This article is from the Apple II Csa2 FAQ, by Jeff Hurlburt with numerous contributions by others.
Disconnect the monitor, remove the AC power cord, and open up the case. Warning: High voltages are present! For case opening directions, safety tips, and tool info, see Q&A 003-006 above. The power supply has about five components one of which is a big white ceramic resistor (3.3 ohms in the 110V colour monitor). You will probably find that the solder connecting this resistor has crystallized. Unsolder the resistor, scrape the leads with a Stanley knife (gently!). Clean the solder pads with some 200 grit wet and dry sandpaper. Resolder the resistor and voila! If the resistor is OK. Then check the "kickstart" cap in the power supply (by swapping in a substitute). You can also check the STKxxxx power supply chip for bad solder joints. Good luck! By: Stephen Shaw