How good or bad is this little power supply

[sam_sam_sam]

Here are two photos please tell me what you think about this little power supply

[sam_sam_sam]

Re: How good or bad is this little power supply

What do you think of this little power supply

5 volts at 300 mill-amps

[ReeceyBurger123]

Re: How good or bad is this little power supply

Soldering is shite matey, got image of the top side ? Also whats it rated for ?

Edit just seen you uploaded top side images as I replied lol. Looks quite rubbish tbh, could you get better images ?

[budm]

Re: How good or bad is this little power supply

Looks like One-Transistor switcher (I can only see one 3-leg DEVICE), no main fuse or fusible resistor that I can see.
Not much of the Creepage/Clearance between Line and Neutral. Cannot tell if the transformer is double insulated or not.
What is the AC Input rating?

[mariushm]

Re: How good or bad is this little power supply

For 5v @ 300 mA , it's a reasonably well built power supply.

Yeah, it looks like one transistor power supply but at least
* there is some optical isolator for feedback and adjusting output voltage, i've seen adapters that used a 5.6v zener diode as protection for maximum voltage and otherwise no feedback.
* the capacitors are at least from a known brand (but not a great one) and based on size they seem reasonably large enough,
* there is some decent separation between mains side and the secondary side
* there is a beefy Y capacitor between primary and secondary and it looks like it's safety rated and not just some random y capacitor
* bonus points for using a proper bridge rectifier instead of 4 separate diodes
* not so great that it doesn't use a proper fuse, but bonus points for using a proper resistor (and i think oversized) as a fuse

There are certainly much worst power supplies for that 5v @ 300mA out there, so I voted "use with caution".

[Khron]

Re: How good or bad is this little power supply

Actually, i think this thing has an IC switcher - the TO92 visible there is actually the xx431 that's part of the feedback.

The chip's actually obscured by one of the CapXons (right-most) in the primary - you can see its black underbelly through a separation slot, from the underside of the PCB.

The primary rectification is actually a 4-diode job, hidden under the left-most CapXon - most definitely NOT a bridge rectifier (the chip's the PWM).

That being said, the actual quality (and/or quantity) of the insulation INSIDE that diddy little transformer is the big question. After seeing oh-so-many teardowns of cheap crappy USB power supplies and whatnot, on BigClive's youtube channel... **shudders**

[budm]

Re: How good or bad is this little power supply

Ah, I see all those parts under all those caps now.

[stj]

Re: How good or bad is this little power supply

if i wasnt busy running away, i would re-solder the entire pcb!!

[budm]

Re: How good or bad is this little power supply

You should do safety test to see how it is, check it between DC jack and safety GND.

[kc8adu]

Re: How good or bad is this little power supply

fuse resistor against the filter cap.i can see this burning through the jacket and arcing if it has to blow.most of these cheap things have some sort of fatal flaw.

[sam_sam_sam]

Re: How good or bad is this little power supply

Thanks for all of your feed back
I have decide to just use them for part
This power supply has one thing going for that is it has a usb connector on it
This power supply look to me like an acadent waiting to happen
I have seen 5 volt at 500 mini-amp power supply's look better than this
I only paid $5.00 each for them it was the usb connector that I was after any ways

[stj]

Re: How good or bad is this little power supply

$5 is a lot, it looks like a $2 ebay job.
infact some of those look pretty good!

[zx8401]

Re: How good or bad is this little power supply

The pcb gap under the transformer looks decent, the emi capacitor look decent.
Its only 300ma so i dont expect it to get too hot.
It has the typical tl431 and optocoupler feedback so its not totally unregulated.
And an i.c pwm chip is being used, better than two transistors.
I would use it but not expect a lifetime use.
I would clean the pcb before use, that crap could leak power or help flashover.