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Mac II mobo: which one of the batts is necessary to start?
Posted by: Macbuk on 2008-06-11 13:30:09 Hi there... I bought a couple of extended II motherboard to test. I'd like to have some functioning spare parts to address bad eveniences. I deeply washed them and i'm ready to try. http://img65.imageshack.us/img65/540/mbii1om0.jpg http://img88.imageshack.us/img88/8169/mbii3pt4.jpg I would like to know which one of the two batteries is mandatory for Macintosh II and IIx to boot. I would try a rapid test. regards
Posted by: equill on 2008-06-23 11:23:14 Here's the story, and a link to a circuit schematic as well. Read, especially, Kallikak's posts. The batteries are in series. A tap at their junction looks after PRAM/clock. The sum of the battery voltages is used to kickstart the power supply. For startup, it becomes academic which of the batteries is failing if that sum does not exceed 5V, and if the lower battery fails faster, the clock also fails. de
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