Cheap Chinese 550V/3A power supply mini unboxing - Page 1
Forum section: electronics / testgear

author: samofab
author_rank: Regular Contributor
timestamp: May 16, 2017, 01:50:24 pm
content: Hello,I bought this cheap 550V / 3A power supply from taobao. I always wanted to have a power supply like this because I can wire it directly to 3-phase motor inverter input capacitors and play around with motors and inverters even if I don't have 3-phase power around. But all 600V units on the ebay were selling north of 500 EUR before shipping and import duties.So after triple checking the conversion rates and reshipper costs I decided that cca 200 EUR total is reasonable risk.First impressions:- it didn't blow up on power on- it did blow the fuse on first power up (NTC on input is for sissies)- when was SG3525 PWM controller first introduced?- all caps are 105C rated- only a few things are hand soldered.. for example the nice "floating" snubber network- output has 450V capacitors wired in series- I think I see only 2 FETs on input.. (note to myself: I think they might need a dab of solder)- there's even an input filter- the voltage meter is spot-onWhen I find something to test it with, I'll let you know what happens. I you have any questions or ideas, please ask.Edit: this is SW-1800-550 from taobao seller mindi1981

author: nctnico
author_rank: Super Contributor
timestamp: May 16, 2017, 05:30:02 pm
content: The Pope's doo-doo! The mains input wires are stuck on the board with solder.

author: bktemp
author_rank: Super Contributor
timestamp: May 16, 2017, 06:06:03 pm
content: Yes, it looks poorly designed. 200 EUR seems to be ok for a 1.5kW power supply, but I would have expected a better build quality:Many larger electrolytic capacitors are mounted at an angle.The wires at the mains switch are pretty close to the secondary side without any insulation or protection if they come lose.The CE marking on the mains switch is wrong.The output connectors don't look like being rated for 550V DC.It looks like they used the cheapest components they could find: There are several places where the parts used do not match the footprint on the pcb (for example the yellow capacitor next to the mains input on the pcb or the two green electrolytic capacitors near the mains switch.A cable tie is used as strain-relief for the mains input.Most of the air is probably going over the pcb and not through the heat sink.All of that doesn't induce much confidence.

author: james_s
author_rank: Super Contributor
timestamp: May 17, 2017, 05:51:34 am
content: That's a slightly terrifying piece of gear, looks potentially useful if it doesn't blow up, but I don't much like the construction. Look at how close the output wires are to the metal screws holding the fan grill on, is that earthed?

author: thm_w
author_rank: Super Contributor
timestamp: May 17, 2017, 11:36:05 pm
content: Quote from: blueskull on May 17, 2017, 06:06:04 amYou missed a 0 on the end 2,200uF.

author: Vgkid
author_rank: Super Contributor
timestamp: May 18, 2017, 01:07:08 am
content: Could it be a cloned Jinghai capacitor?@ Blueskull : How prevalent is the component cloning/ copying of Chinese home brand components?