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Thread: Mac Classic almost mute

  1. #1
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    Default Mac Classic almost mute

    Okay I've done some reading on this one.

    The last week I've been pulling out machines one by one and testing them to see that they're still alive. I remembered I had a Classic tucked away (actually I had two, but the second was broken and many years ago I accidentally broke the seal on the CRT, so that went garbage).

    The Classic still boots like a champ, but the sound is almost completely gone. I can just barely hear it with the volume cranked on headphones. Everywhere I've read it says 'bad caps'. Is that spot on or can it be other things?
    Are there particular caps to target? Or do I need to replace the whole shebang like most of these folks seem to?

  2. #2
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    Replace them all.
    = Excellent space heater

  3. #3
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    Leaking SMD electrolytic caps tends to be a scourge on late '80s/early '90s Macs. They will all have to be replaced, as detailed here. In any case, it's a good idea to open the unit up and remove the PRAM battery, if it hasn't already been pulled. I had a Maxell 1/2-AA leak inside my Mac Classic, and the results weren't pretty. Fortunately, I had a spare logic board lying around, so I was able to bring it back to life.
    -Adam

  4. Default

    Quote Originally Posted by falter View Post
    The Classic still boots like a champ, but the sound is almost completely gone. I can just barely hear it with the volume cranked on headphones. Everywhere I've read it says 'bad caps'. Is that spot on?
    Yep.

    __

  5. #5
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    Agree, caps are likely the cause, also agree to replace all of the surface mount electrolytics. Many machines will continue to mostly function while the capacitor electrolyte is doing permanent damage to the logic board. I've got a few Mac logic boards in the scrap bin due to, "oh, but it still boots most of the time" mentality when it comes to capacitors. As mentioned, replace the 1/2AA PRAM battery too, and while you're in there, replace the nonpolar/bipolar electrolytic on the analog board with a film capacitor.

  6. Default

    Quote Originally Posted by glitch View Post
    Many machines will continue to mostly function while the capacitor electrolyte is doing permanent damage to the logic board. I've got a few Mac logic boards in the scrap bin due to, "oh, but it still boots most of the time" mentality when it comes to capacitors. As mentioned, replace the 1/2AA PRAM battery too, and while you're in there, replace the nonpolar/bipolar electrolytic on the analog board with a film capacitor.
    I watched my own Mac Classic degrade and deteriorate over an approximately 5-year period from leaking capacitors. I knew that was probably the problem, but it would still boot up and function, so I never did anything to it. Until it stopped working completely.

  7. #7
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    It wouldn't hurt to plug/unplug something into the external audio output a few times. And give a listen to that output with headphones or external speaker. The jack's switch can become oxidized or possibly the internal speaker has gone bad.

    My own experience with old electronics is that cap failures aren't as rampant for me, though they do certainly die at some point. I think low humidity helps and we're generally cooler here in summer. An iMac G5 was one notable exception - the multilayer board board with its "lead-free" solder was murder to replace the through-hole caps. I eventually trashed it.

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