Reviews - Death of a Gutless Wonder V: Uncool to the Max
Sample Provided by: N/A (By OklahomaWolf on Mon, May-12-2014)

Page 5 - Disassembly

First up, a fan shot. It's from Globe Fan, and it is... sigh. A sleeve bearing fan. That's the third thing the box was wrong about, and I do score against build quality when I see sleeve bearings. I don't like to see them in a power supply.

I don't know who built this unit, but here it is. I have to say I've seen worse. At least they used an actual fan connector rather than just soldering wires right to the board.

I, uh, think I just found the source of the light show. I'll give you a better look in a moment. Just let me get this board out of the housing first.

There is no line filtering at the AC receptacle, but I am pleased to see the additional heatshrinking around the wires to the mainboard, and around the solder tabs on the receptacle and switch. I really appreciate little extra touches like that.

And we have an actual plastic insulator, too. Usually, the gutless wonders leave that out. So far, I kind of like the OEM, whoever it may be.

Soldering, as is common for single layer boards, is excellent.

Now, we start seeing some cracks in the facade. I see two X capacitors, one coil, and only two Y capacitors. No surge suppression device. The AC transient filter is there but incomplete. That'll be a scoring hit.

That would be the standby controller in the lower right, there. It's a Viper22A from ST Microelectronics. No old two transistor garbage here... the OEM did the standby rail right. Even if I do believe 3A is a bit too much load for the rest of the parts on this rail.

All capacitors in the unit are Teapo, a second tier supplier for me. They could have gone much cheaper on capacitors and didn't, so I appreciate this move as well.

More minor but scoreable issues here. There is a provision for a fan control thermistor, but it is not being used. Shame on you, Coolmax. Now you have no excuse for that noise curve graph on the box.

Additionally, the output pi filters on all three main rails but the 3.3V are incomplete. We get the two capacitors on all three, but only the 3.3V gets the coil part of it too. That may or may not be why we saw 5VSB ripple in the 12V rail when the main power was offline.

Speaking of the 5VSB, usually you will see it running through its own dedicated Schottky in a TO-220 casing or similar. This unit uses a big old ordinary 5A Schottky diode, seen in the shot.

That's a Weltrend protection IC, right there. Not that the protection was able to save this unit from doom.

Another view of the output side for you. The unit could probably do with a little more coil whine squelching glue in there, but I'm just amazed a unit this cheap even has any.

Ok... here's the damage again. R46 has a hole blown in it and is no longer measuring the correct value. R36 is vaporized. C21 got burned by R36. The unit uses double forward converter technology and one of those diodes (the one by R46) is failed shorted. IC4, the unit's CM6805 PWM controller, is blown to glory.

This is the primary side heatsink. Decent amount of cooling potential on this one. On this side of it, we see the PFC diode and the IXTO22N50P PFC MOSFET. Both parts test good. We also have a GBU10K bridge rectifier that tests good.

All parts are insulated from the heatsink and mounted with thermal grease. Again, things the OEM could have cheapened out on but didn't.

On the other side of the heatsink, we find two MDP13N50 main switchers. One of which, the one on the right, is fried. These are decent quality parts, too.

Ok, now we know the real story. This is clearly not intended by the engineer who designed it to be a 500W unit. On the left, we have the only 12V Schottky in the unit, an S30D60C. It's fried. That's right, the 12V rail on this unit is rated at 4A above the part that supplies it. I don't know how this thing passed cold testing. I don't know how 80 Plus cleared it, unless Coolmax or the unknown OEM cherry picked a unit to send them they knew would pass, because just grabbing one off the shelf at random, from what I'm seeing, you'd be as likely to have one fail as pass.

The other two Schottkys are S30D40C, and supply the 5V and 3.3V rails. Plenty of capacity there.

Either this unit is being overrated by Coolmax or by their OEM. It's an acceptable quality 400 watt unit. It is NOT a 500 watt unit in any way.

How long do I figure this unit would hold up for you? Keep it below 400 watts, keep it cool, and you're looking at probably a good three years or more. 500 watts? A day if you're lucky.

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