Because all the windings of the transformer are on the same pair of magnetic cores! So as long as there is a group of green lights, it proves that the whole transformer is not short-circuited! It is not necessary to test each group. When you repair the power supply part and repeatedly damage it after replacement, the switch tube burst as soon as the power is turned on. Don't worry, of course, the maintenance expert has experience, it is not a problem, but the long-term use of this tester can bring you high efficiency when repairing the power supply. Save working time! You should first test whether the switching transformer is short-circuited between turns. The test is very simple! Connect the instrument to the 5v power supply, and the tester has been upgraded to use the USB interface of the 5v charger for Android phones, so this test The instrument is not equipped with a power supply when it is sold. The customer should prepare it by himself. Please be aware that the two fish plagues are connected to the winding ends of the transformer coil with a large number of turns. Note, this tester can only test high-frequency with magnetic cores! It can also test step-up with magnetic cores, and can not test power frequency with steel sheets! It can also be tested online, (but the power board is not live! It can be reflected Check whether the output load of the transformer is normal or there is a short circuit., Weight: 0.09700339528 pounds, Manufacturer: ximie