12 V 180 W power supply.

I often use various power supplies at work, mainly to power video surveillance systems. I mostly use products from one well-known company, but their prices are pretty steep these days, so I wanted to try (and test) an alternative high-power 12 V power supply.
Read on for the description, photos, and conclusions.

I should mention that I’ve had similar power supplies come my way before (including for repair), but they were lower-power models. This time I wanted to see what’s inside a more powerful version of this type of power supply.

The power supply comes in a little white box, though all power supplies of this type come in identical white boxes :).


The case is standard too, with a perforated cover.
Dimensions: 198 × 99 × 42 mm
You can see a bent corner of the case in the photo. It looks like it took a knock in transit, although I didn’t see any signs of impact on the packaging. Let’s say the power supply passed an extra stress test.


There’s a label on the side with the power supply’s specifications.
Under the label are three screws: two secure an intermediate aluminum spacer, and one holds the diode assembly against it.


A terminal block for connecting the wires is mounted on the end.
The terminal block has a very convenient cover. Next to it are a trimmer for adjusting the output voltage and an LED indicating that the power supply is running.
This is all pretty typical of power supplies of this type, but I don’t want to just post photos, so here are a few comments. :)


Here’s the overall view of the power supply’s internals.
The power transformer’s markings are visible in the photo. Oddly enough, it’s marked 12 V, 16.5 A, not 15 A as stated on the power supply label.
There’s no power factor correction in this power supply.


The power supply uses a classic half-bridge topology, the same approach used in most computer power supplies, first AT and later ATX.
The photo shows two power transistors J13009, a PWM controller TL494, an isolation transformer with a current-sensing winding, and the surrounding components.


Here you can see the power rectifier assembly MBR30100, the inductor, and the 1000 µF × 25 V output smoothing capacitors.


The power supply uses the ever-popular TL494CN PWM controller, probably second in popularity only to the UC384x.
The circuit design is as classic as it gets, and there’s tons of information online about repairing power supplies of this type. That’s a plus because they’re easier to repair, but also a minus because I’d have liked to see something more modern. For me, it’s probably more of a plus.
I won’t draw any conclusions about whether the controller installed in this power supply is genuine. The main thing is that it works.


The power supply has a full input power filter, with no specially trained jumpers. You can also see the 110–220 V input voltage range switch (although I’m more used to seeing 115–230 V; in practice, there’s no difference).
It’s best not to touch this switch. If you plug the power supply into a 220 V outlet while it’s set to 110 V, it’s guaranteed to fail.


Overall view of the board. There aren't many unpopulated component positions (apparently, it's simply a universal PCB). There's a spot for a fan connector, so I can even imagine this board being used in a higher-power supply with active cooling. The installed transformer, marked 200 W, supports that idea.


The board is single-sided, and the soldering is quite good. The flux has been cleaned off, so no complaints there.


Actually, there is one complaint: a small blob of solder stuck under the PWM controller.


The input filter capacitors are Nippon Chemi-Con (at least, that's what they say on them), and their capacitance came as a surprise.
They're marked 220 µF and connected in series, giving 110 µF in total. That's a bit low for a power supply of this rating; usually, it's a good idea to allow at least 1 µF per watt of output power.
But when I measured them, I was very surprised: each capacitor was around 340 µF, so the two in series came to 170 µF. This is the first time I've seen capacitors with such a large deviation—and in the positive direction, too.
By the way, these capacitors are rated for 250 V, not 200 V as is usually the case in similar power supplies.


The output side is a little more straightforward: the whole bank of capacitors (five in parallel) adds up to 5500 µF. A +10% tolerance is perfectly normal for new capacitors.
I usually prefer to size output capacitors at 1000 µF per amp of output current, but that's with some headroom. In practice, the output capacitance in this power supply is quite sufficient. The capacitors are rated for 25 V; I'd use 35 V ones, but considering that computer power supplies often use 16 V capacitors on the 12 V rail, 25 V is perfectly reasonable.




And here's a comparison of the two power supplies: the 180 W unit under review and a 12 V 150 W Mean Well.
They're the same size, but their circuit designs are radically different, so comparing their performance isn't entirely fair.
I'll just say that this Mean Well costs two and a half times as much.


Summary.
Pros.
Quite good overall build quality and component selection.
Decent load performance.
Good value for money.

Cons.
The pad for mounting the power diode assembly is poorly finished.
Still, it's best not to run it at 100% load for extended periods.
The components are outdated, but this design has stood the test of time, so I wouldn't call that a serious drawback.

My opinion.
This power supply is perfectly usable. As always, I recommend choosing a power supply with some headroom. For the price, a 180 W power supply seems pretty good to me.
I'd replace the output filter capacitors with 1000 µF, 35 V ones; I think that would improve reliability. Overall, though, this power supply left a pretty good impression.

This power supply was provided free of charge by the gearbest store for review and testing.

P.S. In this case, it's more expensive on Banggood :)