or resistance created by any matter in the flow of current is called resistance.
What is the Graphical Symbol of Resistor?
The Graphical Symbol of Resistor is :
Which Alphabetic Character Denotes a Resistor?
A resistor is denoted by the character: R
What Is The Work Of A Resistor?
The work of a resistor is to decrease current.
What is the Unit of Resistance?
The unit of resistance is: Ohm
What is the Power Rating of Resistor?
The power rating of resistor is Watt.
What does a SMD Resistor looks like?
A SMD resistor appears black from top with some blue colour. The colour at the bottom is white.
Points to Remember:
- A resistor never gets short.
- Resistor can be open.
- Value of resistor can be high.
- Resistor is available with or without code. Mostly resistors without code are used in mobile phones.
- R and E alphabets in the resistor denote Ohms.
Different Types of SMD Resistors
- Network Resistor: Combination of more than one resistor groups is called network resistor. They are made in a single package.
- Chip Jumper (Zero Ohm) Type Resistor: This type of chip resistor is used as jumper in mobile phones.
- Thermistor-Type Resistor: The rating of this type of resistor depends on temperature. It is black in colour from all sides. These resistors are of two types – NTC Thermistor (Negative Temperature Co-efficient type Thermistor) and PTC Thermistor (Positive Temperature (Co-efficient type Thermistor).
- LDR (Light Dependent Resistor): This resistance is dependent upon light. Resistance of a LDR may be several mega Ohms in dark, but is reduced to few Ohms under light.
Coding of SMD Resistor
Generally a number equivalent to three band color code is written on a resistor. Like resistors of normal terminal, a 4 digit code is provided to denominate tolerance. First 2 or 3 digits denote the first two or three digits of values of the resistor and the third or last digit represents the numbers of zero. R is written before or after the value to denote the position of decibel point in the resistor below 10 Ohm value. Read the following examples:
- Code : 330 = 33 Ohm
- Code : 221 = 220 Ohm
- Code : 683 = 68000 Ohm or 68 K Ohm
- Code : 105 = 10,00000 Ohm or 1 M Ohm
- Code : 8R2 = 8.2 Ohm
- Code : 1000 = 100 Ohm
- Code : 4992 = 49900 Ohm or 49.9 K Ohm
- Code : 16234 = 162000 or 162 K Ohm
Tolerance or SMD Resistor
During manufacturing of resistors, some deficiency or excess may take place in its value. The tolerance of resistors used in mobile phones is almost zero.
How to Check a SMD Chip Resistor using a Multimeter
If the value of a resistor to be checked is 100 Ohm, then place probes of the Multimeter at both the soldering tips of the resistor and select knob of the Multimeter at 200 Ohm. Value of the resistor is displayed on the display screen of the Multimeter. If only 1 is displayed on the screen then it means that the resistor is OPEN and if the reading is too high then it means that the resistor is out of order or it is faulty. Resistors do not get shorted. Value of a resistor is considered OK within its tolerance limit.
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By Santosh Das | Mobile Cell Phone Repairing