Computer just died, need sanity check...

NNakhleh

Junior Member
Jul 5, 2001
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Blech.

My main gaming rig developed a faulty CD burner (Plextor 16/10/40 IDE, started getting 4 flashing green lights reading even known-good pressed CDs), so I shut it down (it normally runs 24/7) to swap in a new Plextor 48/24/48. All I did was open her up (armed with anti-static wrist strap, of course), pop off the power and IDE cables, swap drives, confirm same jumper settings, and replace the two cables.

I fire up the power, and......no joy. No spin up, no beeps/POST LEDs, nothing. So I remove the power to the new drive, just in case it's faulty, but nothing changes. I verify that the system is getting power, no cords unplugged or breakers popped, and try rebooting a few more times. No dice. I've got an MSI 6341 v1.1 mobo, which has the handy little power-to-the-board led, and sure enough, it's on. I yank the plug, and a couple seconds later it goes out. Replug...still out. Push power, the little light comes on, but otherwise no joy. Push and hold the power button 5 seconds, and it goes out. Looks like the mobo is aware of what's going on, I think. I triple-checked all relevant connections (P/S to mobo, switch to mobo, PS to drives) to verify they're seated properly. No difference.

With my trusty DMM, I check an open 4-prong power connector. Red-Black, which should be +5V, reads .42 V when "on", and about .06 V when "off" (I checked another machine to make sure that its P/S also reads about .06 V even when off....must be some standard "feature" in the P/S or something). The Yellow-Black voltage, which should be +12V, was only about 0.01V when "on", 0 when "off".

From these things, my initial guess is that my < 2 year old Antec 400W P/S just gave up the ghost. However, I'm not an expert in how the mobo and P/S interact in the ATX standard to decide that power should be turned on to the system, and I know there is some relationship, as you (or I, rather) can't get an ATX P/S to turn on without it being hooked up to a mobo.

So, I'm soliciting opinions, corrections to my beliefs, or other simple tests to try to ensure that when I go to Fry's, grab the part, and proceed to gut/repair my system, I'm not wasting my time and money...

Any input would be appreciated, thanks in advance!

-Nadim
 

LiLithTecH

Diamond Member
Jul 28, 2002
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How are you reading the voltages?
Are you reading them connected to the Motherboard or disconnected?

If you read them directly from the wiring harness disconnected from
the motherboard (no load) , the PSU latches to a shutdown state which would
explain the output voltage reading you recieved.

An easy way to check to see what the PSU is in is to read the Gray (pin #8 PWR_OK) wire.
Read the voltage from the Molex connector connected to the motherboard, using the PSU as the ground.
It should read 2.4v - 5v under minimum load. No Load would be 0.4v (logic level low).

You may want to check the fuse. Some slow blow fuses blow, but still complete the circuit.

 

NNakhleh

Junior Member
Jul 5, 2001
14
0
0
Originally posted by: LiLithTecH
How are you reading the voltages?
Are you reading them connected to the Motherboard or disconnected?

If you read them directly from the wiring harness disconnected from
the motherboard (no load) , the PSU latches to a shutdown state which would
explain the output voltage reading you recieved.

I was reading the voltages from an open 4-pin power connector, while the P/S was connected to the motherboard. I've encountered the situation you describe before, when I was building a system and testing things out before connection the P/S to the mobo, which is why I did the tests while it was connected.

An easy way to check to see what the PSU is in is to read the Gray (pin #8 PWR_OK) wire.
Read the voltage from the Molex connector connected to the motherboard, using the PSU as the ground.
It should read 2.4v - 5v under minimum load. No Load would be 0.4v (logic level low).

I thought about checking some of those pins, and looking up the ATX spec, but I didn't see a good way to check the molex connector's outputs while it was connected. Do you need a special break-out hookup, or can you do it with the stock connector?

You may want to check the fuse. Some slow blow fuses blow, but still complete the circuit.
[/quote]

I assume the P/S fuse is inside the "no user-servicable parts" P/S box? Not that that's a problem. (Remember, self....one arm behind your back at all times....) ;)

-Nadim
 

RemyCanad

Golden Member
Sep 28, 2001
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Haved you pulled everything out yet? Just leave the motherboard and powersupply. Start it up and see what happens. Then put the CPU in start it up see if you get a beep. Put the memory in, see if it beeps. Put the graphics card it, see if it beeps. So on and so forth.
 

NNakhleh

Junior Member
Jul 5, 2001
14
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Originally posted by: RemyCanad
Haved you pulled everything out yet? Just leave the motherboard and powersupply. Start it up and see what happens. Then put the CPU in start it up see if you get a beep. Put the memory in, see if it beeps. Put the graphics card it, see if it beeps. So on and so forth.

Gack! I certainly try to avoid ripping out CPUs (especially no-overheat-shutdown-protection Athlons) any more than necessary. Given that I had a completely working computer to start, and did just one little thing (swapped a drive in its bay), I would think that rebuilding the machine is sort of a brute-force approach to divining the problem, and in fact could make things worse, because instead of changing only one variable (the drive), now I've changed all of them...

Granted, if swapping out the PSU doesn't fix this problem, I'm probably looking at the mobo next, in which case it's no extra work to try this approach, but if I have to do all that I might as well upgrade the mobo anyway, so I can get my serial ports back (my current mobo got its ports fried by my stupid Palm Vx...thanks Palm!).

-Nadim
 

SemperFi

Platinum Member
Apr 5, 2000
2,002
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I think you are right on about the power supply. Do you have access to one to try before you buy?

I have solved some power supply problems by taking the cover off and taking canned air and blowing the dust out. As long as you don't start touching the componets inside you will be fine. From my experience this only helps with systems that are flaky and like to shut down randomly. You can look for a fuse while you have it open. I have not ever seen a ps with a fuse in it. But I have not ever had to take apart a good ps. ;)
 

NNakhleh

Junior Member
Jul 5, 2001
14
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Originally posted by: SemperFi
I think you are right on about the power supply. Do you have access to one to try before you buy?
Not one that isn't being used. I ain't touching my 24/7 server, and I don't think I have any others powerful enough. Although I typically by my components on-line, this is clearly a case for Fry's generous return policy...

I have solved some power supply problems by taking the cover off and taking canned air and blowing the dust out. As long as you don't start touching the componets inside you will be fine. From my experience this only helps with systems that are flaky and like to shut down randomly. You can look for a fuse while you have it open. I have not ever seen a ps with a fuse in it. But I have not ever had to take apart a good ps. ;)

This 'puter isn't flaky, it runs day in and day out, rock-solid. I haven't opened a P/S before either, but there's a first time for everything. However, it couldn't hurt to blow some compressed air around just in case... And if the P/S turns out to be faulty and unfixable (hopefully a new P/S will demonstrate this to be true), I'm gonna hook up the caps, one by one, to a car battery, backwards, as a warning to other components that think it would be a good idea to go bad before their time... :|

-Nadim
 

SemperFi

Platinum Member
Apr 5, 2000
2,002
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You don't really need to have a powerful supply. You can leave drives unpluged. You just neet to see it fire up since you can't get that far with the current one.

Semper Fi
 

NNakhleh

Junior Member
Jul 5, 2001
14
0
0
Originally posted by: SemperFi
You don't really need to have a powerful supply. You can leave drives unpluged. You just neet to see it fire up since you can't get that far with the current one.

Semper Fi

True, true. If it was right after Christmas, or after closing time, I'd probably just do that. But, in the current circumstances, I figure a second trip to Fry's would be less hassle than gutting my g/f's computer to get at another P/S. I don't think I have any other known-good ATX ones lying around outside of a machine right now. Besides, I still need to pick up UT2003 anyway. ;)

-Nadim

I just hope the new P/S does it...
 

alm4rr

Diamond Member
Dec 21, 2000
4,390
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check the capacitors on the board - see if any are slightly bulging at the top or have orange crusty stuff on them. If so, ur mobo is fried.
 

NNakhleh

Junior Member
Jul 5, 2001
14
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Thanks for all the advice, guys. I stopped by Fry's on the way home, and the "open case surgery" is complete. Prognosis, the patient lives! As it turns out, the P/S had in fact gone bad. I did the preliminary check recommended by Lilithtech, and sure enough, the PWR_OK pin was reading a palty .4V, so the P/S knew it couldn't "get it up", I guess.

Anyway, I swapped in a newer Antec TruePower 380W P/S, which looked a little better designed, even though it's rated at 20W less, and it's running like a champ. :D

As for the old one....hmmm....a little post-mortem is in order. For a P/S rated at 50,000 MTBF, dying so soon (I bought it 6/20/01, so given 24/7 runtime, which it does, pretty much, we're talking about 10,800 hours), that's pretty poor. I popped it open, didn't see and failed caps, any scorch marks on the board, anything else noteworthy. In answer to those of you talking about a fuse, I found something pretty funny. There's something that looked like either a power resistor with no marking lines or a fuse tube that was opaque white, not transparent. Next to it is silkscreened: "WARNING: For continued protection against risk of fire, replace only with same type and rating of fuse." So, a fuse it must be. Except, as I pointed out, it's not clear, so you can't tell if it's blown. And, by the way, it's soldered in. Oh, and then glued down, just in case someone wanted to unsolder it. Talk about not being user-friendly... I thought it was a bit funny to put the warning there if you're going to go to such great lengths to make sure nobody (but a trained tech) tries to replace it. :confused:

Just for kicks, I check it (in place) for continuity, and the meter beeped happily away. Oh well, who cares, the computer works... :)

-Nadim
 

Buz2b

Diamond Member
Jun 2, 2001
4,619
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Just an afterthought here. Antec makes an ATX PS testor (they have them at Fry's and CompUSA) and for only about $12, you could save yourself a lot of time and effort in the future. Not a fancy piece of hardware or anything like that. Just connect it to the ATX MB cable fromt the PS and turn on the PS. If it lights up, it's good. IF not, it's bad. You can also check voltages while it is connected to verify things.
 

NNakhleh

Junior Member
Jul 5, 2001
14
0
0
Originally posted by: Buz2b
Just an afterthought here. Antec makes an ATX PS testor (they have them at Fry's and CompUSA) and for only about $12, you could save yourself a lot of time and effort in the future. Not a fancy piece of hardware or anything like that. Just connect it to the ATX MB cable fromt the PS and turn on the PS. If it lights up, it's good. IF not, it's bad. You can also check voltages while it is connected to verify things.

Interesting. I didn't see it at Fry's, but then again I wasn't looking. Sounds like a nice piece of gear for someone who builds/repairs boxes on a larger scale than me.....but personally, I have a feeling that if another one of their power supplies goes, I'll have a strong desire to start purchasing less Antec gear, not more...;)

-Nadim
 

Buz2b

Diamond Member
Jun 2, 2001
4,619
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NNakhleh,
While I wouldn't blame you for that, usually Antec is better than what you may have been experiencing. :) As to the necessity of the testor, yes it comes in handy when you build a lot of boxes, as I do, but I got this little "gem" long before I started doing so. It so happens that I experienced the same thing (almost) as you and lost a PS. Only I didn't have much knowledge then, nor the insight to this place. Instead I paid~$45 for someone to "diagnose" this trouble for me and then another $50 for the PS. I swore that I would never let that happen again; hence the testor. Since that period long ago and after building between 60-80 boxes, this testor has come in handy more than just a couple of times and has paid for iteself many, many times over. Before I even got more involved in building units, it also "saved" a couple of friends a few bucks. I guess what I am saying that it might be the best $12 you could spend; if not for the money, since you can get hlep here, then for the time it could save you.
Good luck and sorry about your troubles also.