Hi:
I've been trying to repair a miniATX power supply that has mentioned chip. The good news is that I have 2 for comparison (one works and the other doesn't).
The faulty one only has a stable 5Vsb (both purple and green wire have 5V). The chip is powered with the standby voltage, however when PSON is grounded, no PWM output goes in OP1 & OP2 pins. Removing Diode output filters and switching transistors doesn't make any difference.
What might be the cause for PWM circuit not switching on?
(It's not the chip).......I've changed between SMPS with same result. (the one that works, still works with a new chip).
I am adding values for all pinout both when it's in standby and switched on (these values belong to the good one). The faulty one has the same values in standby.
Regards,
Francesc.
I've been trying to repair a miniATX power supply that has mentioned chip. The good news is that I have 2 for comparison (one works and the other doesn't).
The faulty one only has a stable 5Vsb (both purple and green wire have 5V). The chip is powered with the standby voltage, however when PSON is grounded, no PWM output goes in OP1 & OP2 pins. Removing Diode output filters and switching transistors doesn't make any difference.
What might be the cause for PWM circuit not switching on?
(It's not the chip).......I've changed between SMPS with same result. (the one that works, still works with a new chip).
I am adding values for all pinout both when it's in standby and switched on (these values belong to the good one). The faulty one has the same values in standby.
Regards,
Francesc.
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