Macintosh SE PSU Diode

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Level 4

1,844 points

Macintosh SE PSU Diode

Hello (Again)!

Yesterday I posted regarding my recently acquired Macintosh SE. I was using it today, and I left it on for a few minutes to go to something else, and when I came back, the screen was off and it was just making a repetitive noise in the speaker. After some research, I came across this. It seems to be my problem exactly. After opening the computer for the second time, I was very intimidated. I don't have the proper tools to discharge the CRT so I did the obvious thing and worked around it 😀. After 15 minutes of trying not to fry myself, I have removed the floppy drive, hard drive, logic board, and power supply. Now that I have the power supply out, how do I discharge it? Also, I don't have a friend that can help me with the diode issue, so I am going to have to deal with it myself. (And I don't know anything about it.) Am I out of luck, or is this doable. It seems more difficult/less clean in the end to just use a modern ATX PSU. Thank you!

Macintosh SE20-OTHER, Other OS

Posted on Jul 25, 2018 6:45 PM

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Answer 1

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Jan Hedlund

Level 7

22,201 points

Jul 26, 2018 1:46 PM in response to Danny Dorazio

As you already know, all work inside a compact Mac like the SE can be very dangerous because of the high voltages involved, and should be performed by qualified personnel only. Charges can remain for a long time when the computer has been switched off and disconnected from the mains.

Normally, a faulty power supply unit is removed and replaced. The problem here is that old replacement units may be as bad as the one that is going to be replaced. Mains/line voltage levels are very dangerous. Charges in (especially large) capacitors can be very dangerous. If at all, this is work for specialists. Attempting to carry out repairs without knowing exactly what to do is not wise. I would strongly advise you to ask someone with the proper expertise for help. Do not carry on on your own. In order to learn more, you may want to look for Larry Pina's book Mac Classic & SE Repair and Upgrade Secrets (ISBN 1-566609-022-9).

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