Don't go replacing components until you have an idea of where the fault could be. It could just destroy new parts if there is some other severe problem.
I'm aware of this. The total cost was far below 1$, so I thought I'll give it a shot and save some time. Sadly, no luck.
By no voltage do you mean no output or no input?
Both. The input voltage seems to be pulsing (auto-range indicator on my meter is pulsing ~ once pew two seconds). The voltage on the BP pin of LNK304PN is 5.8V, but the FB pin stays low (on DC range). There is some waveform of frequency of several kHz (multimeter readout), but I cannot tell more without a scope.
Between D and S pins of LNK304PN I have 320V DC. Between BP and S: 5.8V. Between FB and S: ~0.06V, changing.
P.S. You can check an inductor as it should read short or low ohms if working.
The inductor reads 1.6 ohms (in circuit).
If there is no input check everything in the path from the rectifier to the regulator, there may be some transistors switching the input voltage that blew.
AFAIK the switching transistors are integrated in the LNK304PN.
Also check for shorts across the pins.
All S pins shorted, but they should be. But there is 8.4 ohms between common and input of the voltage regulator, measured on the PCB, with the regulator removed. It's rather strange, isn't it?
I do not fully understand the operation of LNK304PN. Should I expect any constant voltage on the FB pin? I guess not - I'm trying to reverse the power section, so far it seems very alike to the application note from page 4/5.
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