PSU died, what should I look for?

[DerStrom8]

Good day everyone!

I have decided to purchase a new desktop computer from a friend of mine, who offered me a stupidly-good deal on it. It's a custom built PC with the following parts and specs:

Cooler Master Centurion 5 case with clear side panel
Gigabyte EX58-UD3R Motherboard
Intel i7 3.4ghz processor
Cooler Master V8 Cooling system
3GB OCZ 1600mhz RAM
2 ATI Hydravision 4650 Graphics cards
Cooler Master 650W power supply
Seagate Barracuda 500 GB 7200 RPM Hard Drive


I did some research and found that if he parted it out, he could get well over $1000 for it, but he was willing to sell it to me for only $400. After a couple of days of thinking, I decided to snatch it up. An offer like this only comes once or twice in a lifetime!

Anyway, I knew that the first thing/s I'd want to upgrade are the RAM (I'm buying 16 gigs from another friend for $50), and the hard drive. I realize some of the parts are somewhat old, but they seem like they'll still be fine for my purposes.

Anyway, now for my question:

He recently reconnected everything to test it out (before I bought it) and make sure everything still worked, but for some reason it wouldn't POST. Some of the lights came on, but the computer just wouldn't start. He narrowed it down to the power supply. He replaced it with a smaller unit he had (just to test it out) and it worked. Eventually he decided that he would be willing to sell it to me for $330, since the power supply (the Cooler Master GX) costs about $70, and he'd let me have the old PSU. I was thinking there was a chance I could repair it, in which case I could save $70. The problem is that I only started with computers about a year ago and am still learning the inner workings. I know that power supply failures are often caused by bad caps, but bad caps are often caused by other underlying problems. I know you guys are mostly computer technicians, so I thought you might be able to give me a hand here. What should I look for when attempting to repair a damaged PSU?

Thank you!
Regards,
Matt

[ratdude747]

Re: PSU died, what should I look for?

Assuming the PSU is a good brand of good build quality, the first thing to see what exactly isn't working.

If the system won't start, look here:

Question #1. Does the PSU start when told to power up. Shorting the green wire on pin 16 (14 if 20 pin) to ground should make the PSU start up.

If it doesn't start, Check the 5vsb voltage on pin 9 (purple). It's not a bad idea to cjeck this even if it does run, since certain 5vsb designs are prone to motherboard frying failure via overvoltage.

If it does start, check all the voltages. Don't forget the power-good line on pin 8 (gray); if there's no voltage there, then the motherboard will not POST.

If you have access to a scope (or analog multimeter), then you can also check for voltage fluctuations. The voltages should be pretty clean w/o much ripple.

---

If it is a different issue (say the fan won't spin up but all else comes on), then say so... there's a different routine for those failures.

[retiredcaps]

Re: PSU died, what should I look for?

What should I look for when attempting to repair a damaged PSU?

When I get a new ATX PSU, I always open it up first and inspect it for any obvious bad components.

Then I put the shield back on and measure voltages with a multimeter. Depending on what I get, I go from there.

[retiredcaps]

Re: PSU died, what should I look for?

Obviously, the moderator's response gets ahead of the regulars!

Ratdude747 has a more detailed response anyway.

[DerStrom8]

Re: PSU died, what should I look for?

Assuming the PSU is a good brand of good build quality, the first thing to see what exactly isn't working.

If the system won't start, look here:

Question #1. Does the PSU start when told to power up. Shorting the green wire on pin 16 (14 if 20 pin) to ground should make the PSU start up.

If it doesn't start, Check the 5vsb voltage on pin 9 (purple). It's not a bad idea to cjeck this even if it does run, since certain 5vsb designs are prone to motherboard frying failure via overvoltage.

If it does start, check all the voltages. Don't forget the power-good line on pin 8 (gray); if there's no voltage there, then the motherboard will not POST.

If you have access to a scope (or analog multimeter), then you can also check for voltage fluctuations. The voltages should be pretty clean w/o much ripple.

---

If it is a different issue (say the fan won't spin up but all else comes on), then say so... there's a different routine for those failures.

When I get a new ATX PSU, I always open it up first and inspect it for any obvious bad components.

Then I put the shield back on and measure voltages with a multimeter. Depending on what I get, I go from there.

That's great information guys, thanks!

I haven't officially bought it yet, so I don't have the PSU. I'll take a look at it as soon as I can and let you know what I find.

@Ratdude, excellent instructions there. Can't thank you enough

BTW, when I was a kid my sister had two rats--Jack and Houdini. Great little critters-make excellent pets!

Much obliged.

Matt

[DerStrom8]

Re: PSU died, what should I look for?

Obviously, the moderator's response gets ahead of the regulars!

Ratdude747 has a more detailed response anyway.

I thank you for your willingness to help though. It is very much appreciated. What you suggested is probably where I'll start, just in case something was connected wrong when he plugged it into the computer. If it turns out the outputs are bad, then I'll proceed to follow Ratdude's suggestions

Regards

[DerStrom8]

Re: PSU died, what should I look for?

UPDATE:

I just talked with the guy, and he's going to let me pick up the PSU tonight instead of waiting until I can buy the rest of the computer. I should be able to get back to you tomorrow.

[DerStrom8]

Re: PSU died, what should I look for?

Okay, I got the PSU last night, but when I went to test it I realized I didn't have the power cord. I'll be picking one up this weekend, but it'll be a little while. Might be Sunday or Monday before I can even begin to test it.

Thanks for your patience guys.

Matt

[larrymoencurly]

Re: PSU died, what should I look for?

When I get a new ATX PSU, I always open it up first and inspect it for any obvious bad components.

By doing that I've found, in various PSUs:

1. nut rattling around (unknown purpose)

2. nut rattling around (held diode to heatsink)

3. Cracked solder on transformer wires.

4. Solder didn't stick to ground wires, wires pulled out easily.

5. AC ground wire lug really loose.

6. Small upright capacitor on the low voltage side touched lug on AC receptacle; newer version of the same PSU had that capacitor lay flat against the circuit board.

7. Pea-size blob of solder slightly embedded in high voltage wire insulation.

8. Soldered component lead bent over and touching copper trace next to it. PSU worked again after the lead was cut back.

[retiredcaps]

Re: PSU died, what should I look for?

Even after I do an pre-inspection, stuff like the following still happens

https://www.badcaps.net/forum/showthread.php?p=188155

[DerStrom8]

Re: PSU died, what should I look for?

So I finally got the chance to plug in the supply and test the outputs of the ATX plug. Everything was as it should be. I'll be doing a few more tests once I can get everything connected, and I'll post back here with what I find.

Regards

[DerStrom8]

Re: PSU died, what should I look for?

@ratdude747

I was told that you should be able to plug your PSU into an outlet and turn it on before connecting any of the outputs to the computer. If the fan came on, it was good, if it didn't, there was something wrong. The fan will not turn on when the unit is simply plugged into an outlet and not into the computer, but it will start up when I short the power on wire (green) to ground. Does this mean there is, in fact, a problem with the supply? And if so, we can narrow it down to something that would cause the unit to not power on when simply plugged in and switched on (switch in the back), but would start up when the pwr_on connection is shorted to ground.

Any thoughts? Your help is appreciated

Best wishes,
Matt

EDIT: I feel like a moron now. I should have done a little more research and testing on my own before posting here. I never connected the power switch connector to the motherboard! Now when it's turned on the PSU turns on, the lights all turn on, etc. The only problem now is that it just won't POST. It doesn't seem to be a problem with the PSU--every output is the correct voltage. Any other reasons why a computer won't boot?

[LDSisHere]

Re: PSU died, what should I look for?

You should try a different power supply if you have one available. The one you have may work fine unloaded but have problems when it has a real load placed on it.

If you do not have another supply to use you will want to reduce the load on the one you have as much as possible. If the board has integrated video use that and remove every thing but one stick of ram and processor, reset the CMOS and then see if it will post. If it will not post at this point you should check the power supply voltages while it is connected and attempting to post.

[DerStrom8]

Re: PSU died, what should I look for?

You should try a different power supply if you have one available. The one you have may work fine unloaded but have problems when it has a real load placed on it.

If you do not have another supply to use you will want to reduce the load on the one you have as much as possible. If the board has integrated video use that and remove every thing but one stick of ram and processor, reset the CMOS and then see if it will post. If it will not post at this point you should check the power supply voltages while it is connected and attempting to post.

Thanks LDSisHere. I don't currently have another PSU available. I will in a day or two, but for the time being it's just blind testing.

My computer has two removable video cards. I've removed one, and removed all but one of the 1GB RAM cards. I couldn't find the CMOS reset button or connector/jumper, so I removed the battery for a couple of seconds and replaced it. I need to hook it up to the monitor again, and I'll let you know what happens.

Thanks for the help

Matt

[RJARRRPCGP]

Re: PSU died, what should I look for?

Thanks LDSisHere. I don't currently have another PSU available. I will in a day or two, but for the time being it's just blind testing.

My computer has two removable video cards. I've removed one, and removed all but one of the 1GB RAM cards. I couldn't find the CMOS reset button or connector/jumper, so I removed the battery for a couple of seconds and replaced it. I need to hook it up to the monitor again, and I'll let you know what happens.

Thanks for the help

Matt

If you know how to use the clear-CMOS jumper correctly, you don't need the battery out for more than a few seconds.

But, you must set the jumper pins to the other position for a few seconds then put the jumper back to the original position before popping the CR2032 battery back in.

[DerStrom8]

Re: PSU died, what should I look for?

If you know how to use the clear-CMOS jumper correctly, you don't need the battery out for more than a few seconds.

But, you must set the jumper pins to the other position for a few seconds then put the jumper back to the original position before popping the CR2032 battery back in.

If you re-read my post, you'll see that I said,

I couldn't find the CMOS reset button or connector/jumper

I would not have removed the battery if I had found the connector/jumper. The battery was my last choice. I removed it for a few seconds, then put it back in.

I had looked up how to reset the CMOS, but couldn't find the reset jumper. If I had found that, I don't think I would have needed to remove the battery at all.

That's what I found in my research, anyway.

Thanks for the responses.

Regards,
Matt

[RJARRRPCGP]

Re: PSU died, what should I look for?

If you re-read my post, you'll see that I said,



I would not have removed the battery if I had found the connector/jumper. The battery was my last choice. I removed it for a few seconds, then put it back in.

I had looked up how to reset the CMOS, but couldn't find the reset jumper. If I had found that, I don't think I would have needed to remove the battery at all.

That's what I found in my research, anyway.

Thanks for the responses.

Regards,
Matt

I was just pointing that out, because there's a myth circulating around the internet, telling people to leave the battery out overnight!

And it appears that you must also remove the battery on later boards. The old school Soyo didn't require that..

But, definitely don't need to for more than 1 minute!

[DerStrom8]

Re: PSU died, what should I look for?

I was just pointing that out, because there's a myth circulating around the internet, telling people to leave the battery out overnight!

And it appears that you must also remove the battery on later boards. The old school Soyo didn't require that..

But, definitely don't need to for more than 1 minute!

Thanks. Yup, I got my hands on a manual and it says to leave it out for exactly a minute, and put it back in.

Anyway, things have gotten very interesting here. I put in a different PSU that a friend lent me (one that definitely works) and it did the same thing--lights and fans turned on, HDD started spinning, beeped once at startup (looked it up--means everything's OK), but still no output to the monitor. I assume that would mean it's a problem with the graphics cards. Neither work though, and i'm hoping it's not an issue with the mobo connections themselves. If that's the problem, i'm looking at another couple hundred to replace the mobo. I just don't know why both cards would suddenly stop working?

I contacted the guy I got it from, and I'm thinking worst case scenario I'll get my money back. Or I might part it out and buy a completely different one with the proceeds I would like to get this rig up and running though. I've never seen anything quite like this. Hoping you guys might have some insight. Could it be a problem with the graphics cards? Is there a common failing point? I'll see about getting the specs of each one, since I probably haven't given you enough info yet.

Hope you all are well.
Regards,
Matt

[LDSisHere]

Re: PSU died, what should I look for?

If it was me, I would find a known working card to try in that board or I would try one or both of those cards in a known working computer. That may be easier said than done for you but it would answer a lot of your questions. I would venture to guess that the video cards have gone bad, I have had some do the same just sitting in a box.

[DerStrom8]

Re: PSU died, what should I look for?

If it was me, I would find a known working card to try in that board or I would try one or both of those cards in a known working computer. That may be easier said than done for you but it would answer a lot of your questions. I would venture to guess that the video cards have gone bad, I have had some do the same just sitting in a box.

You're absolutely right. I contacted the guy who sold me the computer, and he agreed to test the graphics cards in his machine. They worked fine. I am totally stumped, as are all the computer nuts who I've let take a look at my computer (I work at a technical university, remember? ).

I checked the CMOS battery and everything, voltage is fine. Tried resetting it, still no luck. Checked that the video card slots were clean (the best I could) and still nothing. I don't even know what to try next....