Part 2: Hell Hath No Fury Like 1,000 angry pixies! Okay... so when last we looked in on our brave TinkerDwagon, he was about to... oh, would you look at that. He already has it apart. AND taking pictures.
Taking a look at the left side of the PCB, we can see an even bigger inductor than those we spied from the outside; one would expect this as the 12V rail is supposedly capable of delivering 73A/876Watts! And filtering that juice is... 8800uF of the cheapest Asian-manufactured electrolytic caps imaginable.
I mean,
"Yay! 8800uF of Low-ESR 105°Caps!!!" but
"Eeeehhhh...." on their choice of brand/product line.
Just as an aside: I know about this because I'm in the trade, but
"Cheap as F***" electrolytics are EVERYBODY'S dirty little secret when it comes to computer PSUs; even your prestige-brand gaming gear that comes in black chrome and aluminum extrusion has... cheap-ass caps. Some will argue it's simple economics of cost per 100K units, some will argue that it's deliberate to force turnover when they die. But they're just a fact of life.
(Not to be confused with cheap ass-caps, which is just an unfortunate byproduct of the corporate mentality)But right next to those cheap caps; what the hell is that... a copper heat-sink? NO! It is the freaking 12V Rail to the front panel!!!
Holy BLEEP!!!ing BLEEP!!!CRACKERS, MAN!I can actually believe in that carrying 80 amps without breaking a sweat. Without getting warm, even.
And would you look at that... 12ga bus wires for the 3.3V & 5V rails. Damn...
not too shabby. Not at all. I'm beginning to think this thing really was made to power a mining rig. I mean, there is some serious industrial-duty design in here.
Looking at the other side, we can see... NOT the cheapest possible electrolytics on the line-voltage side! I guess if you're going to cheap out on your caps, better to NOT do it on the side that has an open channel to
all the angry pixies. Next another massive inductor, some rectifiers on the ample heat-sinks, and
OH, MY GLOB!!! Is that a RELAY?!? SERIOUSLY? I am REALLY beginning to like this PSU! Next we get our first glimpse at the belly of the beast; lots of SMD here, but still lots of big heavy THS components to handle big current with ease... not the least of which is the other leg of that big honking 12V rail. Man, they are SERIOUS about getting that juice to the far side of the front panel unmolested.
You can also see the huge solder pads where the +12V & GND rails solder to the mainboard... just awesome. And there's a big old slab of silicone thermal pad there under the switching elements, to augment the heatsinks and wick heat away to that huge, thick metal shell.
Next up are overviews of the main PCB... here you can see the general layout, and grok in fullness all the delicious inductor pr0n. For as busy as it is, and how much space that 140mm fan displaces inside the cabinet, things are actually pretty tidy. And
Praise Ifni! Instead of hot-snot, they used silicone RTV when they needed to glue stuff down.
Next we can see a close-up of the huge chunk of copper they used to make the GND bridge to the front panel; not only is it a soldered pad almost 25mm square, it also has 3 screws through it! I think we found the source of that loose bit of suspiciously disc-shaped solder!
And finally... the business end of the thing. Here you can see all the breakout of all the sockets. All of the 5-pin sockets are wired and complete circuits for 3.3V, 5v, 12V and dual GND. All the 8-Pin sockets are 4+12V/4 GND. The 24-Pin socket for ATX power appears to be a proprietary pinout; the cable is not 1:1 from end to end.
If you look at the board, you'll see some spots populated with 100uF/16V electrolytics. There is 400uF worth on each of the 3.3V, 5V and 12V rails. C26 and C27 unpopulated are across the 5V and 12V rails; all other unpopulated spots are for the 12V rail. That's 1300uF left out, plus whatever they didn't put in C27!!!
I mean... yeah, of course it's not mission-critical. But it was good engineering to design in a "bank of filter caps" right at the end of the heavily-loaded 12V bus, with lots of small value caps to massively drop ESR right where it was needed most.
But either as a cost-cutting measure or due to shortfalls in supply chain, that clever filter bank never made it out the door.
I really feel a need to replace those missing caps; but they're a little bit of a bastard child and will need to be ordered. I have lots of caps that will fit in there at ~8mm diameter, but they need to be 11mm high or shorter to fit behind the panel, and every damn one I have of any useful value are 12.5mm high.
I do have oodles of these 470uF/16V ones left over from another project I think I can sneak in from the back side however... and maybe I'll touch up the soldering on the 12V rail.
But THAT is a story for another day.
mnem