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Understanding Monitor flyback transformer pins

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 Monitor and television flyback transformer have some similarity except only on the internal capacitor. Monitor flyback transformer have the internal capacitor to improve the picture quality. Without the internal capacitor the display will bend or slightly out of shape especially at both the right and left hand side of the picture. Most flyback transformer will have ten pins at the bottom of the flyback. Each pin serve a purpose or function as part of a complete circuit. The common pins that you can find in monitor flyback are:
B+, H. collector pulse, ABL, GROUND, G1, AFC, VCC, HEATER and X-RAY PROTECT.
B+ and horizontal collector pulse forms one winding which we call it as flyback primary winding. This is the most important winding and easily develop a short circuit when B+ line or Horizontal output transistor have problem. Sometimes a shorted internal capacitor in the flyback may cause the primary winding to burn internally. The only way to test it is to use a flyback or lopt tester. Normal multimeter can't check this kind of problem.

Next is the ground,G1, and AFC winding. AFC stand for automatic frequency control and it send signal from the flyback to the horizontal oscillator ic to lock or synchronize the frequency of the monitor. If this afc line have problem the display will shift either to the far left or far right. There is no way you can adjust the picture to the center. The function of G1 is to pull the electron generated from the cathode and channel it to G2 which is the screen voltage. G1 normally is negative voltage. If there is a missing G1 voltage to the picture tube the monitor display will become very bright with flyback lines across the screen and sometimes the monitor will goes into shutdown mode.
 

 


ABL stand for automatic blanking limiter- I refer it as contrast circuit. Why? because whenever there is a
contrast problem i will look for this pin and begin to trace from there. Normally a high ohm resistor and a shorted ceramic capacitor caused the display to become dim and you think it might be the fault of a defective picture tube. Heater pin nowadays hardly found in monitor flyback because the crt heater voltage derived from the switch mode power supply. Heater pin still can be found in television flyback. If the anode voltage is too high, x-ray protect pin will send a signal to horizontal oscillator ic to disable the horizontal drive waveform. Without drive waveform the high voltage will collapsed and protect the user from excessive x-ray generated by the abnormal high voltage. The flyback transformer will also generate high pulse ac which later convert to dc voltage as a supply  voltage to certain circuit such as the vertical circuit. If you truly understand how a flyback transformer work and the functions of each pin, troubleshooting  monitor or tv will be much easier.