Hi, I have been troubleshooting lots of Macs lately at my job (mostly iMacs) and want to make it easier on me in future visits.

The most common problem I've seen lately is a folder with a question mark in it blinking. Great...it's a corrupted OS right? I tried reinstalling by booting off the Mac CD. It won't boot from it. I tried swapping out the CD drive...then also the hard drive when CD still won't boot from it. Still nothing. I brought it for in-house repair and they guys over there said they repaired a "bad contact". Is it safe for me to assume that this bad contact could mean anything inside that's out of place? Or is this "bad contact" an actual component in the Mac?

The other problem I encountered last week was a flickering screen. It would flicker from time to time and in about 5 - 10 minutes into the bootup, it will either flicker a few more times and freeze on you...or just shutdown for no reason. Bad analog board?

Seems like a lot of these problems with Macs is the analog board. This board provides the video and also power to the Mac right? Is there anything else its responsible for?

This will really help me out a lot. If you guys know of any other common Mac problems (be it iMac, eMac or the old PowerMac G3's), please list them here. I hate taking these things in-house when I can't repair them on the site.

Thanks.

The flickering sounds like a bad logic board. That is exactly what my old iBook did each time before having its logic board replaced (3 times I might add)

A bad contact would be something on the motherboard or logic board was loose. I've seen this with many types of computers and electronis were things get loose and they won't work. Someone with a solder gun that knows what they are doing can be a big help.

Fortunately I live around a retired electrical engineer, so I buy him lunch every once in a while for helping with electronic repairs and with my pet projects. I think he just gets a kick out it just to give him something to do.

The guys in the office finally replaced the analog board which was my first guess. The flickering stopped after that...

I usually open up the iMacs and check the insides. I didn't notice anything loose or misplaced in there though. The bad contact is on the logic board side right and not the monitor side? We don't touch the part where the monitor circuits are...so if it's there, I guess we can't fix those on site.