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Home Forums Macintosh plus anode cap => dead screen? — #23 Macintosh plus anode cap => dead screen? — #23
Post #23 by nvdeynde
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I've encountered an error in the mac repair document, in the text of the feedback control circuit they talk about the R56 potentiometer, but it should be the R59 pot, at least on my mac plus)
The repair document is probably right as it's made for USA versions of the Analog board working on 110 volts.

We in Europe have the International version at 240 volts that can work at 110 volts as well. That's why the numbers of the resistors and other components don't match on the schematics but also the values are different. So don't use the values try to repair your board.

In the American version it's indeed common for CR20 and CR21 fail, however I haven't seen one that goes bad on an International 240 volts board. So upgrading them to higher specs is also not needed in my opinion.

Go through the whole schematics of the board and test every component. In Larry Pina's book is a diagram with all the voltages you can check on over 10 spots. Have you done this test ?

Otherwise it's probably best to cut you losses and give up the board.

mp.ls