Hi everyone!
Troubleshooting SMPS with output voltage fluctuation from 4.8V to 5.0V, spikes to 5.2V and back to 4.8 every 2-3 seconds.
Replaced with brand new: both optocouplers U6501/02, rectifier D6515, U6503 IC.
Primary voltage is stable 160V on C6506.
T6501 secondary side is stable AC voltage.
Diodes tested OK. Caps OK. Resistors OK.
Suspect D6524, but not sure....🙁
Any help is greatly appreciated!
Troubleshooting SMPS with output voltage fluctuation from 4.8V to 5.0V, spikes to 5.2V and back to 4.8 every 2-3 seconds.
Replaced with brand new: both optocouplers U6501/02, rectifier D6515, U6503 IC.
Primary voltage is stable 160V on C6506.
T6501 secondary side is stable AC voltage.
Diodes tested OK. Caps OK. Resistors OK.
Suspect D6524, but not sure....🙁
Any help is greatly appreciated!
Last edited:
The output is stable? Only VSB is fluctuating?
Some SMPS use a power FET to generate VSB.
That circuit is separate from main circuit, used to start the supply.
Can be a pain, generally a resistor and small capacitor are there, and maybe a TL431, change it if needed.
Did not check out your pdf file...
Some SMPS use a power FET to generate VSB.
That circuit is separate from main circuit, used to start the supply.
Can be a pain, generally a resistor and small capacitor are there, and maybe a TL431, change it if needed.
Did not check out your pdf file...
