Multimeter measurement ballast good or bad method
Multimeter can only measure the good and bad of the inductive ballast, use the multimeter resistance gear test, general pass is considered normal. The multimeter to the ohm file, with two probes to test the ballast terminals, there is a certain resistance is good. The size of the resistance and the power of fluorescent lamps, such as 40W of the normal ballast about 50 to 60Ω, if the inductive bad resistance is not certain, may be very large or very small, especially inter-turn short circuit is very difficult to judge, so only a rough reference!
If it is an electronic ballast, not disassembled can not be carefully measured using a multimeter. Under the condition of not disassembled, the multimeter resistance file to measure the four lines connected to the lamp, any two lines can not be presented between the state of bi-directional conduction, otherwise it is the internal resonance capacitance breakdown, that is, the ballast is bad, and other cases to be measured one by one components.
There is a way in the charged without the lamp, the use of a multimeter to measure the electronic ballast in the first two transistor pins, that is, the measurement of the two transistors in the middle of a pin, one of the transistors in the middle of the pin to the ground (that is, the negative level) is about 300 volts, and the other transistor in the middle of the pin to the ground is about 90 volts, if the data is that this electronic ballast is basically a good, charged to measure! Of course, pay attention to safety, do not get a short circuit. Then in the non-electrical without lamps, measuring the electronic ballast to the lamp end of the four lead wires, any number 1, 2, 3 and 4 lead wires, measuring 1 to 2, 3 and 4 can not have a short circuit between 2, 3 and 4 can not have a short circuit (that is, zero resistance). If there is a short circuit can follow the short line check, if one of the capacitor is bad, the bad capacitor will be replaced even if it is repaired, electronic ballast output is a high-frequency electricity, multimeter is not good to check the conditions can be measured with an oscilloscope.
You can use a 40W incandescent bulb and ballast in series connected to the power supply, a good ballast light dimming but will not go out. Electricians basically change the lamp, and then change the ballast, the replacement method is actually the quickest means of repairing these things.
