Surface Mount Transistor
Yesterday's post was about the link to Martin Pickering's website on smd. Today i will share with you some tips on surface mount transistor cross. Surface mount transistor cross is valuable piece of information for every electronic repairer to find out what is the actual data in it. It could be a transistor, resistor, diode, capacitor or even a field effect transistor. Without knowing what the actual part is just like shooting in the dark. A wrong replacement not only cause the equipment to malfunction, it may also sometimes blow the surrounding parts. This is due to you have replaced the wrong part number with different specification. Surface mounted components often consist of more than one component in the single chip, such as transistors, base and bias resistors.
Leadless transistor chips
The surface mount transistor cross are represented on the board as a three legged triangle. Always find out the manufacturer's transistor drawings to determine what transistor has the base and collector, base and emiter terminals on one side. In most of today's electronic equipment, the leadless transistors have the base and emitter terminals on one side and the collector on the other side (middle). The transistors can have letters and numbers representing the value of the transistor, on top of the part. Remember, these components are very tiny and fragile (handle with care) and can easily be mistaken for a three legged diode. Confirm the main board and service manual for information on mounted compoenets.
Digital transistor chips
Nowadays you will find more digital transistors in many electronic equipments. The digital transistors are either NPN or PNP, with base and bias resistors.If you repair LCD monitor, you can find several different types of digital transistors. The two most common digital transistors used are PNP-DTA124EK with internal resistor of R1 (22 ohm) and R2 (22 OHM). The NPN type part number is DTC144EK with internal resistor of R1 (47 ohm) and R2 (47 ohm). Another number for NPN is DTC124EK with internal resistor of R1 (22 ohm) and R2 (22 ohm).
Testing surface mounted transistor
If the surface mount transistor do not have any internal resistor in it (which is very rare) then you can check the transistor the same way you checka bipolar transistor. An analog multimeter will do a great job in measuring transistor. However, if the surface mounted transistor consists of internal resistor just like the digital transistors, there is no way you can check it. This is due to the 'extra' resistance when measuring the transistor. Thus the reading that you get will not be accurate. The only way to test it is to swap another similar transistor with the same part number. After many years in electronic repairing line, i found that digital transistors are very reliable compare to the surface mounted type. Not only the surface mounted transistor are small, the part number sometimes are hard to recognize even with a magnifying glass. One more weakness about the surface mount transistor is that it can burnt easily when excessive current passed thru it. This will even make your repair work difficult as you could not see the part number. Even with the help of surface mount transistor cross there is no way to identify the component unless you have the similar model of the equipment with you.
Leadless transistor chips
The surface mount transistor cross are represented on the board as a three legged triangle. Always find out the manufacturer's transistor drawings to determine what transistor has the base and collector, base and emiter terminals on one side. In most of today's electronic equipment, the leadless transistors have the base and emitter terminals on one side and the collector on the other side (middle). The transistors can have letters and numbers representing the value of the transistor, on top of the part. Remember, these components are very tiny and fragile (handle with care) and can easily be mistaken for a three legged diode. Confirm the main board and service manual for information on mounted compoenets.
Digital transistor chips
Nowadays you will find more digital transistors in many electronic equipments. The digital transistors are either NPN or PNP, with base and bias resistors.If you repair LCD monitor, you can find several different types of digital transistors. The two most common digital transistors used are PNP-DTA124EK with internal resistor of R1 (22 ohm) and R2 (22 OHM). The NPN type part number is DTC144EK with internal resistor of R1 (47 ohm) and R2 (47 ohm). Another number for NPN is DTC124EK with internal resistor of R1 (22 ohm) and R2 (22 ohm).
Testing surface mounted transistor
If the surface mount transistor do not have any internal resistor in it (which is very rare) then you can check the transistor the same way you checka bipolar transistor. An analog multimeter will do a great job in measuring transistor. However, if the surface mounted transistor consists of internal resistor just like the digital transistors, there is no way you can check it. This is due to the 'extra' resistance when measuring the transistor. Thus the reading that you get will not be accurate. The only way to test it is to swap another similar transistor with the same part number. After many years in electronic repairing line, i found that digital transistors are very reliable compare to the surface mounted type. Not only the surface mounted transistor are small, the part number sometimes are hard to recognize even with a magnifying glass. One more weakness about the surface mount transistor is that it can burnt easily when excessive current passed thru it. This will even make your repair work difficult as you could not see the part number. Even with the help of surface mount transistor cross there is no way to identify the component unless you have the similar model of the equipment with you.
posted by Jestine Yong at 6:54 AM
0 Comments:
Post a Comment
<< Home