superjer2000
Well-known member
I recently purchased an SE/30 and replaced the Sony PSU with a Seasonic. After putting the system back together (recapping and replacing a couple of ICs with legs that were starting to corrode due to cap leakage), I noticed the system wouldn't always turn on reliably - Sometimes after I flipped the switch the system would take ~5 to 10 seconds to turn on and sometimes would turn on and off quickly. I ground the PSU ON lead on the seasonic with the SE/30's power switch (the original switch from the Sony PSU) and based on something I read in the Dead Mac Scrolls (I think it was) the switch on the Sony PSUs can go bad. I tested the switch with my multimeter and sure enough it wasn't working properly.
I disassembled the switch and sure enough, the contacts were badly oxidized and one of the rockers had actually come off its base. I cleaned up everything with some Nutrol and Qtips and reassembled and presto, it works perfectly again. I wanted to share this in case anybody has issues with their Sony switch - it is definitely repairable.
The other item I wanted to share is I added a 10 ohm (10 watt) resistor to the 3.3V line on the Seasonic. I don't think that this is necessary and I haven't done it before, but on one of the Seasonic spec sheets I came across, it notes that the SUB version of the power supply I use needs a load on the 3.3V line where as the SUG version doesn't (but the SUG version doesn't provide enough -12V current). I first tried with a 3.3 ohm resistor but it became too hot to touch (I'd estimate around 60c) even when mounted against the PSU case to act like a heat sink. The 10 ohm resistor only gets up to about 22c and puts a 330ma load on the 3.3v line. I've done a number of these Seasonic retrofits and haven't ever done this before, but I figured it can't hurt.
I disassembled the switch and sure enough, the contacts were badly oxidized and one of the rockers had actually come off its base. I cleaned up everything with some Nutrol and Qtips and reassembled and presto, it works perfectly again. I wanted to share this in case anybody has issues with their Sony switch - it is definitely repairable.
The other item I wanted to share is I added a 10 ohm (10 watt) resistor to the 3.3V line on the Seasonic. I don't think that this is necessary and I haven't done it before, but on one of the Seasonic spec sheets I came across, it notes that the SUB version of the power supply I use needs a load on the 3.3V line where as the SUG version doesn't (but the SUG version doesn't provide enough -12V current). I first tried with a 3.3 ohm resistor but it became too hot to touch (I'd estimate around 60c) even when mounted against the PSU case to act like a heat sink. The 10 ohm resistor only gets up to about 22c and puts a 330ma load on the 3.3v line. I've done a number of these Seasonic retrofits and haven't ever done this before, but I figured it can't hurt.
