Compared to switch mode power supplies, linear power supply troubleshooting was a breeze (SMPS). The primary side of a linear transformer receives AC voltage, which is subsequently transformed by the secondary winding into a lower or higher AC voltage.
A
diode and capacitors rectify and filter the output AC voltage, resulting in a
pure DC voltage. Identifying the source of the problem in a linear transformer
circuit is a cinch. With a switch mode high voltage low current power supply,
things are a little different.
The
switch mode power supply has a different operating principle than the linear
kind. Large capacitors are used to filter the DC output of the bridge rectifier
(full wave rectifier), which generates an uneven DC output (usually 220 micro
farad and up to 450 volts).
Transistor
primary winding magnetic field changes are caused by the PWM IC, which outputs
a signal to operate the transistor (or FET) after receiving the voltage.
Voltage is generated in the secondary windings as a result of the changing
magnetic field. It is then rectified, filtered and controlled to generate clean
DC voltage supplies from the secondary windings. B+ is one of the most
important DC output voltages for flyback transformers (for TV and Monitor
Circuit)