Mac Plus - Video only when analog board pushed

eric

Administrator
Staff member
Sep 2, 2021
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bluescsi.com
It's a very common problem with the 128/512/Plus models - cracked solder joints on the analog board. Take a look at the board with the paper off (careful dont touch anything if on main power, and even off as some early models don't have bleed resistors) - look at all the solder joints and see if you notice cracks. It's pretty easy to get a soldering iron and add new solder to all those connections and get video back. The cracks are usually on the flyback and/or the analog board connector to the logic board.

Hope that helps - enjoy your Plus - it was our first Mac and had the exact same problem.
 

S. Pupp

Tinkerer
Apr 2, 2023
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The Mac Plus I bought new in 1986 developed this as an intermittent problem at age 6. Eventually I replaced the solder at the flyback transformer's leads, as eric described, and that solved it. In my case, the connections looked OK, so I'd recommend replacing the solder at these connections (and the analog board connector) even if you don't see a problem.