I have 2 flyback transformers one is from an old TV and the other one is from an monitor (new).I need to know the negative pin for the HV (high voltage)and the pins from the primary coil (input) and primary coil polarity. Can you tell me a method to find out these things? Thank you
reference 1: The flyback circuit diagram calls for two sets of coils: a primary coil and a feedback coil. The turn ratio is really not that critical so usually ANY two coils in the flyback primary will work. Locate two sets of coils on the horse-shoe-like configured pins by testing the flyback pins for continuity. Often times there are more than two pins connected to a single coil in the transformer. You will need to try the different positions to see which configuration works better for your application. After you have located two independent sets of coils on your flyback, hook them up to the circuit with any polarity. If you turn on the power any you don't hear a whine or hum, try reversing the polarity (switch the leads) of ONE of the coils. If nothing now, reverse the polarity of the other coil. If nothing now, reverse the polarity on the first one you switched again. So the take home message is trial and error. Flybacks can be very picky as to coil polarity because some of them have a rectifier built in them. So try each configuration (8 of them with two sets of coils) until it whines (Occasionally I'll find one that doesn't wine but VERY rarely). Any two sets of coils in a potted flyback should work, so don't try new coils until you're sure you've exhausted all possible combinations. The high voltage will come out of the fat wire from the top of the flyback-usually connected to the CRT with a suction cup. You will not be able to locate the high voltage return pin with a multimeter. The only way to do it is to bring the high voltage line down to the pins and whichever one it arcs like mad to is the one yer looking for. Try to stay away from arcing to any of the pins used for coils. High voltage is not so good for your transistor or power supply. second reference has a lot of useful info plus photos. . .
