Resolved Macintosh Plus overloads the power breaker

Discussion in 'Apple Collectors' started by Enric, Dec 29, 2015.

  1. Enric macrumors newbie

    Joined:
    Jul 30, 2013
    Location:
    Geneva, Switzerland
    #1
    Hello,

    I have a nice Mac Plus supplied with a Radius Accelerator 16. It boots fine and display a stable image. Everything seems ok, but after a few minutes the circuit breaker shut down the power in the room. Once the circuit breaker reset, the Mac boots fine again and the process is repeated.
    Any idea on what to investigate ?
     
  2. Gav2k macrumors G3

    Gav2k

    Joined:
    Jul 24, 2009
    #2
    Have you tried moving it to another room on a different breaker ?
     
  3. Enric thread starter macrumors newbie

    Joined:
    Jul 30, 2013
    Location:
    Geneva, Switzerland
  4. havokalien macrumors 6502a

    havokalien

    Joined:
    Apr 27, 2006
    Location:
    Kelso, Wa
  5. MacTech68, Dec 29, 2015
    Last edited: Feb 9, 2016

    MacTech68 macrumors 68000

    MacTech68

    Joined:
    Mar 16, 2008
    Location:
    Australia, Perth
    #5
    You might want to try the Class X 0.1uF capacitor. It's C38 on a 120v board. Also there are two Class Y 4700pf capacitors at C33 and C37.

    However, if you have a 230volt board, the Class X 0.47Uf is at C37 and the two Class Y 4700pf capacitors at C33 and C36.

    IMPORTANT NOTE - These capacitors must be the appropriate "Class" for their purpose. "Class X" must be replaced by "Class X" and "Class Y" must be replaced by "Class Y".

    The originals may be termed as "self - healing" but at this age, many are beginning to reach the end of their workable life, causing momentary shorts across the mains input.

    Class Y are supposed to 'fail safely' (since they are designed for line to chassis) but who knows what happens when they reach their end of life as they age. Class X will short across the line and can cause fast breakers to trip.

    When purchasing, I would HIGHLY recommend getting them from a reputable dealer and not from cheap ebay sellers. These are a safety rated component for good reason. Also, you'll be looking for Class "X2" or "Y2" - the most common for household electronics filtering.

    Both should be rated at 250Volts AC or 275 Volts AC, and will be marked with all sorts of safety & compliance bodies.

    LATE EDIT - Make sure to get ones that have the correct lead spacing and size for the board.

    Analog 110v ClassX & Y.jpg

    Analog 230v ClassX & Y.jpg
     
  6. Enric thread starter macrumors newbie

    Joined:
    Jul 30, 2013
    Location:
    Geneva, Switzerland
    #6
    Thanks! Just ordered the three caps, hope to be back with good news in a few days...
     
  7. MacTech68 macrumors 68000

    MacTech68

    Joined:
    Mar 16, 2008
    Location:
    Australia, Perth
    #7
    Just remembered that if you're getting the potted type (which is most common) you'd need to check the spacing of the center of the solder pads since they come in fixed lead spacings. Sorry to mention that now that you've already ordered them. :(

    Hopefully you already took that into account.
     
  8. Enric thread starter macrumors newbie

    Joined:
    Jul 30, 2013
    Location:
    Geneva, Switzerland
  9. Enric thread starter macrumors newbie

    Joined:
    Jul 30, 2013
    Location:
    Geneva, Switzerland
    #9
    So, worked perfectly, the mac is powered for more that one hour now. Thanks so much!

    The 0.47uf was a bit tricky to set in place because its body is slightly larger than the original one. But this was overall a straightforward job!
    The two 4700pf are of both X and Y class (I ordered them as Y2 caps, but it is both mentionned 250-Y2 and 300-X1 on their body)

    Now I am wondering how long the remaining old caps will last...


    IMAG0195.jpg
     
  10. MacTech68 macrumors 68000

    MacTech68

    Joined:
    Mar 16, 2008
    Location:
    Australia, Perth
    #10
    The Y2 caps can be "Y2/X1" combined - the main concern is that they are rated Class Y since they are fitted AC Line to Chassis.

    As for the other Caps, some say "replace them all". However, if you're not seeing any other problems right now, You could leave it at that.

    If you decide to replace them all, usually it's only the Electrolytics that need replacing. However, there is one that should be replaced using a Metalized Polyester cap - Some boards already have this done, depending on how recently the board was exchanged via Apple. It's one of the two large caps on the top edge of the board.
     

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