What could cause this PSU to output 12.5V on the 12V?

[Pentium4]

So, the PSU in question is crap no doubt. It's a "Nift" branded L&C power supply that took out a motherboard due to the really high voltage on the 12V. I tested it and the 3.3V reads 3.3, the 5V reads 5.0 and the 12V stays right on 12.5V. What could be causing this? The caps look to be good but then again it's purely YC caps. Also just for fun, I posted a pic of 2 NIFT PSU's with the same exact label, but holy hell look at the different in build quality! They're both crap but they sure did improve it some (Don't mind the missing input cap on the right one, I ripped it off )

[budm]

Re: What could cause this PSU to output 12.5V on the 12V?

It is within spec, if the mother board cannot handle 0.5V higher on 12v LINE, that is not good


http://www.certiguide.com/apfr/cg_ap...owerSupply.htm

http://www.tomshardware.com/forum/30...hold-concerned

[Pentium4]

Re: What could cause this PSU to output 12.5V on the 12V?

Oh okay, 12.6V is the max, for some reason I thought that it was 12.5V. Still seems a little high though, what happened on the mobo was all the TK caps on the mobo bulged, and all the panny's lived

[rogfanther]

Re: What could cause this PSU to output 12.5V on the 12V?

I think you can find this psu in threads talking about "anodia" caps. I do not remember the brand under which it was sold, but they are, while not the best, not the worst either. Good for about 200 - 250W, tops.

[Pentium4]

Re: What could cause this PSU to output 12.5V on the 12V?

Yeah, all of them are YC but the same color as Anodia caps, so they're probably the same company. This one has 470uf 200V Input caps and a 4A bridge rectifier. It was powering an Athlon x2, 2 dvd drives, a GT430, 2 RAM sticks, and a TV tuner card. Pretty low load really. Think this thing could be upgraded to maybe a 300W? The transformer probably couldn't do much more than that, if at all.

[tom66]

Re: What could cause this PSU to output 12.5V on the 12V?

TK are just rebranded OSTs, I thought.

I like PSUs with high 12V. It's good, lower current draw, so in theory slightly more efficient in places. As demand increases, the voltage can drop - this is normal, some designs are like that.

[Pentium4]

Re: What could cause this PSU to output 12.5V on the 12V?

TK are just rebranded OSTs, I thought.

I like PSUs with high 12V. It's good, lower current draw, so in theory slightly more efficient in places. As demand increases, the voltage can drop - this is normal, some designs are like that.

Yeah that's true. Do you think it's worth improving? The output rectifiers are 20A, 30A, 30A, 5A. Not sure which ones are which but those are the specs of them.

[rogfanther]

Re: What could cause this PSU to output 12.5V on the 12V?

I would risk saying its quality can be improved with better caps. At least it has inductors in the outputs. Seems the other model , with just one row of caps, lacks these also.

Up to 300W I don´t know, but maybe assuring 250W with some reasonable stability ? Which was the motherboard that burnt ?

Just to register, most of the psus of the second type ( just one row of green caps ) I have seen around here, where dead when the fan stopped running, then they would cook the toroid inductor, and it would in turn cook the few caps the thing has.

[Pentium4]

Re: What could cause this PSU to output 12.5V on the 12V?

I would risk saying its quality can be improved with better caps. At least it has inductors in the outputs. Seems the other model , with just one row of caps, lacks these also.

Up to 300W I don´t know, but maybe assuring 250W with some reasonable stability ? Which was the motherboard that burnt ?

Just to register, most of the psus of the second type ( just one row of green caps ) I have seen around here, where dead when the fan stopped running, then they would cook the toroid inductor, and it would in turn cook the few caps the thing has.

Precisely, the fan seized up and it cooked. The motherboard if I recall correctly was a Biostar, but not 100% sure. I could at least add an X cap and maybe replace the bridge rectifier with a GBU606 just because I have so many of them lying around.

[rogfanther]

Re: What could cause this PSU to output 12.5V on the 12V?

Of ocurse, anything in it can be an improvement.

I have one like yours ( with that big bunch of green radioactive caps in the secondary ) waiting for a day I decide to try fixing its 5vsb as a learning experience.

[mariushm]

Re: What could cause this PSU to output 12.5V on the 12V?

Someone already said 12.6v is OK ... and it is, nothing wrong with it.

It's group regulated model, which means that as you put some load on 5v (around 2-3A), the 12v will slowly drift down towards 12v.

Problem is modern computers don't use 5V that much nowadays and this kind of psu was designed for the 5v days of the past.

[Th3_uN1Qu3]

Re: What could cause this PSU to output 12.5V on the 12V?

It's group regulated model, which means that as you put some load on 5v (around 2-3A), the 12v will slowly drift down towards 12v.

Wrong... If you put some load on 5v, 12v will go UP, and vice versa. This is likely an old design, tweaked to work better with modern computers. Under load you will find voltages to be within spec.

I remember Socket A boxes (which don't use 12v at all, except for the hard drive and optical drive) with cheapo PSUs where 12v would be over 13v. They ran like that for years.

[Pentium4]

Re: What could cause this PSU to output 12.5V on the 12V?

Thanks for the replies, good to know How hard would it be to add a fan controller? I took one out of a parted out SPI power supply.

[goodpsusearch]

Re: What could cause this PSU to output 12.5V on the 12V?

Does it use 13007 or 13009 switching trasistors?

[Pentium4]

Re: What could cause this PSU to output 12.5V on the 12V?

Does it use 13007 or 13009 switching trasistors?

It has a DFF2N65, and two D304X

[goodpsusearch]

Re: What could cause this PSU to output 12.5V on the 12V?

Transistors limit: 300watt max

2x470uF primary caps: (maybe) 300watt peak
But they could be fake... and real capacitance can be 330uF. L&C does that very often.

The power supply needs a second coil at the input AC filter and a second X capacitor.

I would not make the fan run slower with those heat-sinks and the general design.

[momaka]

Re: What could cause this PSU to output 12.5V on the 12V?

Oh okay, 12.6V is the max, for some reason I thought that it was 12.5V. Still seems a little high though, what happened on the mobo was all the TK caps on the mobo bulged, and all the panny's lived

TKs are crap and that's why they failed.
12.5V is a bit high but wouldn't kill them. That said, I don't like the 12V rail on my PSUs that high either. In my experience, all of my hard drives run hot when the 12V rail is either too high or too low. 11.90 to 12.30 is where I like/try to keep it.

[ben7]

Re: What could cause this PSU to output 12.5V on the 12V?

Try loading the 5v and 3.3v. The 12v might be poorly regulated. Also check how much ripple is on the power rails.

[Pentium4]

Re: What could cause this PSU to output 12.5V on the 12V?

I'd be happy to get 300W out of this thing. I'll test the YC input caps for capacitance and probably replace them with 470uf OST's because I don't want to waste my 560uf Panny's in an L&C. Yeah TK are pretty bad, I'd like to see more like 12.3V but at least it's still in spec

[Pentium4]

Re: What could cause this PSU to output 12.5V on the 12V?

So I was really busy at work today so I didn't have much time but I took out the "Sleeve Bearing" (no brand) fan and replaced it with an NMB-MAT, ahhh so much better It's at least 3 times quieter and don't have to worry about it failing any time soon.