CSS- Week 8 - TEC.pptx quarter exam quarter exam
- 1. Testing Electronic Components Competencies •LO 3. Testing of Components (TLE_IACSS9-12TEC-IVf-h-26), •LO 4. Evaluate the Testing Process (TLE_IACSS9-12TEC-IVh-j-27)
- 2. A digital multimeter is a test tool used to measure two or more electrical values— principally voltage (volts), current (amps) and resistance (ohms). It is a standard diagnostic tool for technicians in the electrical/electronic industries. MULTITESTER
- 3. Meter Scale Name Plate Needle Collector Alternating Current Voltage Block Ranging Selector Positive Test Prod Negative Test Prod Needle Pointer Direct Current Voltage Block Resistance Block Direct Current Mille Ampere Block 0 ohm Adjustment Knob
- 4. •Meter Scale – shows the calibration of Ohms, Volts and Ampere •Name Plate - shows the brand name and model of the multi-tester •Needle Corrector - used to adjust the needle pointer to rest to zero when not in used
- 5. •Positive test Prod - the red test pointer •Negative test Prod - the black test pointer •Alternating Current (AC) Voltage Selection Range - ranges used or setting when measuring the AC Voltage •Direct Current (DC) Voltage Selection Range - ranges used or setting when measuring the DC voltage
- 6. •0 ohm Adjustment Knob- used to set to zero the needle pointer by shorting the two test prods before measuring the resistance •Needle Pointer - points to the number in the meter scale that indicates the reading
- 7. •Ohmmeter Range -ranges used or setting when measuring the resistance •DC milli-Ammeter Range -selection ranges when measuring small amount of direct current
- 9. A resistor is an electrical component that limits or regulates the flow of electrical current in an electronic circuit. Resistors can also be used to provide a specific voltage for an active device such as a transistor.
- 10. How to Test Resistors
- 11. Resistance Measured? Resistance is measured in ohms, symbolized by the Greek letter omega ( ). Ohms are named after Ω Georg Simon Ohm (1784-1854), a German physicist who studied the relationship between voltage, current and resistance. He is credited for formulating Ohm's Law.
- 12. How is Resistance Measured? Resistance is measured with an Ohmmeter. When using an analog multi-tester, after setting it to desired range it must be 0Ω adjusted to obtain an accurate measurement. Proper way of measuring resistance is shown.
- 13. Suppose you are testing a 100 ±5% resistor Ω (based on its color code). How would you conclude that it’s good or defective? Since this resistor has 5% tolerance, it is expected that measurement reading will fall between 95 to Ω 105 to consider it good. Otherwise it is Ω defective and needs to be replaced.
- 14. How is Resistance Measured?
- 16. A capacitor is a passive electronic component that stores energy in the form of an electrostatic field. In its simplest form, a capacitor consists of two conducting plates separated by an insulating material called the dielectric.
- 18. A faulty capacitor may have one of three basic problems: 1. A short, which is easy to detect and is caused by contact from plate to plate. 2. An open, which is again quite easy to detect and is normally caused by one of the leads becoming disconnected from its respective plate.
- 19. 3. A leaky dielectric or capacitor breakdown, which is quite difficult to detect, as it may only short at a certain voltage. This problem is usually caused by the deterioration of the dielectric. The capacitor with this type of problem is referred to as a leaky capacitor
- 20. Different Types of Capacitor
- 21. Proper way of checking a capacitor of 47µF and larger with an analog ohmmeter by using the procedure is shown below.
- 22. Step 1: Ensure that the capacitor is discharge by shorting the leads together.
- 23. Step 2: Set the ohmmeter switch to X10 range
- 24. Step 3: Connect the test prods to the capacitor. The needle pointer will deflect rapidly to 0 ohms initially.
- 25. Step 4: While the test prod is steady connected to the capacitor leads, the needle pointer should then return to infinity as the capacitor charges
- 26. TRANSFORMER
- 27. A transformer is a device with primary and secondary windings. It will transfer power from the primary windings to the secondary windings through induction. An open in the primary winding will prevent any primary current, and therefore there will be no induced voltage in the secondary and therefore no voltage will be present across the load. TRANSFORMER
- 28. An open secondary winding will prevent the flow of secondary current, and once again, no voltage will be present across the load. A partial or complete short in the primary or secondary winding of transformer will result in an excessive source current that will probably resulted to overheating and burn of transformer.
- 29. An ohmmeter can be used to test for partial or complete shorts in transformer windings as shown below.
- 30. An ohmmeter can be used to test for partial or complete shorts in transformer windings as shown below.
- 31. HOW TO TEST TRANSFORMER?
- 32. WHAT IS DIODE?
- 33. Diodes can be used as rectifiers, signal limiters, voltage regulators, switches, signal modulators, signal mixers, signal demodulators, and oscillators. The fundamental property of a diode is its tendency to conduct electric current in only one direction.
- 34. Diodes are semi-conductor device which is used to convert alternating current (AC) to direct current (DC). The two electrodes or terminals of the diode are called Anode and Cathode.
- 35. An ohmmeter can be used to check whether a diode has malfunctioned or is operating correctly. A good diode should display a very low resistance when it is biased ON (forward biased), and a very high resistance when it is biased OFF (reverse biased).
- 36. A good diode must conform to these two conditions, otherwise it is considered defective and needs to be replaced. The three possible defects occurred in diodes are; open (shows very high resistance on forward testing), shorted (shows low resistance on reverse testing) and leaky (shows small amount of resistance when reverse tested).
- 37. Rectifier Diode
- 38. Signal Diode
- 40. HOW TO TEST DIODE?
- 42. Transistor is a semi- conductor component basically used as switching or amplifying signal. It has two types; the NPN and PNP and with three leads called the base, collector and emitter.
- 43. These failures are normally the result of excessive temperature, current, or mechanical abuse and generally result in one of three problems: 1. An open between two or three of the transistor’s leads 2. A short between two or three of the transistor’s leads 3. A change in the transistor’s characteristics
- 44. If the transistor tester is not available, the ohmmeter can be used to detect open and shorted junctions, which are the most common transistor failures. Figure below shows the step by step procedure for testing an NPN transistor.
- 45. a. Forward test of base – emitter junction of transistor shows low resistance
- 46. b. Forward test of base – collector junction of transistor shows low resistance
- 47. c. Junction test of emitter – collector of transistor shows high or infinite resistance
- 48. HOW TO TEST TRANSISTOR ?