Macintosh Plus Bang and Smoke

Discussion in 'Apple Collectors' started by mikemike690, Feb 9, 2016.

  1. mikemike690 macrumors regular

    mikemike690

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    #1
    I just brought a Macintosh Plus, took it apart to see the corrosion, with no damage luckily, and I decided to take the risk to start it up, anyway plugged it in and booted a disk and everything was fine, then after a couple seconds I hear quite a loud bang and smoke coming out of it. Does anyone know what causes this and how to fix it? Thanks.
     
  2. MacTech68 macrumors 68000

    MacTech68

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    #2
  3. mikemike690 thread starter macrumors regular

    mikemike690

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    #3
  4. nightcap965 macrumors 6502a

    nightcap965

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    #4
    It sounds as though the magic smoke has escaped.

    You'll probably find a number of capacitors have leaked. How are your soldering skills?
     
  5. mikemike690 thread starter macrumors regular

    mikemike690

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    #5
  6. MacTech68 macrumors 68000

    MacTech68

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    #6
    Wow. Not seen a Class Y fail - but now I have.

    I's suggest replacing both Class Y 4700 pico farad capacitors. Remember to check the lead spacing.

    Looks like that machine has had a battery leak. What does the other side of the board look like?
     
  7. mikemike690 thread starter macrumors regular

    mikemike690

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    #7
    Yeah it has but nothing really major right? It's just got the corroded contacts. The other side of the board is fine, I'll upload a picture after school. Also what do you mean by the lead spacing? And do you know anywhere I could buy these? Or would I just be able to go to a local electronics shop. Thanks
     
  8. MacTech68 macrumors 68000

    MacTech68

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    #8
    I would advise against buying these on ebay or other auction sites, since these capacitors are very strictly safety rated.

    The lead spacing on this type of component it fixed to a certain width. If you get the wrong lead spacing, you can't fit it into the holes.

    I'll get back to you with a lead spacing.
     
  9. mikemike690 thread starter macrumors regular

    mikemike690

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    #9
    Okay thanks for that
     
  10. MacTech68, Feb 9, 2016
    Last edited: Feb 9, 2016

    MacTech68 macrumors 68000

    MacTech68

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    #10
    For C33 & C36 on the 240Volt International Analog Board, your Y2 capacitors are -

    4700 pico farad <------- THIS IS CRITICAL
    Class Y2 <------- THIS IS CRITICAL
    300Volts AC (or at least 275VAC)
    lead spacing 10.2mm <------- THIS IS CRITICAL Give or take 1mm
    Width 5.1mm
    Length 13.5mm
    Height 10.5mm

    For the Kemet Evox Rifa (the original parts)
    Old Kemet PN P272HL472M300
    New Kemet PN PME271YA4470M

    For C37 on the 240Volt International Analog Board, your X2 capacitor is -

    0.47 micro farad (470 nano farad)
    Class X2 <------- THIS IS CRITICAL
    275Volts AC
    Width 15.3 <------- THIS IS FAIRLY CRITICAL
    Height 22
    Length 30.5 <------- THIS IS FAIRLY CRITICAL
    Lead Spacing 25.4mm <------- THIS IS CRITICAL Give or take 1mm

    New Kemet PN PME271M647K
    Old Kemet PN P276EL474K275


    However, provided you meet the above criteria, you should be fine.

    From your pictures, it looks like the other capacitor C37 may have already been replaced.


    As for where to buy, looking at a few in your location, many don't sell Class X2 or Y2 caps or they only sell Class X2. :(
     

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