I built this 10W flyback. See schematic.
It was working perfectly for several days of testing then I powered it up and it stopped regulating the duty cycle remains locked at a little over 4% the outputs are at about ten percent of there regulated values.
I noticed my once nice and clean DCM waveform over my current sense resistor (R4_D) is now oscillating at about 1.5MHz.
Scope shot current sense resistor (R4_D) 10mV/div.
I suspected the overcurrent protection may be kicking in but there is no indication of this. If the OCP is active the SS pin should be ramping up and down trying a restart but this isn't happening.
The controller is the TPS40210.
I'm down to switching out the controller, unless someone can offer an explanation.
I'd prefer not to pull the controller out because it would be a bitch without damaging the traces it's a fine pitch 10 pin MSOP-PowerPAD