How to Test Damped Horizontal Output Transistors with a Multimeter
The output transistor with damping has a base, collector, and emitter transistor, as well as NPN and PNP types. So, how to use a faster method to measure the transistor to confirm its pin and type. Additionally, can the working state of the transistor be determined through transistor measurement?
Generally, a multimeter is used to detect output transistors with damping. So, how to use a multimeter to detect output transistors with damping? What are the detailed testing methods, steps, and principles included?
Place the multimeter in the R × 1 position and measure the resistance between the electrodes of the output transistor with damping separately to determine if it is normal.
Connect the red probe to E and the black probe to B. At this point, it is equivalent to measuring the resistance of the equivalent diode of the high-power transistor B-E junction and the protection resistor R in parallel. Since the forward resistance of the equivalent diode is small, and the resistance of the protection resistor R is generally only 20-50, the resistance of the two in parallel is also small; On the contrary, by swapping the probes, that is, connecting the red probe to B and the black probe to E, the measured value is the parallel resistance between the reverse resistance of the equivalent diode of the high-power transistor B-E junction and the protection resistor R. Due to the large reverse resistance value of the equivalent diode, the measured resistance value at this time is the value of the protection resistor R, which is still relatively small.
Connect the red probe to C and the black probe to B. At this point, it is equivalent to measuring the forward resistance of the equivalent diode at the B-C junction of the high-power transistor inside the tube. Generally, the measured resistance value is also relatively small; Swap the red and black probes, that is, connect the red probe to B and the black probe to C, which is equivalent to measuring the reverse resistance of the equivalent diode of the high-power transistor B-C junction inside the tube. The measured resistance value is usually infinite.
Connect the red probe to E and the black probe to C, which is equivalent to measuring the reverse resistance of the damping diode inside the tube. The measured resistance value is generally large, about 300~∞; Swap the red and black probes, that is, connect the red probe to C and the black probe to E, which is equivalent to measuring the forward resistance of the damping diode inside the tube. The measured resistance value is generally small, about several to tens.
