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Troubleshoot three common PC problems with a multimeter

To quickly test a power supply I have in my tool kit an ATX power supply tester. You plug this tester into the motherboard power connector of your power supply, turn on the power, and this tester will indicate if your power supply is good or bad. It sells for $12.75 and can be found at http://www.cyberguys.com/

The ATX supply tester from Cyber Guys performs only a very cursory test.

It will tell wheter or not the power supply is dead. But offers no guarantee that the supply can actually power a motherboard.

It loads the +5 so that the power supply will run, and the LED shows that some voltage is present.

Luckily, the way an ATX switching power supply is designed, this is enough 90% of the time.

The only way to "test" a power supply is to properly load each output, and verify that the output voltage is within specified limits with low AC noise and ripple.

It is very possible for 1 supply to be dead at the ATX conector, but the rest of the supply will still run.

Chas

Is that how the motherboard turns the P/S on? by putting a load across the +5 volts?

>It loads the +5 so that the power supply will >run, and the LED shows that some voltage is >present.

I have been wondering about the feasability of using 2 ATX power supplies on one PC - but wasn't sure how the motherboard switched on the power supply. If I tap into the +5 v on the existing P/S and connect it to the same wires on the 2nd P/S, would this activate the 2nd P/S?

Stuart

The same tester can be purchased at the following url for a lowerprice. The url

The same tester can be purchased at the following url for a lowerprice. The url is http://www. pcpowerandcooling.com

Most often, the problem can be solved by simplifying the problem. Modern computers with soft power switches, higher speeds, and loads of accessories are often running near the limits of the power supply.

A high-drain USB device, a dislodged IDE cable, a power cable that's not perfectly seated, or memory that has worked itself loose can often cause what appear to be power problems.

I usually start removing items to eliminate external causes:
1) Remove all external devices except the monitor, keyboard, and mouse.
2) Open the case and make sure everything's seated.
3) Remove extra cards (LAN, sound, etc.) to leave only the minimum needed to boot.
4) Swap the video card if possible.
5) Remove all drive cables.
6) Remove all internal power cables except for the motherboard & fans.

If I get to this level and it's still dead, then it's time to grab the meter.

In a recent incident, a user had a computer that would boot as far as the "checking nvram" message and thenwould die. After an extended troubleshooting session, it turned out that an external USB hub had a loose power cord and had drained the board voltage to prevent booting.

Loose IDE and drive power cables, motherboard power, and loose boards canall interrupt the boot sequence and are worth verifying.