Hello again!

I am still working on reducing the EMI noise issues on our latest design implimenting the TNY280 device. I have some pretty good information as far as calculating snubbers for the output diode and primary ringing. However, I have a lower-frequency ringing around 511Khz that appears to be happening during skipped cycles. I am not sure if the cause is the resonant freqency of the transformer itself, or if it has something to do with the LC combination after the output diode. Any information you can shed on this would be helpful. I have attached a jpg of the waveform. Thanks.