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Macintosh Plus (originally 128K) International Analog board capacitors / components

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I have a 128K which was upgraded back in the day to a Plus. It has the 128K front and the Plus 1MB back case. Logic board and Analog board are Plus parts.


It powers on but has no video. I suspect some worn out components on the analog board.


Straight away upon inspection - the C1 capacitor is bulging badly at the top, and leaking at the bottom. So I've removed that, and now I'm finding it hard to find a replacement!


The capacitor says 35 V 3.9 uF (M) on it.


The analog board is part number 630-0108 - it's stamped with 'International'. (I'm in the UK...)


I checked this well-circulated list of components for the analog board, but it says C1 is 3.9µF 100V. However this list seems to be for U.S. analog boards only...




So does the International version of the board use a lower voltage capacitor, or are they interchangeable ?


I also removed the two RIFA film capacitors, as they looked ready to explode and are badly cracked. These are marked RIFA 4700pF PME 271 Y 250V~SH . What can these be replaced with?


Photos attached if it helps.


Thanks in advance.



Edited by joshc

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Woops, I might have answered my own question with the paper capacitors...I am fairly certain these are the correct replacements. Unless anyone knows of a more robust component to replace them with?



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Potential replacement for C1?




Seems like its OK to change to a higher voltage as I believe that's an upper limit? This is also 105 C vs the original 85 C rated one so should last a bit longer perhaps.


I'm still keen to hear from others here regarding what you've used for the C1 capacitor on your Plus analog board.


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I haven't actually done my Pluses yet, but I was planning to use a ~100V cap personally since that's what I have in my big drawer o' capacitors (I too am in the UK).  I don't think it matters unless the rated cap voltage is *stupidly far* above the voltage at point of use.


That said, I'm by no means an expert...

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