What's the problem with hiccups after switching power on
Fault phenomenon: After the switching power supply is powered on, there is a hiccup sound, and the output DC voltage of each channel is extremely low and unstable.
Troubleshooting: start from the load circuit first, no damaged components. Later, it is necessary to check the voltage absorption network connected in parallel with the N1 winding, and I feel that there is no abnormality. Take the vibration board and replace the vibration chip and peripheral circuits. The problem still exists after power-on. There is no problem in checking the vibration and voltage regulation links, and there is no abnormality in the load circuit after rechecking. Troubleshooting.
Whether the switching transformer is broken, first rule out this possibility.
Directly connect DC18V to pins 7 and 5 of 3844, and connect DC100V to the DC530V power input end of the switching power supply. After power-on, the circuit starts to vibrate. In an instant, the Z101 in the circuit starts to emit smoke. Observe that this circuit is a compound voltage absorption circuit. There is a resistance-capacitance absorption circuit in parallel at both ends of Z101. After temporarily removing Z101, measure the DC output voltage of each channel. ).
Find the cause of the failure, replace Z101 with three 100V voltage regulator tubes in series, power on the test machine, and the switching power supply operation returns to normal
