Please Provide Precautionary Advice...

[micjmac]

I was considering picking up a DMM locally to test my PSU. I read the stickies, but considering I am dealing with a large investment (my PC) and something very dangerous (electricity), I feel that my OCD here is warranted.

Basically, I am just looking for anything that might seem obvious (even if it is common sense) that I should avoid doing when measuring the voltages.

Here is what I know:

1. Don't set the DMM to measure amperage (I don't know why, but I have read it in at least 2 different locations)

2. Work on a table (not sure if this really matters...can I work on the floor or is that going to cause problems?)

3. Put the ground (black) probe into a ground pin on the Molex and the red probe into whichever voltage pin that I want to measure on the Molex

What I don't know:

Basically, I need to know which objects absolutely shouldn't touch whichever other objects without causing problems (for example: can the red wire and black wire of the DMM touch each other...can they touch the case....can I touch the DMM while I'm measuring...etc.)

Also, check my sig for the PSU. Apparently this thing has multiple rails, so I am not sure how this is going to affect the accuracy of my measurements.


Sorry for being clueless. I don't really feel like getting elecrocuted...

[johan851]

1. Don't set the DMM to measure amperage (I don't know why, but I have read it in at least 2 different locations)
In amperage mode, the connection between the two multimeter leads is a short. If you set it to amps and measure between ground and, say, the 5V rail, you'll short the rail to ground. That would probably damage the PSU and probably blow a fuse in your DMM. The proper way to measure amperage is to cut the connection and reconnect it through the leads, but there's not a lot of reasons why you would need to do that.

Basically, I need to know which objects absolutely shouldn't touch whichever other objects without causing problems (for example: can the red wire and black wire of the DMM touch each other...can they touch the case....can I touch the DMM while I'm measuring...etc.)
It's never a problem to touch the leads of the DMM together. In voltage mode, the connection between the two leads is an open circuit, so you shouldn't be able to hurt anything you're measuring. You DO need to be careful that you don't touch two things with one probe, because that would cause a short. You can certainly touch the DMM while measuring things.

There's very little danger of you being electrocuted (the voltages in a computer are all 12V DC or less, which is harmless) but more danger of you shorting something out and damaging your gear.

Why do you want to test your PSU? If that's the only reason you're getting a DMM, it's not worth the trouble in my opinion.

[Bobnova]

johan covered it nicely, as long as you only touch one (1) thing at a time with the red lead, and the black lead is only touching one (1) thing (stuffed into a connection with a black wire in a molex or somesuch), you can't kill anything.

[micjmac]

Why do you want to test your PSU? If that's the only reason you're getting a DMM, it's not worth the trouble in my opinion.

After about 4 months of use, my system is experiencing random shutdowns while attempting to boot. This is the exact kind of scenario that I read in the product's reviews on newegg. After the random shutdowns, the PSU ultimately fails in the near future. Although this may be totally unrelated to the PSU, I am also experiencing crashes while watching replays on Starcraft 2.

Honestly, I'm at the point where I might as well just take the money for a DMM and just invest it in a new PSU.

Can you guys check my sig and take into consideration that I will probably upgrade the video card and overclock the i5 at some point. Would the Corsair 650TX be enough for this application?

[johan851]

The 650TX should be enough as long as you don't go for an SLI setup or an extremely power hungry graphics card. The Earthwatts EA650 is supposed to be a great PSU, though, so I'm surprised you're having trouble. It should have a 3-year warranty - maybe you could just RMA it?

[micjmac]

In amperage mode, the connection between the two multimeter leads is a short. If you set it to amps and measure between ground and, say, the 5V rail, you'll short the rail to ground. That would probably damage the PSU and probably blow a fuse in your DMM. The proper way to measure amperage is to cut the connection and reconnect it through the leads, but there's not a lot of reasons why you would need to do that.


It's never a problem to touch the leads of the DMM together. In voltage mode, the connection between the two leads is an open circuit, so you shouldn't be able to hurt anything you're measuring. You DO need to be careful that you don't touch two things with one probe, because that would cause a short. You can certainly touch the DMM while measuring things.

There's very little danger of you being electrocuted (the voltages in a computer are all 12V DC or less, which is harmless) but more danger of you shorting something out and damaging your gear.

Why do you want to test your PSU? If that's the only reason you're getting a DMM, it's not worth the trouble in my opinion.

The 650TX should be enough as long as you don't go for an SLI setup or an extremely power hungry graphics card. The Earthwatts EA650 is supposed to be a great PSU, though, so I'm surprised you're having trouble. It should have a 3-year warranty - maybe you could just RMA it?

Please define power hungry card. Also, please keep in mind that when I ultimately upgrade the graphics there will probably be more impressive and hence more power hungry cards out in the future. I will admit, though, that I would probably aim for one of the elite cards that are out right now after their prices drop significantly in a couple of years.

As far as RMA, I plan to get the replacement that I should be entitled to under warranty, but honestly, based on the reviews and my own experience with this Antec PSU, it is a crapshoot (so I'll probably just sell the RMA). The majority of the negative reviews are DOAs. Then there are also a small percentage of random PSU failures (which is to be expected). What disturbed me the most about this PSU are the small number of reviews that demonstrated identical situations to the one that I am experiencing (random shutdowns during boot-up after several months of use).

[johan851]

Please define power hungry card. Also, please keep in mind that when I ultimately upgrade the graphics there will probably be more impressive and hence more power hungry cards out in the future. I will admit, though, that I would probably aim for one of the elite cards that are out right now after their prices drop significantly in a couple of years.
Fortunately, efficiency is going up as cards continue to get faster, so the growth in power isn't too ridiculous. An extremely power hungry card, in my mind, is some kind of ridiculous dual-GPU solution like the HD4870 X2.

[theflyingrat]

The 650TX should be enough as long as you don't go for an SLI setup or an extremely power hungry graphics card. The Earthwatts EA650 is supposed to be a great PSU, though, so I'm surprised you're having trouble. It should have a 3-year warranty - maybe you could just RMA it?

The 650TX is plenty for nearly any (excluding GTX 480 SLI, tri-sli, etc.) SLI or CrossfireX setup... as should an EA650.

[larrymoencurly]

You can't get electrocuted unless you hook up the meter to high voltage, such as by sticking a probe into an AC outlet or PSU. BTW, before you try a cheapo multimeter with high voltage, tug on their ends and wires and wiggle the tips to verify that they won't fall apart. Because when I tried measuring a 120VAC outlet with a Harbor Freight multimeter, one of the metal tips pulled out of a probe. This happened with only 1 of 6 probes (3 meters -- coupon abuse).