Welcome to MacTalk Australia

the largest Australian community for Apple discussions and topics

Join the discussions, Register Now!
Results 1 to 8 of 8
  1. #1

    Join Date
    Apr 2004
    Posts
    336

    Default Possible blown fuse in G4 power supply

    Hi,

    I'm pretty sure I've blown the power supply fuse in my Power Mac G4 466Mhz Digital Audio. The machine won't start up at all. Does anyone have a guide on how to replace the fuse and which fuse I need to buy?

    Thanks

    Jed

  2. #2

    Join Date
    Oct 2005
    Location
    Wollongong
    Posts
    1,053

    Default

    If it is anything like the other PSUs I have opened, you remove the top case of the PSU (after you have unplugged it from the wall of course!) and the fuse should be pretty apparent. It should have markings on the ends that indicate the rating. Just be careful though, unless you had a power surge that blew it, the fuse going is likely to be just an indicator that something further down the line drawing too much current. If that is the case, the replaced fuse will most likely blow too.
    Good luck!
    - Berwyck
    Macs: MBP 13" C2D 2.23GHz

  3. #3
    Byrd's Avatar Byrd is offline Moderator

    Join Date
    Jan 2004
    Location
    Melbourne
    Posts
    6,825

    Default

    Depends on how the power supply "blew". Don't bother if it let out magic smoke or died spontaneously. If there was a surge, then yes perhaps it could be fixed by replacing the fuse. Please be careful going inside the PSU - don't touch anything else and leave it off for a couple of days, ideally, before delving in!

    You can also use a standard ATX power supply fairly easily (with some modification).

    JB

  4. #4
    mmulhern's Avatar mmulhern is offline Classic!

    Join Date
    Nov 2006
    Location
    Sydney
    Posts
    1,223

    Default

    Quote Originally Posted by Byrd View Post
    Depends on how the power supply "blew". Don't bother if it let out magic smoke or died spontaneously. If there was a surge, then yes perhaps it could be fixed by replacing the fuse. Please be careful going inside the PSU - don't touch anything else and leave it off for a couple of days, ideally, before delving in!
    I concur, the last PC power supply I was asked to look at that "blew a fuse" had actually blown the capacitors. Ask them the noise it made, if it was a loud bang (with smoke) I'd go straight to replace, rather than repair.

    If you are adventurous, the following link is for a DIY ATX->MDD power supply mod for "inspiration".

    Power Mac G4 (MDD) ATX Power Supply conversion | Applefritter

    but you'll probably be better off picking up another machine with matching PS and replace it.

  5. #5

    Join Date
    Apr 2004
    Posts
    336

    Default

    Quote Originally Posted by Byrd View Post
    Depends on how the power supply "blew". Don't bother if it let out magic smoke or died spontaneously. If there was a surge, then yes perhaps it could be fixed by replacing the fuse. Please be careful going inside the PSU - don't touch anything else and leave it off for a couple of days, ideally, before delving in!

    You can also use a standard ATX power supply fairly easily (with some modification).

    JB
    It blew when I (foolishly) flicked the red switch on the back of the machine while it was plugged in. The computer was not turning on at all so I decided to flick it up and down :/ There was no loud bang, but a little bit of smoke.

  6. #6
    Byrd's Avatar Byrd is offline Moderator

    Join Date
    Jan 2004
    Location
    Melbourne
    Posts
    6,825

    Default

    I'd say you're royally stuffed Jed - it's not coming back to life, sorry to say Have a quick look, if that fuse looks totally mangled forget it.

    JB

  7. #7

    Join Date
    Apr 2004
    Posts
    336

    Default

    Quote Originally Posted by Byrd View Post
    I'd say you're royally stuffed Jed - it's not coming back to life, sorry to say Have a quick look, if that fuse looks totally mangled forget it.

    JB
    Damn :/ Ah well, it wasn't like I had any use for the machine anyway

  8. #8

    Join Date
    Aug 2009
    Posts
    340

    Default

    The switch on the back is probably 110v to 240v. I don't have one to look at but I am guessing so.. if the machine wasn't powered on, there is a good chance it has blown the protection device... a varistor which is designed to protect it as well as the fuse. But you need to take it to a specialist repairer or at least somebody who has a clue or 3. Switch mode power supplies, once they blow one device can simply blow everything you replace when you turn it back on due to missing one little item.

    Just so you know what it has done... the bridge rectifier in the power supply was swapped to voltage doubler... that means the 240v AC mains in Australia which is rectified to around 350V dc was voltage doubled to around 650v. Depending on how fast the varistor blew everything has been subjected to way over tolerance... but I have recovered power supplies where people had been foolish enough to do that red switch swapping... but long ago before they cost $40 for a new one.

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •