Troubleshooting computers

Mostly it is done by board/module swapping.

Steps that can be used (but not often used as a scope is often required):

1/ Check all supply voltages 2/ Verify the clock signal 3/ Verify all inputs 4/ Verify activity on the busses

You pretty much can't. Most computer shops don't even own a DMM.

I have a related question: how would you troubleshoot a motherboard which resets CMOS to default every time a/c power is shut off, even with a fresh battery?

I have another identical board (ECS N2U400-A ver1.0) which functions just fine, and thought about doing an A-B type comparison with a meter, but I'm not sure what to look for.

Bad CMOS ram or bad battery connection. How much current does it draw from the battery while off?

I haven't yet got to the point of measuring current drain, but the battery seems to be holding at 3v.

However when this problem first cropped up, the original battery was weak. So maybe there is a drain somewhere.

Voltage is only useful diagnostically on the CMOS chip. Current is a quick and dirty check.

Are

That was pretty much my line of thinking. Sometimes the "boss" doesn't understand that though. Thanks. Brian

Bad jumper plug for reset CMOS function?