Tracing it down, its circuit is a very straight forward half bridge rectifier:ġ2v pin on Flyback transformer (measured 24v AC) -> Resistor R514 -> Diode D506 -> Test point It, too, was bad, showing 1.2v instead of the expected 12v. This eventually let me to the 24v rail, which I had missed earlier. I spent a good while trying to figure out how the 80v is generated and ended up drawing out the circuit diagram on a picture of the board: When in doubt, check (all) voltages! When I was still running into issues after replacing the capacitors I went ahead and checked the voltage test points:
I turned the screen back on again with a Mac connected, and it's definitely improved, but still no joy: Do vínku dostal velikost 14 palc, rozliení 640 x 480 px, 32 000 barev a video konektor DA-15. Here is the neck board, which showed no signs of bad capacitors:Īnd the frame of the monitor with the tube:īased on the mess around the board I decided to go ahead and replace all the caps in that area, which is mainly responsible for the high voltage side: Apple Basic Color Monitor byl uveden na scénu zaátkem roku 1993. One could argue it's a pretty bad design choice, but considering how many years it worked before finally breaking down, I suppose it's not that bad. Slowly cooking the capacitors behind them over the years.
#Macintosh 12 rgb display full#
The resistors in the front carry the full B+ voltage which means they run pretty hot. Once I opened it up it was clear that the capacitors near the back of the board were in very poor condition and had leaked badly, which is likely the cause of this issue. It was introduced with the Mac LC in October 1999 and uses a 13 Sony. When I first powered up the monitor it immediately showed this screen: The Macintosh 12 RGB Display was Apples first color display for the Macintosh.
Bought as faulty, it appears to suffer from a complete loss of sync, even without a Mac connected.
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