Caution when Buying Cheap Power Supplies from China (AliExpress, Ebay, Banggood,etc.)
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- čas přidán 14. 01. 2022
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In this Video I just want to remind what it can mean to buy Cheap PSU's from China.
It is absolutely OK and the PSU's are mostly OK, as long as you are aware what you can expect when paying just few bucks for a PSU that would cost normally several times the paid Price : Match your Expectations to what you Pay!
Corners will be cut in any possible way to minimize Production costs, this is Normal, expected and acceptable as long it not gets Dangerous!
As an example I use a currently purchased a HJS-480-0-300 480W 300V 1.6A Output Half Bridge Closed Frame SMPS from AliExpress that is even Better Build that Other ones !
This PSU has no PFC !
In Short, be aware that Input and Output Capacitors can be "Repurposed", Damaged during the Extraction from old Scrap PCB'S or even Fake !
In my case we have Damaged "Repurposed" Electrolytic caps in a 300V 1.6A Output !
AliExpress High Voltage Power Supply short follow-up Video: • AliExpress High Voltag...
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!!! Thank you to all my Current and new subscribers !!!
#electronicscreators
#highvoltage - Věda a technologie
If you guys buy power supplies like this and they have a 110/220 switch, remove it and wire it directly with jumpers as to your voltage mains. These switches over time corrode and lead to failure. Just remove them. I ALWAYS check solder connections as first thing, then I check the build quality then I check function and operation. I just saw that IC in a socket. If you are skilled enough remove that socket they cause problems too.
Thank you, Thank you!!!! ... for explaining this from an engineering perspective. I learned my lesson years ago when I knew absolutely nothing about power supplies. The one I purchased (brand new out of the box) DID catch fire while only pulling 30% of the rated power... That was my "never again" moment. I see you mention Astec (now Emerson) in a reply below. That is one of my favorites, especially the MVP series. Thank you again, seriously, you may have just saved someones life...
BTW: here in the states, a psu like the one you review here in this video, would have NEVER been allowed to reach our shores. I don't know why the regulations have changed.
Hello, Thankyou, I use these kind of Cheapos for HV Tesla coils testing, nothing critical and always check them optically and electrically when I received them. This one was particularly dangerous with the bad cap bcs it at at the 300V Output, was a Fire hazard waited to happen.
For critical or work applications i use Meanwell, Astec, Delta, etc. depends on Budget and requirements.
I bought one of these and it looked like an child soldered it, so horrible. For what i know an child could have probably even assembled the power supply, i threw it out like it was the plague and kept the fan and casing
I wonder how weel the isolation in the transformer is done.
I seen this with Chinese power supplies myself with re-branded salvaged capacitors, The bulk caps were an absolute disaster covered with a Dongbaohe label, the caps had less than 500uf for a 33,3 Amp rated supply and more than 2ohm ESR, not only that but pretty much all parts were salvaged and dented or crooked and you should see the solder job they made, oh boy it was a sight for sore eyes, not only that many connections were lose or cold soldered it was also full will solder balls and flux all over the board almost shorting out the mains over to the output side. so indeed be careful and watch out for dodgy Chinesium products when trying to get a good bang for the buck
I used (for non Prof) quite a lot of these cheapies, all in a condition : "OK, they work" nothing more, but this one with an Output Voltage upto 300V at upto 1.6A was eye opening.... I have no Problems reusing Parts so at least I know they are not fake(I do that myself to when I need stuff fast) but putting mechanically damaged parts in a High Voltage Output PSU ist S**T.
@@KonstantinGrigoriadis indeed, and I don´t dare to think how the safety isolation is inside the transformer either because those often just have the lacquer on the wire isolating the primary and secondary. But I mean not everything is bad and China makes a lot of good stuff too, but it is a general thing when it comes to cheap stuff they are over rated and will fail at the stated voltage and current. I built my own HV power supply for my Tube audio instead, variable stabilized output up to 500 volts and half an amp with ripple less than 1mv peak to peak which is placed above 20khz. The power is actually so clean you don´t even need any filters in the amp. I put a lot of effort into that and built everything myself including designing and making the circuitry with oscillators, drivers OV-protection automatic idle and everything even re-winding a toroid for it. it is a soft switching push-pull design with fet-dampers working at about 22khz or so, I can adjust every aspect of the oscillator, and if the feedback fails the driver board also have an adjustable over voltage protection that shut down the psu in case the voltage rise too much and it stays that way until you manually cycle the main power. My goal was perfect regulated DC but if you would drop that PSU on your foot you never gonna walk again
@@KonstantinGrigoriadis I also think the smaller trannies are usually more unsafe in the Chinese stuff.
for my build I was lucky enough to get my hands on a free huge toroid transformer like 5-700VA it was potted in epoxy resin but I carefully removed it and all of the secondary winding and then winded my own on the primary winding and use the transformer inverted, I have a 400watt Meanwell main supply that powers all components in the supply including the two huge bulk caps which is 39000uf each that powers the primary side in the high voltage converter, The output is very tightly regulated and tested up to 700volts but is then limited to 500volts as this is the maximum for the caps I use and for the desired margin for regulating the voltage, I have then a 2-stage filter that first goes through a rectifier into a pair of Rubycon 500V 12000h rated caps and then fed into a massive 17mh choke, the choke then goes into the most expensive component in my whole build the absolute abysmal Kemet 13000uf 500V capacitor, that thing is like a pack of milk in size, it is rated 35amps in ripple current at 10khz, it filters the remaining noise from the output voltage, the regulator I built is adjustable from about 200V to 500 stepless and it will keep that voltage exact no matter how the load is on the output, no noise no nothing, you can even take that output and feed into the grid of a preamp directly and you won´t hear a thing.
I have output voltage gauge and also current gauge and also indicators for the status, including: Ready, Idle, Run, and OV Protect, All made with a single LM258 (same chip also monitor, trips and hold the OV protect as well, mind blown🤯) it was a hard nut to crack making all that with a single opamp, took many beers. Main power voltage gauge for the main power, also switch for running mode: always on, Off, or auto (external start)
I have a built an audio detector that automatically detect audio and it also activates the external power supply when audio is playing, when nothing is playing this audio detector not only put the power supply into an idle state it also mutes the speakers completely, when the external voltage is off/idle my amp runs at lower power with it´s built in power transformer which saves the tubes when nothing plays or I just don´t care to have the best sound.
But this supply is only made to supply absolute perfect DC high voltage into the amplifier and also bypass the filter stages, this way I get nothing in the way for the tubes to give best possible power and audio quality when the external supply power the amp, it needs no additional filters in the amp, but I always build it with resistor dividers for screen grids and pre-amp tubes so I don´t need any extra voltage sources that way, the whole amp just follows the increased voltage all together, and I have this specific amp cathode biased with 3 different levels, it plays any 6V6,6L6,EL34,6CA7,807, I typically use EL34/6CA7 with it in True triode mode, it is a single ended dual mono amp.
i can also use any ECC83 or 85 pin compatible pre-amp tube with a selection switch, it just plays anything i plug in.
when I designed this amp I aimed for wide compatibility and options, it also plays in pentode mode, have tone control and negative feedback selectable. plus various anode impedance settings. and more.
but the filaments are always powered with the transformers i have in the amp itself, it also have 2 trannies, one for the filaments in the output tubes and for the built in high voltage, and a separate for powering the pre-amp tube filaments with regulated DC along with indicator lights and hour tachometer. in short all components I built is working together as one but even on their own if needed, if the external supply won´t work one day I can just happily play on with the built in power of my amp. but it is the mix of them that makes the best of them.
I have made my own pre-amp for this as well, Tube VU meter, and additional Push-Pull tube amp sub amplifier and modified speakers for them.
years of work put into making that stuff all together, But I love them, it is pretty special when you make something yourself and you can sit down and listen to your own work :)
@@Pulverrostmannen
Stunningly the Ouput Transformer is OK to Good rated, thick lacker on the Sec Winding, double tape Insulation between Pri and Sec, double between layers. The insulation covers completely the Primary almost to the Leads where its soldered on the Pins. These bigger Transformers where all ok (at least the ones i opened) in contrary to many of the small wallwart style psu Transformers that where 90%+ Dangerous.
I made some designs for a Complete Tube PSU, meaning Anode V upto 800V 70W Total, plus ADJ Screen V upto 450V and ADJ Grid V upto -200V, all Flyback Based planned to be in on enclosure with an addition 0-30V 20A Fillament DC Suppy.
At the end it came much more expensive than using ready made stuff and just tweaking them to fit my needs. The costliest part where the Transformers, that even made in china from Large Manufacturer to my Specs, still are expensive and winding mycelf was not an option :-) The 800V 70W (70kHz) PSU is fully Digital with a 3.2" TFT but never came out of the Prototype :-) was planned as a DC/DC Flyback Boost to can be operated in a car too without Inverter. that was 4 Years ago :-)
Your design sounds Interesting, did you wind your Own Transformer ?, One Output HV Winding or more Lower HV Output Windings Stacked ?, Doubler Output ?
@@KonstantinGrigoriadis I built my transformer by removing the old secondary winding completely and winded my own with two heavy gauge 12 turns each Center tapped around the toroid core making the transformer become about a 1:60 ratio. I drive the transformer inverted meaning the primary winding becomes the secondary instead. I feed the new winding with my high current oscillator with about 12-13 volts and get high voltage out the other winding. This makes it much easier to make it work since you don’t need to wind hundreds of turns for it to increase the voltage.
I done it this way a lot with toroid transformers as you would never want to manually wind so many turns it needs otherwise. But a few turns is fine to just invert the input to be the output instead. But there is a limit how much voltage you can reliably use too as the primary won’t be rated for an infinite voltage. Taking the rms peak voltage plus some margin I never would go more than 500VDC on a 240VAC rated transformer inverted but I test them with at least 700volts on the output.
And finding big nice 400volt toroids is not an easy task either but it is preferred for higher voltages than 500Volts
They're usually decent enough, but I've purchased some with components that are completely unsoldered. One had one of the main torroidal transformers, not soldered what-so-ever, rolling around inside the metal case when it arrived. I finished the solder job and it worked great. ...but still. No QA/QC of any kind, and who knows what other corners they're cutting.
They are ok for the price Normally, they work, but some of those are Awful due lack of QA/QC, the one with the punched cap was the worst and most dangerous o had till now.
Can I run an electric forklift without batteries and powered by 220 vac 3000watt 80Amp power supply ?
I have similar power supply DC12V 24V 36V 48V 60V 80V 120V 4A Adjustable Charger Digital Display Current Voltage Adjustable Switch Regulated Power Supply. Supply it's working but I need more currents, and I program the same current for amplifier as consumer, and in idle amplifier state current is around 0.7A, when I start amplifier current goes up to 1.1-1.3A, but after some time current just drops around 0.2A, when I'm looking on LCD power supply screen. That would be that cheap chinese high voltage capacitors connected in serial or something else!!!???, amplifier is in good state, checked on other supply
Dear Konstantin. I have a similar brand but the different model (HJS 480 0_160v & 0_3 A) and I have a problem with it. I want a board map to repair it but I couldn't find any board map for my model. Can you please provide an image from the board of this model that you have?
Hello, Please contact me via Email to send you the Schematic, my Email is in my Channel Description.
Cheers,
Konstantin
Can you please share again I just bought 1 from eBay.the power supply had only voltage adjustment I want to see if could do the current adjustment.from my first glance mine 0-60vdc look close to the one you have the only difference is no second variable resistance and no location in PCB board.
Hello, Please contact me via Email to send you the Schematic, my Email is in my Channel Description.
Cheers,
Konstantin
Disgusing. That's why I don't buy these from China. These is also the possibility of the cheap PSU failing and damagimg whatever is being supplied by it. I always choose Meanwell or other reputable brands.
At least. it didn't take life, unlike products from Boeing or Airbus!
Nippon is very high quality capasitor long life
Legend
Greeting
I would buy such a power supply 12V-40A
Is it suitable for daily use in electrolysis?
Thank you
Hello, well its a PSU made to cost a minimum. I have a similar one working for 2 Years now without issues, but anither failed in one Month (I repaired it though andworks since then) so its a little a gamble what y will get. Cheers, Konstantin
@@KonstantinGrigoriadis Can you recommend a seller on any page...
Hello, not really bcs I donno what you will receive.. I would suggest to goto aliexpress and search for 12V 40A , you will find many and choose the one with the best reputation and highest sells.
A 300V dc psu? Why does anyone need that?
Hi, for Vacuum Tube designs
You would be surprised. It's just not mainstream...mostly specialized use. Many things I work on use 300vdc power. It would be great to have a power supply to test and TS those components off of the unit, and inside on a workbench, unfettered by the weather and such. This might not be useful for everyone, but I'm relieved to finally start finding channels that work with this voltage level.