128k and 512k blown fuses

[danc]

Hi

I recently picked up a 128k and a 512k mac in untested condition - when i got them home i have found that the fuses on the power supply are blown. I suspect this is due to someone plugging them into the 240v mains power we have here in NZ when the computers require 120v. What damage is likely t have occurred minus the fuses? Nothing looks blown or burnt within the computers - they look very clean. Replace the fuse and we are away?

 

[Elfen]

Is there a burnt smell to the analog board? And does the Analog board have a 120/240 wire jumper on it or is it 120VAC only? Some analog boards have this, others don't. If it has it, check as to what position it is set on. It is usually a greenish-grey in color wire with a grey plastic connector that goes onto one of two large pins on the analog board.

You would have to go in with a multimeter and check the components on the board and make sure they are OK and not shorted out - WITHOUT TURNING ON THE MACHINE THAT IS!

Long ago when I was teaching analog board repairs in the 1990s, I ran up against an analog board that seemed OK but was dead. Then in teaching component level replacement, most of the parts were OK until I found a large diode on the board. It seemed OK by visual inspection but when I put the multimeter probe to it, it crumbled apart. It was replaced along with a few other parts and the analog board came back to life.

 

[danc]

Thanks for your reply. No burnt smell. Not sure on the 240/120 jumper - the label on the back of the computer says 120. I'll have to dig it out and have a closer look.

My experience with circuit boards is pretty limited past recapping... Any advice on where to start before I hit YouTube how to videos?