cupoftea
Advanced Member level 6
Due to space constraints, I had to put the NTC further "downstream" from the mains input connector
than the common mode choke. So NTC is actually right by the 400V post rectifier electrolytic cap.
But I wanted to actually connect the NTC "upstream" of the input X2 capacitor. Because then the NTC
offers some mains transient protection to the X2 capacitor, meaning the PSU will likely last longer.
So I indeed connected the NTC "upstream" of the X2 capacitor, and to do so, the Line input then goes
wandering off up the PCB, past the common mode choke, and obviously the PCB track out of this NTC then
comes all the way back to the input, again passing the Common mode choke. As such, unfortunately,
any common mode noise could now simply avoid the common mode choke and "bypass" it via the described connections.
Would you agree that a good mitigation for this would be to add another small, very high frequency common mode choke near the mains input connector? (we may just be able to find room there for a small one)
than the common mode choke. So NTC is actually right by the 400V post rectifier electrolytic cap.
But I wanted to actually connect the NTC "upstream" of the input X2 capacitor. Because then the NTC
offers some mains transient protection to the X2 capacitor, meaning the PSU will likely last longer.
So I indeed connected the NTC "upstream" of the X2 capacitor, and to do so, the Line input then goes
wandering off up the PCB, past the common mode choke, and obviously the PCB track out of this NTC then
comes all the way back to the input, again passing the Common mode choke. As such, unfortunately,
any common mode noise could now simply avoid the common mode choke and "bypass" it via the described connections.
Would you agree that a good mitigation for this would be to add another small, very high frequency common mode choke near the mains input connector? (we may just be able to find room there for a small one)
