Author Topic: Dirty cheap Chinese 12V 30 Amp power supply and its build quality  (Read 7886 times)

0 Members and 1 Guest are viewing this topic.

Offline FireFlower

  • Regular Contributor
  • *
  • Posts: 129
  • Country: fi
  • Wish had a cabin in Lappland
So if you ever come across to this: http://www.ebay.com/itm/172031363750 (all power supplies cost same).

Ordered one less than 13€ and opened it, looked inside, braced myself for flashy magic smoke but that darn worked!

Well anyway it is sold as 220Vac unit but its main capacitors (2) are rated for 250V (should be 400V), 680µF 105C, made by Rubicong   :--
Well anyway output capacitors (3) are rated for 25V 3300µF 105C made by ThongX  ???
Also bridge rectifier is supposed to have a heatsink according to PCB but mine is missing  :--

All other ElCaps are made by ThongX.

And then soldering quality is great because they clearly have a wave soldering machine! Bad news is all components are trough hole and some component legs are very long so I have about 0.1 - 0.2mm clearance between mains and ground because somebody didn't cut the leg.

Otherwise design seems to be pretty okayish for cheap chinese  power supply.

Pics:
http://hal.garde.fi/~fireflower/kuvia/projektit/kotostyskone/20160502_001.jpg
http://hal.garde.fi/~fireflower/kuvia/projektit/kotostyskone/20160502_002.jpg
http://hal.garde.fi/~fireflower/kuvia/projektit/kotostyskone/20160502_003.jpg

So do you think it is worth of 12,5€? :D
« Last Edit: May 02, 2016, 08:03:04 pm by FireFlower »
 

Offline rob77

  • Super Contributor
  • ***
  • Posts: 1848
  • Country: sk
Re: Dirty cheap Chinese 12V 30 Amp power supply and its build quality
« Reply #1 on: May 02, 2016, 08:18:30 pm »
i bet the two 250V capacitors are in series - it's a pretty common in ATX PSUs to have 2 x 200V cpacitors in series for 220-240V mains,  and for 120V mains the bridge rectifier is wired as voltage doubler with those 2 capacitors. that way you have the same PCB for both 240V and 120V versions - only a wire jumper is a difference.
 

Offline nctnico

  • Super Contributor
  • ***
  • Posts: 18949
  • Country: nl
    • NCT Developments
Re: Dirty cheap Chinese 12V 30 Amp power supply and its build quality
« Reply #2 on: May 02, 2016, 09:03:50 pm »
Rubicong  :-DD  :-DD  :-DD
Still it is amazing -no- mind boggling they manage to build a 360W PSU at this price point and make money.

edit: typo
« Last Edit: May 02, 2016, 09:23:25 pm by nctnico »
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline AF6LJ

  • Supporter
  • ****
  • Posts: 2903
  • Country: us
Re: Dirty cheap Chinese 12V 30 Amp power supply and its build quality
« Reply #3 on: May 02, 2016, 09:09:30 pm »
So let me guess the MTBF is measured in weeks.

I should add; anybody taking bets on how many minutes that thing will survive at full output before it bursts into flames?


Sue AF6LJ
Test Equipment Addict, And Proud Of It.
 

Offline suicidaleggroll

  • Super Contributor
  • ***
  • Posts: 1455
  • Country: us
Re: Dirty cheap Chinese 12V 30 Amp power supply and its build quality
« Reply #4 on: May 02, 2016, 09:18:54 pm »
So do you think it is worth of 12,5€? :D

Depends on what it's powering when it dies and takes out everything plugged into it.
 

Offline Delta

  • Super Contributor
  • ***
  • Posts: 1225
  • Country: gb
Re: Dirty cheap Chinese 12V 30 Amp power supply and its build quality
« Reply #5 on: May 02, 2016, 10:11:02 pm »
So let me guess the MTBF is measured in weeks.

I should add; anybody taking bets on how many minutes that thing will survive at full output before it bursts into flames?

Only one way to find out!  Maybe FireFlower will be kind enough to put a decent load on it (some car headlamp bulbs would be ideal) and leave it running!
« Last Edit: May 02, 2016, 11:05:06 pm by Delta »
 

Offline Delta

  • Super Contributor
  • ***
  • Posts: 1225
  • Country: gb
Re: Dirty cheap Chinese 12V 30 Amp power supply and its build quality
« Reply #6 on: May 02, 2016, 10:16:09 pm »
Bollocks to it, I've just ordered one myself!  ;D

£9.67!  I can't even get three pints for that!*

Estimated delivery is Tue, May. 17–Thu, Jun. 09 (!), so plenty of time to plan some testing!



*I can in my local boozers, but not in the town centre...
 

Offline rx8pilot

  • Super Contributor
  • ***
  • Posts: 3565
  • Country: us
  • If you want more money, be more valuable.
Re: Dirty cheap Chinese 12V 30 Amp power supply and its build quality
« Reply #7 on: May 02, 2016, 10:49:33 pm »
I cannot support these things.

Saving money by potentially exposing yourself to deadly flaws? Risk blowing up the powered device? Noise? Ripple? Stability? Safety?

I would love to see turn-on overshoot
Switched into a capacitive load.
Running anywhere near 30A for 5-10minutes (measuring noise up until it fails)
Watch it with thermal camera  - guessing the bridge will be getting warm enough to melt the leaded solder.

I am sure there are more fun things to observe, but it would require the supply last long enough.
Factory400 - the worlds smallest factory. https://www.youtube.com/c/Factory400
 

Offline AF6LJ

  • Supporter
  • ****
  • Posts: 2903
  • Country: us
Re: Dirty cheap Chinese 12V 30 Amp power supply and its build quality
« Reply #8 on: May 02, 2016, 11:02:33 pm »
So let me guess the MTBF is measured in weeks.

I should add; anybody taking bets on how many minutes that thing will survive at full output before it bursts into flames?

Only one way to find out!  Maybe FireFlower will be kind enough to put a decent load on it (some car headlamp bulbs would be ideal) on it and leave it running!

I am for the most part fearless; but that thing scares the Shit out of me.
Sue AF6LJ
Test Equipment Addict, And Proud Of It.
 

Offline MrSlack

  • Frequent Contributor
  • **
  • Posts: 880
  • Country: gb
Re: Dirty cheap Chinese 12V 30 Amp power supply and its build quality
« Reply #9 on: May 02, 2016, 11:07:11 pm »
Throw it away!

I had something similar from China about 3 years ago. 12v 2A rated to run some LED lights on my desk off. I paid I think £4.20 including shipping for one supply. It lasted an entire day before it blew a MOSFET and then one of the caps blew. Great safety feature there. It was running flat out at 2A however. Turned out that it was entirely dry of heatsink spooge. Much worse than the one you have.

The capacitors were Rudoykon carefully italicised which is just as stupid a brand rip off. Also interestingly, the charred remains of the capacitor pointed to it actually being a smaller unit inside a big can. Couldn't see the internal capacitor voltage or rating - no wrap on it. Never seen that before!

Replaced it with an TRACO one from RS for about £20. Still works today. Switching noise is horrible though and it's interfering with my RF experiments and scope something terrible.
« Last Edit: May 02, 2016, 11:08:50 pm by MrSlack »
 

Offline klunkerbus

  • Supporter
  • ****
  • Posts: 160
  • Country: us
  • Electrical Engineer (retired early)
Re: Dirty cheap Chinese 12V 30 Amp power supply and its build quality
« Reply #10 on: May 02, 2016, 11:15:18 pm »
I spend a lot of time on a forum for a great 3D printer kit that doesn't come with a 12V power supply. People are always searching out the cheapest 12V 30A MeanWell knock-off that they can. I'm sure there's countless different manufacturers of these power supplies, but from what I've seen, they're certainly a crap-shoot.  They end up working fine for some, but others complain about the fan going bad, or the power supply giving up after a few days to a few weeks of operation.  I'm sure they're not able to withstand the full rated load that people assume they can draw, or on a 3D printer, the heat bed cycling on and off.  That'll continually and instantly be swinging the power supply from low-load to full-load.

On the plus side, over the two years I've supported that forum, no one has ever reported a failed power supply that also took out whatever was connected to it.
 

Offline ez24

  • Super Contributor
  • ***
  • Posts: 3092
  • Country: us
  • L.D.A.
Re: Dirty cheap Chinese 12V 30 Amp power supply and its build quality
« Reply #11 on: May 02, 2016, 11:28:27 pm »
Ordered one less than 13€ and opened it, looked inside, braced myself for flashy magic smoke but that darn worked!

What worked?   Turned it on and got 12v at the terminals?  Or did you load it at 30 amps (my guess not ).   Maybe ok for 2 amps ?
YouTube and Website Electronic Resources ------>  https://www.eevblog.com/forum/other-blog-specific/a/msg1341166/#msg1341166
 

Offline MrSlack

  • Frequent Contributor
  • **
  • Posts: 880
  • Country: gb
Re: Dirty cheap Chinese 12V 30 Amp power supply and its build quality
« Reply #12 on: May 02, 2016, 11:29:32 pm »
It's not about how much, but about for how long.
 

Offline Brumby

  • Supporter
  • ****
  • Posts: 9816
  • Country: au
Re: Dirty cheap Chinese 12V 30 Amp power supply and its build quality
« Reply #13 on: May 02, 2016, 11:31:56 pm »
I only use those things for LED strips.
 

Offline GEuser

  • Frequent Contributor
  • **
  • Posts: 501
  • Country: 00
  • Is Leaving
Re: Dirty cheap Chinese 12V 30 Amp power supply and its build quality
« Reply #14 on: May 03, 2016, 12:31:32 am »
Op , Turn on some ShortWave recievers and see what you think about them then .
Soon
 

Offline blueskull

  • Supporter
  • ****
  • Posts: 13272
  • Country: cn
  • Power Electronics Guy
Re: Dirty cheap Chinese 12V 30 Amp power supply and its build quality
« Reply #15 on: May 03, 2016, 12:49:39 am »
Building quality is bad, but the design is ingenious. Self resonant LLC topology provides start up without the cost of an auxiliary power supply, then the self oscillation is disturbed and controlled by a gate/base driving transformer, which is controlled by secondary circuitry. This saves the cost of expensive high side gate driver IC (these things sell for more than $1 each, which is absolutely unacceptable for LED power supplies), and eliminates the opto coupler. As a bonus of the soft switching topology, it saves a second EMI filter which is usually needed for this power level.
 
The following users thanked this post: SeanB

Offline FireFlower

  • Regular Contributor
  • *
  • Posts: 129
  • Country: fi
  • Wish had a cabin in Lappland
Re: Dirty cheap Chinese 12V 30 Amp power supply and its build quality
« Reply #16 on: May 03, 2016, 07:21:39 am »
Ordered one less than 13€ and opened it, looked inside, braced myself for flashy magic smoke but that darn worked!

What worked?   Turned it on and got 12v at the terminals?  Or did you load it at 30 amps (my guess not ).   Maybe ok for 2 amps ?

Turned on and put 5A (60W halogen 12V bulb) load and was fine.

Yeah now I looked seems like caps are in series, but I will change all caps to some decent brand and see what happens :)
 

Offline chris_leyson

  • Super Contributor
  • ***
  • Posts: 1383
  • Country: wales
Re: Dirty cheap Chinese 12V 30 Amp power supply and its build quality
« Reply #17 on: May 03, 2016, 08:50:41 am »
That transformer looks a bit on the small side for 360W, by the look of things I would guess it's a half bridge converter rather than push-pull. Scary  :scared:
 

Offline djQUAN

  • Frequent Contributor
  • **
  • Posts: 253
  • Country: ph
    • My DIY website
Re: Dirty cheap Chinese 12V 30 Amp power supply and its build quality
« Reply #18 on: May 03, 2016, 09:40:45 am »
I also use those things for LED strips or charging large batteries (after mods - current limiting, ouptut voltage) but never used them for critical loads.

These days, I look at the local e-waste junk yard and scrounge server PSUs and get them the same or cheaper but definitely better designed and more reliable and nearly always have active PFC. I just picked up a 12.2V 244amp PSU for little change. I don't have time to play with it yet, just need to figure out the control pins to wake it up and attach some input/output leads.
 

Offline Cartel

  • Newbie
  • Posts: 2
  • Country: ca
Re: Dirty cheap Chinese 12V 30 Amp power supply and its build quality
« Reply #19 on: March 08, 2017, 12:54:14 pm »
Op , Turn on some ShortWave recievers and see what you think about them then .
I use mine on my Icom 735...less birdies than my SEC1223...actually no birdies :-//

I opened mine today to mod the fan speed.
Good thing I did, its been like this for over 1 year of daily use, even running a 300W amp for months.
http://imgur.com/a/xyoYG

The recifier is good for 4A with no heatsink.
360W\120=3AMPS no reason for a heatsink
« Last Edit: March 08, 2017, 05:42:20 pm by Cartel »
 

Offline Red Squirrel

  • Super Contributor
  • ***
  • Posts: 2420
  • Country: ca
Re: Dirty cheap Chinese 12V 30 Amp power supply and its build quality
« Reply #20 on: March 09, 2017, 02:09:57 am »
Rubicong.  :-DD      At that price even if the actual electronics are bad it's almost worth buying just for the case.   

I've been wanting to play with making my own PSUs and other than the math, the actual concept seems simple enough, what makes these bad vs more expensive ones, is it simply that they use bad/under rated components or is there more to it? 
 

Offline AF6LJ

  • Supporter
  • ****
  • Posts: 2903
  • Country: us
Re: Dirty cheap Chinese 12V 30 Amp power supply and its build quality
« Reply #21 on: March 09, 2017, 03:22:47 am »
Those are scary looking inside.
I'll stick with a name brand..... :palm:
Sue AF6LJ
Test Equipment Addict, And Proud Of It.
 

Offline james_s

  • Super Contributor
  • ***
  • Posts: 11142
  • Country: us
Re: Dirty cheap Chinese 12V 30 Amp power supply and its build quality
« Reply #22 on: March 14, 2017, 10:06:23 pm »
Rubicong made me chuckle.

If you want a *good* 12V high current power supply, you can't beat hot swap server PSUs. They're dirt cheap, often times not much more than the cost of shipping. I use a 12V 56A server power supply to run the charger I use with my RC aircraft.
 

Offline Miyuki

  • Frequent Contributor
  • **
  • Posts: 352
  • Country: cz
    • Me on youtube
Re: Dirty cheap Chinese 12V 30 Amp power supply and its build quality
« Reply #23 on: March 20, 2017, 10:29:16 am »
Oh "good" old TL494 with Bipolar transistors
"Nice" to see this ancient design still around  :-DD

Do they have so big stock of this old components or they have old factory to make them ?   ::)

No offence to old stocks I still use passives from 80s stock (bags of cheap everything from closed factory)
« Last Edit: March 20, 2017, 02:31:13 pm by Miyuki »
 

Offline mariush

  • Super Contributor
  • ***
  • Posts: 3937
  • Country: ro
  • .
Re: Dirty cheap Chinese 12V 30 Amp power supply and its build quality
« Reply #24 on: March 20, 2017, 12:48:10 pm »
It's interesting how they used two ferrite rings to create that big inductor.

As for the bridge rectifier , that GBU808L is good for 8A but it's derated to less than 4A without a heatsink. A bit close for my liking, were it to use such a psu for 300w continuously in 110v countries.

 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf