Coolermaster Extreme Power Plus 550W design problem

[aanev]

I have many of this power supply with Active PFC, and first they start to smell and after that they stop working. I open it and smell comes from the positive high voltage just after the 220V rectify. They have Active PFC coil that is always very hot and start to burning, and after some time if coil burns there is one big mosfet that is failing short. So in my opinion there is some problem with the design,can someone tell me a way how to bypass this Active PFC part like in noname PSU, or what else can burn this coil, maybe main Capactitor that is measured good?

[c_hegge]

Re: Coolermaster Extreme Power Plus 550W design problem

The one thing that usually goes wrong with these is that the fans quit and the unit cooks itself. I assume the fans on these still spin freely?

[shovenose]

Re: Coolermaster Extreme Power Plus 550W design problem

Mine had a failed fan when I got it, after putting in a working fan it still smells. Same issue?

[aanev]

Re: Coolermaster Extreme Power Plus 550W design problem

It's not a fan problem, I think it is design problem by manufacturer, every second or third is failing same way. Even if you open it after 15minutes when it is still new and try to put finger on that PFC coil you'll see that it is very very hot..

[ben7]

Re: Coolermaster Extreme Power Plus 550W design problem

They are running them too hard. They also seem to be somewhat undersized!

[aanev]

Re: Coolermaster Extreme Power Plus 550W design problem

I'm running them on office pc with core 2 duo and onboard graphic that work on noname 300w psu without any problem.So is there any way to bypass this active pfc or add some resistor somewhere or maybe even short the coil or put a coil with higher inductance??
Maybe main capacitor is too low or too high in capacity foor that coil??
Question is more technical, because again I think it's design problem not usage problem or defective part.

[uligli]

Re: Coolermaster Extreme Power Plus 550W design problem

Mine has been working without issues more than one year, almost 12 hours every day.

[aanev]

Re: Coolermaster Extreme Power Plus 550W design problem

Is it possible to put serial resistor between rectifier and this choke for current limiting, so It will not burn? How to calculate resistance and wattage of this current limiting resistor ?

[Th3_uN1Qu3]

Re: Coolermaster Extreme Power Plus 550W design problem

Is it possible to put serial resistor between rectifier and this choke for current limiting, so It will not burn?

No. Well, perhaps... if you're willing to burn A LOT of power.

[everell]

Re: Coolermaster Extreme Power Plus 550W design problem

What brand and model. Need some pictures. Booster coil running too hot then causing FET to short is not an unusual problem. My OPINION,,,,the core material used is cheapo, the wire may be undersized, and you are expecting too much from what is there.

[999999999]

Re: Coolermaster Extreme Power Plus 550W design problem

BUT, is the coil burning then the transistor shorts, or was the coil just running warm then it burnt because the transistor shorted? Unless the coil solder joints are broken before the transistor shorts, I would try upgrading the switching transistors.

[everell]

Re: Coolermaster Extreme Power Plus 550W design problem

Every APFC circuit I have fixed had burnt coil and shorted FET switchers. Replacing the FET transistors did not solve the problem as the new FET transistors shorted.
The coil always showed some signs of being burnt, and the short was always near where the coil wire was soldered to the pc board. Measuring with an ohmmeter or DVM is useless because you can't distinguish between low resistance reading and shorted coil. BUT.....I purchased a Ring Tester....and without taking the coil out of the circuit, a shorted coil indicates short whereas a good coil has a good ring.

[ben7]

Re: Coolermaster Extreme Power Plus 550W design problem

BUT, is the coil burning then the transistor shorts, or was the coil just running warm then it burnt because the transistor shorted? Unless the coil solder joints are broken before the transistor shorts, I would try upgrading the switching transistors.

The dc resistance of the coil is low, so when the mosfet would short, there would be a large current in the coil. So large that the fuse will blow before the coil will even get hot.

[shovenose]

Re: Coolermaster Extreme Power Plus 550W design problem

I've come to the conclusion that these are simply crappy power supplies.

[everell]

Re: Coolermaster Extreme Power Plus 550W design problem

Here is a picture of two APFC coils in series in a Delta power supply. They were definitely burned, probably shorted. I tried winding new coils, but they also ran very hot. I was using cores from junked out psu's, so the core quality was probably very poor. I ended up completely replacing them with commercially made "booster coils". Still runs hot but has not burned up. I think there is not enough engineering done on these booster coils for long term service. Just get it out the door and sold. Then worry about heat problems later.

[Behemot]

Re: Coolermaster Extreme Power Plus 550W design problem

When some ppl said it is working fine, and some not. What is your mains voltage?? If 230 V, than the coil is not that much stressed as on 110/115 V on which it is at least two times as stressed.

[Wester547]

Re: Coolermaster Extreme Power Plus 550W design problem

^ In terms of the bridge rectifier but I'm not sure if that applies for the rest of the PSU, though 230V is definitely more efficient than 115V. I don't understand why these APFC coils run so hot? Are they all really that hot in every APFC PSU? Makes APFC PSUs look like an unattractive option which is sad considering how omnipresent they are today.

[cheapie]

Re: Coolermaster Extreme Power Plus 550W design problem

I don't understand why these APFC coils run so hot? Are they all really that hot in every APFC PSU? Makes APFC PSUs look like an unattractive option which is sad considering how omnipresent they are today.

I used to have an OCZ OCZ700MXSP ("ModXStream Pro" 700 watt, made by Highpower). It had APFC, and it ran fine on 120V. Then again, I don't think I was even drawing 200 watts...

Also, are you SURE it has APFC? Hardware Secrets says it doesn't have any PFC. Looking at their picture, I don't see any PFC either.

[Behemot]

Re: Coolermaster Extreme Power Plus 550W design problem

^ In terms of the bridge rectifier but I'm not sure if that applies for the rest of the PSU, though 230V is definitely more efficient than 115V. I don't understand why these APFC coils run so hot? Are they all really that hot in every APFC PSU? Makes APFC PSUs look like an unattractive option which is sad considering how omnipresent they are today.

The boost effect is being achieved through the coil, so yes, the lower the input voltage, the higher the stress on the coil to obtain 380-400 V.

[Nikochan]

Re: Coolermaster Extreme Power Plus 550W design problem

My sis had one of these, Cooler Master eXtreme Power Plus 550W (RP-550-PCAA-E2) to be more specific. She told me that it smelt bad and got very hot, so I replaced it with a Seasonic.

When I opened it up, aside from lots of cheapo Capxon caps, I saw this coil, glued between two heat sinks which was almost charred. It probably was the source of the smell. Other than that the PSU looked okay.

Recently, I've been thinking of repairing it by replacing the coil, but seeing this thread has made me realized that it probably has serious design problems, so perhaps wouldn't worth the effort.

Although, as PSU was in a working condition before I replaced it with a new one, I still want to give it a go. What I would like to ask is, is there a way to identify that coil? I don't know if it had markings on it showing the specs, as it got burnt they are no longer there. I'll try to post a picture of it.