"POWER PC" ML915 350W power supply

[Newbie2]

I just recently got my hands on a brand new generic "POWER PC" ML915 350W power supply, which cost $20 CAD at a small local computer shop.

I could not positively identify the manufacturer of this PSU as there was no UL number to look up, and all the markings on the PCB (which were "HY", "HY0011", "ML915", and "ML 908B") turned up nothing informative to this PSU on Google. This PSU does sort of look similar to my Delta Power 450W PSU that I have in an older thread: https://www.badcaps.net/forum/showthread.php?t=7708

Here are its specifications on the sticker:
+5V = 20A
+12V = 14A
-5V = 0.5A
-12V = 0.5A
+3.3V = 16A
5VSB = 2.0A
Total = 350W (more modest than the typical 400W+ claims of other generic PSUs)

Here are some pictures of this PSU:




Three shots of the power supply.


Not many connectors coming from this power supply; there's just the 20+4 pin ATX motherboard connector, 4-pin P4 12V connector, four 4-pin peripheral power connectors, and just one SATA power connector (missing the 3.3V wire found on most better power supplies).


The label of this power supply.



Two overhead shots of the internals of this power supply.


The two "KDC" 560uf 200V primary caps in this power supply.


What consists of the transient filtering stage (nothing really), as well as the four diode treatment consisting of 1N5408 3A diodes.


The primary side silicon, consisting of a C5027 3A NPN transistor and two Fairchild-branded 13009 fast-switching NPN transistors, all in the familar TO-220 package size.


The three transformers in this power supply.


Another shot of part of the primary side of this power supply.


The secondary side capacitors; they are all "BH" brand, and the four blue 10mm caps are rated at 1000uf 10V while the two brown ones of the same size between them are 1000uf 16V.


The secondary side silicon, consisting of one MOSPEC F16C20C 16A power rectifier and two MOSPEC S20C45C 20A Schottky rectifiers, all in the TO-220 package size.


The "CG8010DX16" PWM chip in this power supply on the secondary side.


The single 80mm exhaust fan in this power supply is a "Legend" DF0802512SEMN, which I could not find any information on.


A view of the 80mm exhaust fan of this power supply.



Two pictures of the PCB underside of this power supply.

Regarding what might be the true wattage of this power supply, the 3A 1N5408 diodes on the primary side would mean that this power supply would only be able to pull in a maximum of 360W on a 120V AC line, which would actually be 252W assuming 70% efficiency (typical of cheaper PSUs). The silkscreen on the PCB states "F5AL/250VAC 230W" on it (visible in one of my pictures), and the fuse used in this power supply is indeed a 5A 250VAC fuse. Both these factors I found could indicate that a more honest rating of this PSU from the manufacturer would be around 230W, which seems reasonable considering the maximum amount of power this PSU could pull in from a 120V AC outlet judging from the diodes.

I do not plan on rebuilding or upgrading this PSU, as the cost for capacitors and other parts would be equal to that of a decently made higher-quality power supply. I purchased this PSU to put into my basic Athlon 64 X2 3800+ build if I ever sell it or give it away, as I have my rebuilt Delta Power 450W currently powering that and I want to keep that rebuilt PSU. I have not yet plugged in and turned on this "POWER PC" PSU, and do not plan to in the near future as I currently have no need for it.

Any comments on this "POWER PC" 350W PSU?

[c_hegge]

Re: "POWER PC" ML915 350W power supply

I had an identical-looking Sky 550W-P4. The Switching transistors exploded when I asked for 280W load

https://www.badcaps.net/forum/showpo...&postcount=110

[Newbie2]

Re: "POWER PC" ML915 350W power supply

I had an identical-looking Sky 550W-P4. The Switching transistors exploded when I asked for 280W load

https://www.badcaps.net/forum/showpo...&postcount=110

Interesting, other than the primary capacitors on my PSU being "KDC" 560uf vs. yours with BH 470uf, and my generic fan being branded "Legend" instead of your "HongGu" everything else is the exact same. I like how the basic label style is the same (funny how your Sky 550W claims to have two +12V rails).

Now I wonder which manufacturer is behind these cheap power supplies...

[c_hegge]

Re: "POWER PC" ML915 350W power supply

Now I wonder which manufacturer is behind these cheap power supplies...

HongKongFlyApart company, LLC

[Newbie2]

Re: "POWER PC" ML915 350W power supply

c_hegge would you happen to have any pictures of your Sky 550W PSU after you made it explode?

[PeteS in CA]

Re: "POWER PC" ML915 350W power supply

With those wimpy heatsinks, I/P and O/P rectifiers, I wouldn't use it higher than 200 watts, if that. It's a half bridge design (the two 13009s - originally Motorola's MJE13009, specifically designed for switching P/Ss), the smallest transformer is probably the base drive (maybe proportional drive, which can be self-oscillatory at power-off if not done right). The 2SC5027 is probably for the Stby O/P, probably a self-oscillating discontinuous flyback (aka "ring choke"), the medium-sized transformer being for that O/P.

[c_hegge]

Re: "POWER PC" ML915 350W power supply

c_hegge would you happen to have any pictures of your Sky 550W PSU after you made it explode?

https://www.badcaps.net/forum/showpo...&postcount=113

[momaka]

Re: "POWER PC" ML915 350W power supply

If you add the input filters and bigger output caps, I think this might be a better unit than your Delta Power.

[Evil Lurker]

Re: "POWER PC" ML915 350W power supply

Not too bad really. I mean yeah it is an ancient voltage mode controlled piece of shit but it can be significantly improved. First off he 13009 switchers are at least in a TO-220 package, that should help with maximum wattage. And the board appears to have been drilled and silkscreened for an actual bridge rectifier. I'd prolly upgrade the rectifier diodes (not a big fan of mospec) to something from ST and add on some sort of input filtering and replace the primary caps with something a tad bigger.. Just go to a PC shop and get a few old junk PSUs for parts.

[Newbie2]

Re: "POWER PC" ML915 350W power supply

I am now planning a slight rebuild of this PSU, but nothing too drastic like my Delta Power 450W. I am thinking of adding in the transient filtering stage components (two more Y caps, an X cap, and a coil), replacing the BH capacitors with better capacitors in for the secondary side, replacing the MOSPEC F16C20C 16A rectifier on the +12V rail with a new STTH2002CT (a small improvement) that I have leftover from a previous PSU rebuild, and replacing the 80mm exhaust fan with something better that I have in my collection of fans.

All the parts to be used will be either from what I already have laying around or salvaged from two dead PSUs I own, which are an Enermax EG301P-VE 300W and the infamous Bestec ATX-250-12E 250W (before you ask, yes it had a 5VSB meltdown). I will not invest any more of my hard-earned money into this cheap $20 power supply.

Does this sound good?

[c_hegge]

Re: "POWER PC" ML915 350W power supply

If you're just using parts you have laying around, then I'd say go for it. That's what I did (other than a rectifier and the caps) when I re-built my Rexpower PL-400

[Th3_uN1Qu3]

Re: "POWER PC" ML915 350W power supply

the 3A 1N5408 diodes on the primary side would mean that this power supply would only be able to pull in a maximum of 360W on a 120V AC line, which would actually be 252W assuming 70% efficiency (typical of cheaper PSUs).

Hardware Secrets has been pushing this myth for years, even though they never had the primary diodes die in any of those cheapies. Neither have i. Not even the wimpy 2A ones. 95% of the time the primary switching transistors blow up due to overheating and then take out the fuse, then there's the occasional failed secondary diode when the power supply shuts down gracefully.

The reality is that 3A is the typical rating of this type diode in its typical operating position, ie sitting flush to the board and with natural convection cooling. In this case they sit upright and are in the fan's path. They will do almost double their rating without failing.

[Newbie2]

Re: "POWER PC" ML915 350W power supply

Hardware Secrets has been pushing this myth for years, even though they never had the primary diodes die in any of those cheapies. Neither have i. Not even the wimpy 2A ones. 95% of the time the primary switching transistors blow up due to overheating and then take out the fuse, then there's the occasional failed secondary diode when the power supply shuts down gracefully.

The reality is that 3A is the typical rating of this type diode in its typical operating position, ie sitting flush to the board and with natural convection cooling. In this case they sit upright and are in the fan's path. They will do almost double their rating without failing.

If this is the case, then I have a reason not to replace those four 3A diodes with a new GBU6J 6A bridge rectifier that I have. I don't want to waste a good new component if the 3A diodes are adequate for that $20 PSU, since it probably won't take advantage of the higher rating of the GBU6J. My father, an electronic engineer, does agree with what Hardware Secrets says about that.

I might pull a proper bridge rectifier from one of the dead PSUs that I have.

[c_hegge]

Re: "POWER PC" ML915 350W power supply

^
If you have a better rectifier you can scavenge from a dead PSU, then by all means use it, but if not, don't sweat too much over it.

[Newbie2]

Re: "POWER PC" ML915 350W power supply

^
If you have a better rectifier you can scavenge from a dead PSU, then by all means use it, but if not, don't sweat too much over it.

Agreed.

I have a question for you guys here, how come these generic manufacturers like to solder the L and N wires from the power plug (that also happened on my Delta Power 450W), and in this power supply even the thermistor into the vacant spot where the coil for the transient filtering stage belongs. There are proper locations for those two wires and thermistor on the PCB and marked on the silkscreen, so why do they solder those two things into a different location?

[c_hegge]

Re: "POWER PC" ML915 350W power supply

It saves 1c

[shovenose]

Re: "POWER PC" ML915 350W power supply

It saves 1c

How does solder location save them money?

[momaka]

Re: "POWER PC" ML915 350W power supply

How does solder location save them money?

If they install the wires at their proper locations, then they would have to install additional jumpers where the coil is and maybe a few other places. This takes time and money (even if it's not much, it adds up when you make 1000 of these PSUs).

[Th3_uN1Qu3]

Re: "POWER PC" ML915 350W power supply

My father, an electronic engineer, does agree with what Hardware Secrets says about that.

If you're really rigurous then yes, the 3A diodes can be considered inadequate for the job. However, the reality is that they do just fine. I've tested some of them with a current source and they perform exactly like i said they do - almost double the rating.

Same goes for the "diodes-on-a-bracket" on 12v. They are 3A each so in theory the 12v rail would only do 6A, but they do 10A for years. What going with oversized rectifiers does improve is efficiency (lower voltage drop), but if you got the heatsink to cool them the marginal rectifiers they put in will work just fine. I do however recommend replacing them with better ones, as higher efficiency also means the primary transistors are stressed less and you get higher maximum power. 400W is possible from a pair of TO-220 13009s if you can get efficiency above 80%.

[Newbie2]

Re: "POWER PC" ML915 350W power supply

I've just rebuilt the PSU, however when jump-starting it with no load the +12V rail is too high at 13.50V, along with the +5V rail at 5.73V. The 3.3V rail is fine at 3.35V. I unfortunately forgot to get pre-rebuild voltage values, so I cannot compare these no-load voltages to what the power supply would've originally had.

I know that switching power supplies should not be run without a load and may not function properly without a load, so I want to ask would the voltages go down to within ATX specification (maximum 12.60V for +12V and 5.25V for +5V) if it were properly loaded?