ATX Power Supply Modification 2

All is going to plan for the transplant. I had to do a few things to the supply.

The IEC socket on the old supply used proper X/Y safety caps going from each pole to earth ground while the replacement just had a 1Meg ohm resistor and a 0.33uF X1 suppression cap going to Neutral and Live. I’ve had too many issues in the past with this setup. If the resistor was to short out then the power supply will get cooked to hell. So I just reused the IEC that was on the old supply. If you want to learn about safety caps check out this article from
I also added a ferrite to the AC line from the IEC socket to the circuit board. I did this to help cut out EMI noise since the AC line is rather long. It’s good practice to twist the AC lines together to cut out noise.


Try and keep AC lines away from DC, Signal and Audio lines, 50/60Hz can interfere with assortment of things.

Both fans had bad barrings so I found a high CFM rated fan in my junk box. I have tons of fans and blowers I have kept from stuff I dismantle. While on the hunt for the fan I came across a temperature sensor fan controller and tossed it in. I have the sensor mounted to the heat sink that has the mosfets. So when it’s cool the fan runs at 5V and at around 119 degrees fahrenheit it kicks in full gear to 12V pushing around 100CFM.

After doing a continuity check on the AC line input switch for selecting 115 or 210 I removed the switch and added a jumper wire to the two points since closed was for 115 and open is for 210 on the switch.


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