PSU for SE & SE/30 trips breaker on 240VAC?

JDW

Administrator
Staff member
Founder
Sep 2, 2021
2,374
1,901
113
54
Japan
youtube.com
I received a question from a YouTube viewer about his recapped PSU for the SE & SE/30. He said that he tried to test the output voltages in the NO LOAD condition (disconnected from the Mac), and it trips his breaker every time he flips on the power switch. He said when the PSU is connected to the motherboard though, it doesn't trip the breaker at all.

I don't live in a 240VAC country but some of you folks do. Do any of you have experience testing a PSU in the NO LOAD condition? Is it the same for you?

@Kai Robinson
 

Kai Robinson

TinkerDifferent Board President 2023
Staff member
Founder
Sep 2, 2021
1,307
1
1,298
113
43
Worthing, UK
That's not good - plenty of SE power ups that didn't trip the electrics... Something tells me that the inrush current limiter is maybe faulty?
 
  • Like
Reactions: JDW

muse

New Tinkerer
Nov 3, 2025
6
4
3
I'm the one with this problem, thanks to JDW for relaying my question from YT.

To further isolate the fault, I disconnected the power supply board from the mains input and removed it, while leaving the IEC inlet, line filter choke, and power switch intact within the chassis with breaker still tripping under this config.

So what I have is just the IEC mains connector, choke and power switch which rules out the PSU board.

I didn't want to keep messing around as I'm not experienced enough given the potential dangers. So I re-assembled the unit and it seems to work inside the Mac.
 
Last edited:
  • Like
Reactions: JDW

JDW

Administrator
Staff member
Founder
Sep 2, 2021
2,374
1,901
113
54
Japan
youtube.com
Well, I'm not sure what the exact problem is, but thank you for joining us here on TinkerDifferent. I hope you enjoy the forum!