The picture shows a simple linear power supply concept I found in an old product. The AC input range is 70 ~ 150 VAC from mains (nominal 115 VAC). R2 is a metal film resistor. C2 is ceramic capacitor (Digi-key part). The transformer is this one 14A-10R-20. The V_UNREG output feeds this switching regulator. I'm trying to simulate this circuit with LTspice coupling 4 inductors to get the transformer. The input AC source waveform is ok, but the voltage at C2 is practically zero. Why could this happen? In the real world this design should have some flaws though. R2 goes open circuit. The transformer also gets warm. Some thoughts I have are the circuit not good handling surges. Like, a surge may damage R2 and C2 easily. I don't see the MOV activates though. Also, what's the real purpose of R2/C2? Values don't look reasonable if the intent was a low pass filter. Any circuit analysis thoughts are welcome.