Antec AR300 psu, loud squeal, no power

[need_info]

Re: Antec AR300 psu, loud squeal, no power

Mo, Some thoughts on your schematic. R34 is R34; 4.99K. C19 measures 100nF. The unmarked diode is a Schottky SB540, D10. L2 measures 5.1uH. To me it looks like ZD3 does not connect to ground but to where R25/EC3 connect to the transformer. It measures 2.9V (not sure of this yet).
Jon

[need_info]

Re: Antec AR300 psu, loud squeal, no power

I finally got the PS powered on and measured ZD3, it did measure 10V. So my earlier post was incorrect in this regard.

[momaka]

Re: Antec AR300 psu, loud squeal, no power

Mo, Some thoughts on your schematic. R34 is R34; 4.99K. C19 measures 100nF. The unmarked diode is a Schottky SB540, D10. L2 measures 5.1uH. To me it looks like ZD3 does not connect to ground but to where R25/EC3 connect to the transformer. It measures 2.9V (not sure of this yet).
Jon

Cool.
Thanks for double-checking these. I updated the schematic and attaching it below. Does ZD3 and R71 look to be correctly connected now (that is, one side to primary ground / negative lead of big bulk cap?) At least going by your description and what I've seen before, it makes much more sense for ZD3 to be connected this way... though the only reason why I originally drew it where it was on the previous schematic was because that's all I could see from the provided pictures. And yes, 10V for ZD3 seems a lot more like it than 2.9V. The idea behind ZD3 is to protect U3 E-C junction from overvoltage... and I'm sure even a higher-rated voltage Zener will probably work fine here, so long as it's rated less than the V_ceo voltage of U3.

Updated schematic: