Hello, my Macintosh Classic II after several month good work dont start up I power on, it makes noise but no start up sound, and monitor is black. What did can broken ?
Depending on the kind of sound it's making, like electrical buzzing or zapping, the powerboard could have blown out. I would recommend not turning it back on until you get a new powerboard. If that is the case.
Some people have had success of reviving motherboards by running them through the dishwasher or cleaning the "capacitor corrosion" by hand with soapy water/rubbing alcohol. If you try this make sure you have rinsed it and let it dry completely before powering it. (Let it sit out in room temperature overnight.)
Great thanks ! I wash motherboard with soap, after in alcohol and all perfectly works, I plane to change capacitors and again wash motherboard in ultrasonic bath.
I have had good success in reviving a Classic II, and a number of other machines, just by washing the logic boards, but I leave the boards to dry for longer than overnight. I tend to give them a few days at least.