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PC Power Supply Discussion Troubleshooting and discussion of computer power supplies

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  #1  
Old 07-02-2013
jack-o-bytes jack-o-bytes is offline
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Default Max Load 422w. Surely this is unsafe?

Hey everyone, Check out this for a cheap dodgy power supply. It came with a case that I bought. I have been running it as well tbf and recently it has finished its self off. It did well not to take the computer with it tbh.

Here are some shots of the inside that I took. Very large photos.














Now the dangerous part is the plugs on the back.

One take this kind of plug
the other takes this kind of plug

Now thats all well and good if you use the plug on the first image. However if you use the plug on the second link then that leaves the pins on the first type exposed to anyone that goes round the back of the computer. Now as you can see from the inside shots of the back of the plugs they are just connected with wires. That means that they would be totally live to anyone that may happen to put their hand round the back of the computer??

Jack-O-Bytes
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Old 07-02-2013
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Let's see now...

From the input, over the primary, and to the secondary, we have:

- Two Y-caps, dodgy NTC, no heatshrink on the fuse, ultra-thin input wires
- 2A diodes in the rectifier bridge
- Bottom of the barrel primary caps
- Can't really see, but probably 13007s as primary choppers, BEST-CASE scenario
- Old half-bridge + flyback design
- Laughable heatsinks
- EI-28 (at best) primary transformer advertised as ERL-35
- Can't quite see the secondary rectifiers, but somehow feel confident they're 12A FR diode for 12V, 20A SBR for 5V and 16V SBR for 3V3 rail.
- Laughable regulation coils on the secondary
- ONE WHOLE filter cap per rail with no coils/chokes
- Bottom of the barrel secondary filter caps
- Thin output wires (they say 20AWG, but look like 22s)
- Bottom of the barrel fan with no fan control
- PCB not even screened for anything more substantial, so it's a ground-up planned-crappy PSU

As for the dual power plugs on the back, they're meant to be used as pass-through. The female plug is meant to be connected by a standard cable to the mains outlet, and the male plug is there for you to use an extension/UPS-type cable, to connect your monitor.

And yes, if you somehow found a mains cable with a female connector on it's end, and plugged into the male connector meant for pass-through, you could very well electrocute yourself when touching the prongs on the female connector.

Welcome to mass-produced garbage.

Tens, if not hundreds of thousands of these (or similar) are sold each day worldwide.
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Old 08-26-2013
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Wow you really do know your stuff haha I would love to learn that much about this sort of thing thanks for looking at it
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Old 08-26-2013
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Oh, no prob, I see something very similar on a daily basis, in worrying amounts. It's still legal to sell garbage such as this where I'm from, so most people just go for what's cheapest.

I work as a service/electronics tech at an IT company, so I'm used to dealing with people's inability to comprehend the importance of a decent PSU... Though I'll never accept it, of course.

Chuck that thing where it belongs (garbage), and breathe a sigh of relief for doing yourself and the rest of the world a favor.
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Old 08-27-2013
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Those Y caps are definitely not safety approved. Neither is that NTC Thermistor. And those cheap glass fuses almost always explode when they fail. If this were to ever fail, it would probably shoot some sparks out the back.

Also, notice the QC stickers stuck to the primary caps? One says "B" and the other says "A". At first I thought they had a two level QC system, but then I noticed the A sticker is actually overlapping the B sticker, meaning it was put on later. Strange.
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Old 08-27-2013
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Quote:
Originally Posted by 370forlife View Post
Also, notice the QC stickers stuck to the primary caps? One says "B" and the other says "A". At first I thought they had a two level QC system, but then I noticed the A sticker is actually overlapping the B sticker, meaning it was put on later. Strange.
Makes perfect sense to me. "A" means it's guaranteed and "B" means it's the Bang variety, so it's been QC guaranteed to go bang!
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Old 08-28-2013
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Yeah those "Y caps" are probably just regular old 0.1uF ceramic discs. So common in low end stuff like Sun Pro (Not saying this is a Sun Pro)

I doubt it has anything lower end than 13007's, and that fan probably runs at full speed all the time which would help it out a little.

Those input caps are most likely 220uF, interesting, never seen that brand before.

Looks like that 12V diode is actually 20A, I would except 16A or lower

It looks like an "iMicro" PSU.

Look at how close those hot minimum load resistors are to the caps, surely that would cook them in no time.

Can you post a label shot?

Oh, and one last thing....hooray for the efficient and reliable two transistor 5VSB!
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Old 08-30-2013
jack-o-bytes jack-o-bytes is offline
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Here is a shot of the label. It is a DRAGON power supply haha :P
Is there any redeeming features in it haha?
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Old 08-30-2013
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The label just confirms it's a POS :P
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Old 08-30-2013
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Quote:
Originally Posted by jack-o-bytes View Post
Is there any redeeming features in it haha?
It can serve as a paperweight I guess.
Or as a source of components for small electronics projects.
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