[henrytaylor]

I have a G3 700 w/Applecare. Recently the LCD screen developed the problem of dimming while in operation. Just for a moment it dims, then back to normal. I'll call Applecare about this.
My question is, has anyone else had this problem? What can I expect from Apple, and what tales can you tell, even the horror ones.

Thanks,
Henry

[ghporter]

I haven't had this happen to me, but I can tell you what's happening to you. The screen is lit by a device that uses alternating current (AC) at either a high frequency, a high voltage, or both. Since the laptop runs on direct current (DC), it uses a device called an inverter to produce the needed AC. Inverters typically use a set of fairly beefy switching transistors to create the AC. The inverter usually powers a pair of cold cathode tubes, which produce a very white, fairly cold light.

There are two basic situations that can cause your type of problem. Sometimes the transistors start to wear out, or they develop problems with heat, which can cause their output to drop. Note how often and how long each episode of dimming occurs and keep your eyes on whether the come more frequently and/or last longer; this is a sign that the inverter is getting worse.

The other possibility is that the cold cathode tubes are starting to fail. Since they work at high voltages and frequencies, they can be prone to problems with heat or vibration.

Neither of these problems is at the user-maintenance level, so AppleCare is really your only route here.