Mac IIsi power supply stand by fix (Magnetek)

[gonzo]

Hello folks,

this is a success story about a power supply repair (MagneTek 3231-05-001). Maybe it will help somebody else with the same issue.

Recently my Mac IIsi did not power on anymore. I checked the stand by voltage: 0V, nothing. So I opened the power supply

and saw a broken elektrolyte capacitor (400V 10µF) on the high voltage side. This made me wondering because in most cases the low voltage capacitors spit their insides around. I saw that this capacitor was loaded by the diode beside (one way rectifier). I checked, DC only 100V (in Germany we have 230V AC which makes about 300-320V recitified) but 150V AC. The root cause was the rectifier diode that was conductive in both ways. Changed the diode and the capacitor. Everything fine again.

Regards

Florian

 

[bibilit]

Yes, i had the same issue a couple of years ago and replaced the same capacitor.

 

[David Goodson]

I have 2 of these I want to recap. Any tips on opening them? Special rivet removing tool maybe?

 

[PotShotScott]

I had mine partially open today - looks like Philips head screws to me sir

 

[David Goodson]

It’s the Sony one that has screws. The Magnetek one has rivets.

 

[David Goodson]

I finally bought a drill & popped mine open. Were you able to fix this psu by just replacing that one capacitor or does the diode next to it need to be replaced as well?