Ständig S-1502D V2 Adjustable PSU (aka cheapo ebay power supply)

[bdlow]

Bought an "Adjustable Digital Power Supply 0-15V 1-2A S 1502D DC Power Supply BLUE LED" on ebay, $55 + delivery.

Unsurprisingly, turns out it's got a couple of problems, at least one of which is potentially fatal:

• 2 pin power cord, yet not double-insulated (ref. photos)
• not actually current limiting, rather over-current cutout / electronic fuse
• the banana sockets are poorly made, the "earth" and +ve terminals are not drilled out fully (banana plugs don't fit properly)
• there's an occasional disconcerting "pop" when powering on - I'm guessing the power switch won't last long

You Get What You Pay For. Due at least to the first two issues, I'm returning the unit I bought and will be ponying up the dollars for a hopefully better quality unit.

Photos of the innards:
https://plus.google.com/117899757503271140519/posts/B7bdnhp5FER


Rgds,
Ben

[T4P]

Well you paid too much money for a heap of S*!@
But anyway, if it wasn't for the over-current cutout thing i would have done some easy mods (2pin because some places only have well 2pins but have no double insulation rule, you can put 2pin sockets but to place the double insulation logo you must abide by it.)
3pin iec socket
buy some new banana sockets
fit a proper switch

ANYWAY.

[electronupdate]

Hi Ben,

I spent a bit more $99 on this one... I tore it down and it looks a bit better:

<iframe width="420" height="315" src="https://www.youtube.com/embed/A3yZTSAd8YE" frameborder="0" allowfullscreen></iframe>

It's interesting that there is so many supplies coming out of China which have a similar faceplate, but the internal contruction is so wildly different!

[bdlow]

Well, when I contacted the seller re. refund, he offered the upgrade to a model "305D" for an extra $40 or so (i.e. total $99 + delivery).

I accepted, and here's the result:
https://plus.google.com/photos/117899757503271140519/albums/5791248625413852001

It has a very similar external appearance to electronupdate's device and superficially similar arrangement internally, however the innards are not at all the same. This unit has three power transistors, the heatsink has ventilation holes, the control board is clearly different. The chassis on the 305D doesn't have a top brace, but otherwise seems similar (similarly flimsy but as expected for the price, that is :-). A big step up from the cheaper and nastier unit is that it's actually earthed properly.

It's nominally 0-30V / 5A current controlled, with two current ranges (0-1A and 0-5A). It maxes out at around 3.5A (terminals shorted) but that's fine for my purposes. Ripple and noise is under 200mV when driving 10V at 3A. I can confirm this supply also drops out of regulation when powering off and on.

I tested this unit by leaving it running a 1A current controlled load for a couple of hours, and also with a 3A load for about an hour, it coped ok (got warm but no fires and kept going).

Only real annoyances are the control pots are not very smooth in their adjustment (particularly the "fine" voltage control) and the binding posts are a bit loose. Both could be fixed if I cared enough...

Overall, I'm happy with this unit, for the price.

[T4P]

3.5amps? What's the voltage you tested it at? Make sure you short it out with 18AWG wire (I'm asking that because my 30V-3A PSU does 5amps oddly)

[LaurenceW]

Hi, Simply SHORTING the output of a power supply to "see what it goes up to" may give you a misleading result - the circuit might employ some sort of "foldback" current limiting, whereby the electronics actually drops the current when it detects it is basically driving into a short circuit. This can hugely reduce the series pass transistors' dissipation.

Try driving a "real" load, instead. 12V car bulbs are pretty cheap to string together.

[saturation]

For details on a comprehensive tests for PSU see:

http://cp.literature.agilent.com/litweb/pdf/5952-4190.pdf

[bdlow]

I retested the 305D PSU with two 21W 12V automotive globes in parallel (the biggest load I have to hand). The PSU went into current limiting mode at around 4.2 A (I suspect with the 3.5 A limit reached earlier, I had not cranked the 'fine' current limit right up), at about 18.5 V. I got the same current limit with the output shorted - i.e. there appears to be no foldback limiting.

I haven't done any tests for line or output regulation, etc; maybe later :-)

[LaurenceW]

Then I am afraid, my friend, the only thing on your power supply which goes up to 5A is the label...