Computer PSU 5v drop

[lezsimply]

Good day, I have a Thermaltake 850 watts Toughpower power supply. I've tested it using a multimeter and I see 5v is dropping. It cannot boot my desktop pc anymore.

Other reading such 5v, 3.3v, 12v, -12v 5vSB are ok but the 5v shows only 3v. I just want to know what electronic component usually go out when 5v is dropping? I'm thinking about a DIY method on fixing this power supply. I think its not that complicated or is it? Thanks!

[ben7]

Re: Computer PSU 5v drop

Good day, I have a Thermaltake 850 watts Toughpower power supply. I've tested it using a multimeter and I see 5v is dropping. It cannot boot my desktop pc anymore.

Other reading such 5v, 3.3v, 12v, -12v 5vSB are ok but the 5v shows only 3v. I just want to know what electronic component usually go out when 5v is dropping? I'm thinking about a DIY method on fixing this power supply. I think its not that complicated or is it? Thanks!

Look inside, does it have any bulging capacitors?

Could you take some pictures also?

[lezsimply]

Re: Computer PSU 5v drop

I can't seem to find any bulging capacitors. I can take some pictures, I'll post it tomorrow. It'll be difficult to remove the power supply from the case because it has a separate board on top of it. I think I need to desolder it first to remove it.

[Th3_uN1Qu3]

Re: Computer PSU 5v drop

You may have a half-shorted 5v diode. I've seen that before. Take the PSU apart and post pics, and then i'll point at things you can check.

[lezsimply]

Re: Computer PSU 5v drop

Good day, this is the best image I can get, would this help? Its hard to see the whole components inside because its a little congested. Maybe I can remove those 2 huge heatsinks to make the view better. I also double checked if I missed some bloated capacitors but I see none. Thanks Again.

[pdavid]

Re: Computer PSU 5v drop

Interesting. I had the same problem with the same build (CWT PSH). I know the cause wasn't the capacitors. I don't remember what fixed it ultimately though. Need to track back a little in my repair logs...

[lezsimply]

Re: Computer PSU 5v drop

Other reading such 5v, 3.3v, 12v, -12v 5vSB are ok but the 5v shows only 3v. I just want to know what electronic component usually go out when 5v is dropping? I'm thinking about a DIY method on fixing this power supply. I think its not that complicated or is it? Thanks!

What I have said here is confusing what I meant was 3.3v, 12v, -12v and 5vsb are ok but not the 5v. sorry for the wrong input

Some friends told me to try and replace transistors which are attached to a heatsink that links to 5v, but I don't know which one. The best thing to do as of now is to look for datasheets regarding those transistors and see what characteristics they have. Thanks guys!

[crystalsercpn]

Re: Computer PSU 5v drop

What I have said here is confusing what I meant was 3.3v, 12v, -12v and 5vsb are ok but not the 5v. sorry for the wrong input

Some friends told me to try and replace transistors which are attached to a heatsink that links to 5v, but I don't know which one. The best thing to do as of now is to look for datasheets regarding those transistors and see what characteristics they have. Thanks guys!

What is the solution of this you got ? please share with me Thanks.

[lezsimply]

Re: Computer PSU 5v drop

what do usually fail when 5v go crazy. Its hard to remove components on this kind of power supply unlike the typical ones. I think they used a much strong lead on it. I use to remove bloated capacitor without problems but this one is kind of a tricky one.

@ganes
I haven't found any solution to this problem yet. Still waiting someone of experience on this. Hope someone will do. Let see.

[c_hegge]

Re: Computer PSU 5v drop

The 5V rectifier(s) could be at fault (which is what Th3_Un1qu3 was saying). It's attached to the secondary heat sink (the one closest to the output side). I think it's the one circled (although it might be the one below it). The 12V rectifier is almost definitely the one closest to the top of the pic. If you can remove the secondary heat sink, then see which order the bundles of wires are in. The rectifiers will almost definitely be in the same order. Note that there may be two 5V rectifiers. If so, the other one will be installed on the other side of the heat sink directly opposite the circled one. If there are two of them, then replace them both.

[lezsimply]

Re: Computer PSU 5v drop

Oh my bad Sorry but I didn't noticed unique's post honestly.. just read it now. I was waiting for someone to reply on my post yet I have overlooked it. Thank you very much c_hegge for mentioning it. I'll try it soon tomorrow and post some updates. Thanks again!

[JonathanAnon]

Re: Computer PSU 5v drop

Like the guys said above, it may just be something on the +5V rail ... inductor, fuse, capacitor, regulator, or fast rectification diodes... Only problem with those PC power supplies is that they are CRAMMED into such a small space.. But if you could trace back from the +5v output you may be able to get back to the rectifiers after the switch mode power transformer (i.e. and identify each of the relevant components). WITH THE POWER TURNED OFF, I would test all the components along that +5V line, starting with the rectification diodes.

Have you tried the same PSU with another board just to be sure that it's not shutting down because of a problem with the motherboard? If it was me, I would test it with another board before starting the troubleshooting process.

[senz_90]

Re: Computer PSU 5v drop

Good day, I have a Thermaltake 850 watts Toughpower power supply. I've tested it using a multimeter and I see 5v is dropping. It cannot boot my desktop pc anymore.

Other reading such 5v, 3.3v, 12v, -12v 5vSB are ok but the 5v shows only 3v. I just want to know what electronic component usually go out when 5v is dropping? I'm thinking about a DIY method on fixing this power supply. I think its not that complicated or is it? Thanks!

maybe just a bulged caps. use ESR meter to found it if that is no sign about bulged caps. also with off board test can give a exact result.

[lezsimply]

Re: Computer PSU 5v drop

Until now I cannot seem to find a way to remove the secondary heatsink without breaking it as it is really bound to the board. The leads used in this power supply is hard to remove. Already used 60 watts soldering iron. I think its not my soldering skill because I can remove any capacitor on a desktop motherboard. no bulging capacitor found. I think I'll be trying a 90 watts iron.

[senz_90]

Re: Computer PSU 5v drop

Until now I cannot seem to find a way to remove the secondary heatsink without breaking it as it is really bound to the board. The leads used in this power supply is hard to remove. Already used 60 watts soldering iron. I think its not my soldering skill because I can remove any capacitor on a desktop motherboard. no bulging capacitor found. I think I'll be trying a 90 watts iron.

60 Watt can desolder it? wowww. what a tough one..did you check all of parts connected to heatsink?? did you just desolder all three legs rectifier, maybe you forget to desolder the heatsink it self ? it's hard to check rectifier heatsinked when in circuit, maybe u can try desolder the transformer at first because you describe hard to remove the rectifier, as transformer removed, u can check that diodes in circuit to get more accurate result, after you make sure it was leaky, desolder it with all of your weapon and changes it . there is still one ways as i guess. if you can inserting your screwdriver to remove the bolt on diode, just desolder the 5V diode and replace it.

btw using flux may help you..