The primary ramps to over 100V
Obviously, the first and urgently needed "update" would be a complete schematic...I will keep the post updated to let you know how I get on with it.
I keep my point that the waveforms don't fit the claimed transformer ratio and voltages.
Also check if it is mounted in correct direction.
if this is OK, then check if Co1, Co2, and Co3 are high frequency, low esr capacitors. Standard electrolytic don´t work here.
In either case I recommend to add a ceramics capacitor with short and wide wiring to transformer/diode. Use at least 10uF and 50V.
It is common for a snubber to be installed across the primary. The reason it is needed, is that when you switch off supply current, a strong voltage spike is generated by the transformer. (A characteristic of inductors.) Ringing may also be generated.
Ideally the primary flyback voltage should be (Vout+0.5)*N+Vin, which is about 94V. You're showing about 150V. Which happens to be the exact VDD rating of your FET...Why doesn't the primary waveform i posted illustrate the 3.5:1 ratio I stated in post #1?
The schematic says the output caps are rated for 6.3V, you should change them to be 16V or more.The board was working fine when i had it standard with the 3.3V @ 3A, the caps are ceramics and the diode is fine.
Changing the transformer alone won't change the output voltage. Did you adjust the feedback resistors (R13 and R14) to change the setpoint? Is the auxiliary winding still okay with the different transformer?It wasnt until i changed the transformer on the board to output 12V until i had this issue. Hence why ive assumed its something ive done with the transformer rather then anything else.
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?