Kungber Bench PS Tear Down Images - As Requested

[DW1961]

Well a few weeks later and I had a cheapo "Wanptek' branded 120V 3A power supply arrive with a powerful inner core  This job is fine with some ripple and noise as it will just be powering a hot wire cutter.



Interesting having a compare it along with yours are either the same or a close cousin mainboard and likely front display board (different orientation). Similar slightly suspect Earthing connections but at a quick first look somewhere close.

I will clear the bench and fire up some proper testing over the next day or two including a look at ripple/noise and loaded and unloaded.

100V? Seriously? Wow. Kinda cool.

I would check with the local FBI to see if carrying around a power supply that has a small nuclear device in it is actually legal. On the upside, you shouldn't even need to ever plug it in. In fact, you cold start your own power company with it.

Kidding a side, how much was that? Looking forward to you scoping it.

Found it on Amazon: https://www.amazon.com/Wanptek-DC-Power-Supply/dp/B08F7HFNK2?th=1

[beanflying]

I will admit I might have 'massaged' their marketing picture a little

I got mine via AilExpress with the Wanptek badge for a bit less than @med6753 got a Kungber branded one via Amazon USA ($90USD) https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/msg3592146/#msg3592146

[TurboTom]

Shame that none of these entry level switchers include a proper PFC, which makes them illegal to be sold in many countries "officially". IMO, this is also a clear indication for their general level of sophistication and quality (or rather lack thereof)... Yet, for many applications these "El Cheapos" are quite useful.

[DW1961]

Shame that none of these entry level switchers include a proper PFC, which makes them illegal to be sold in many countries "officially". IMO, this is also a clear indication for their general level of sophistication and quality (or rather lack thereof)... Yet, for many applications these "El Cheapos" are quite useful.

Why do you say none of them use PFC? Even cheapo computer power supplies have PFC circuits. Even really nice computer power supplies are less than 80 bucks, and incorporate PFC circuits. Corsair makes some really clean PSU and they all have PFC circuits--they'd have to in order to run PCs (although before PSU became really clean, about 2010 or so, we were running computers on those noisy, nasty, dirty early computer PSUs, and having little failures with the equipment--lol). I did have one let go and take out the entire rig, motherboard, drives, RAM everything. But that was back around 1999. And, only one that I knew of among all of my computer building friends).

I was just wondering why you said the PSUs here don't use PFC?

[DW1961]

I will admit I might have 'massaged' their marketing picture a little

I got mine via AilExpress with the Wanptek badge for a bit less than @med6753 got a Kungber branded one via Amazon USA ($90USD) https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/msg3592146/#msg3592146

I'm really interested in your tests. When are you gig to test it?

[DW1961]

Shame that none of these entry level switchers include a proper PFC, which makes them illegal to be sold in many countries "officially". IMO, this is also a clear indication for their general level of sophistication and quality (or rather lack thereof)... Yet, for many applications these "El Cheapos" are quite useful.

I contacted Kungber and asked if they used TC and they said, "No." Isn't that a really cheap circuit to include? If so, why not just add it?

[beanflying]

Shame that none of these entry level switchers include a proper PFC, which makes them illegal to be sold in many countries "officially". IMO, this is also a clear indication for their general level of sophistication and quality (or rather lack thereof)... Yet, for many applications these "El Cheapos" are quite useful.

I contacted Kungber and asked if they used TC and they said, "No." Isn't that a really cheap circuit to include? If so, why not just add it?

https://en.wikipedia.org/wiki/Muntzing 

When you chase the price down to what the Chinese manufacturers think we want at the expense of increased reliability and features then we get what we deserve. In a recent mid life crisis (I have had three now and am working on a 4th) I was importing Kites from Europe, the USA and China. When I raised concerns over samples from China the reply was all to often along the lines of 'it is to make it cheaper' or 'it doesn't matter they are only for beginners'. When you turn around and then ask for a particular spec or tweak and buy sufficient quantity that same flawed design for 20-30% more got brought up to a European or USA made standard and was still way under those costs. The question really needs to be would we as consumers pay that 20-30% more to random company X in China for features?

Re testing for mine I fished out some spare 250 resistors and I will temporarily re task two more out of another box and strap them onto some heatsinks. 6 in parallel for circa 40 across 120V and 3A and for short bursts will handle full power of the supply.

[robert.rozee]

Is the floating voltage on this unit bad or could cause problems?

connect a 1 meg ohm resistor between the negative output (black) terminal and the ground (green) terminal. now measure the voltage across this resistor. calculate the current with I=V/R. report back both the (very small) voltage you measure, as well as the (even smaller) current calculated.

cheers,
rob   :-)

[TurboTom]

Shame that none of these entry level switchers include a proper PFC, which makes them illegal to be sold in many countries "officially". IMO, this is also a clear indication for their general level of sophistication and quality (or rather lack thereof)... Yet, for many applications these "El Cheapos" are quite useful.

I contacted Kungber and asked if they used TC and they said, "No." Isn't that a really cheap circuit to include? If so, why not just add it?

An active PFC adds at least one more HV power semiconductor, a fast power rectifier (with asscociated heat sinking provisions for those two components), a power inductor, a controller IC and miscellaneous passives to the BOM. Since the gadget will work perfectly well without that complication, albeit with a much higher crest factor and thus feeding considerable current noise/harmonics back into the mains, the disadvantages of the missing PFC don't get directly obvious to the individual user as long as the the electricity provider can cope with the situation.

But the shift from analog PSUs in all kinds of devices to switch-mode technology during the past three decades exacerbated the situation up to a point that all of the components of the electricity supply chain had been pushed to the limit. Thus the legislation nowadays requires (new) electrical appliances above a certain power consumption to have to be equipped with a PFC to be legal in most countries. And that's why (practically) all of today's PC and laptop power supplies are equipped with such a circuitry. But especially the low-end, "hobby-grade" switch mode power supply manufactures do without this complication - see the "Muntzing" approach mentioned by @beanflying.

[DW1961]

Shame that none of these entry level switchers include a proper PFC, which makes them illegal to be sold in many countries "officially". IMO, this is also a clear indication for their general level of sophistication and quality (or rather lack thereof)... Yet, for many applications these "El Cheapos" are quite useful.

I contacted Kungber and asked if they used TC and they said, "No." Isn't that a really cheap circuit to include? If so, why not just add it?

An active PFC adds at least one more HV power semiconductor, a fast power rectifier (with asscociated heat sinking provisions for those two components), a power inductor, a controller IC and miscellaneous passives to the BOM. Since the gadget will work perfectly well without that complication, albeit with a much higher crest factor and thus feeding considerable current noise/harmonics back into the mains, the disadvantages of the missing PFC don't get directly obvious to the individual user as long as the the electricity provider can cope with the situation.

But the shift from analog PSUs in all kinds of devices to switch-mode technology during the past three decades exacerbated the situation up to a point that all of the components of the electricity supply chain had been pushed to the limit. Thus the legislation nowadays requires (new) electrical appliances above a certain power consumption to have to be equipped with a PFC to be legal in most countries. And that's why (practically) all of today's PC and laptop power supplies are equipped with such a circuitry. But especially the low-end, "hobby-grade" switch mode power supply manufactures do without this complication - see the "Muntzing" approach mentioned by @beanflying.

Very interesting, Tom. Thanks for that information.

[Tekjive]

So I just bought this unit, worked great and stable and accurate the last week, goto use it today, recall mem1 @ 12v/2a, play some, goto turn off active power (rubber on/off button) and it doesn’t respond, I press it a few times and nothing, I power down, unplug and replying and power up and still the buttons will not respond. I open it up to take a look and see there’s 2 wires clipped from the larger front panel harness and soldered to the main ground, which is not done in the pics on the 1st post. Any idea why this is done or why the front panel has stopped responding? Any help would be great, ty.

https://imgur.com/a/aYlOO4X

It’s actually the Main Earth GRD and V- lines from the panel, seems the main chip on the daughter front board, TM1640, must have gone bad ...out of nowhere ...joy.

https://imgur.com/a/BThXhtA

That’s just the LED Drive control circuit ...lol, updating post as I find info ...just at a loss :/

Well, after completely disassembling the front, checking all solder connection, reattaching the Main GRD and V- to harness, and giving it a good thump for a good measure ...lol, it’s working again. I’m assuming something is loose somewhere in the front panel, if it happens again I’ll reflow everything, if anyone knows what IC controls the front buttons I’d appreciate the look out. 

[DW1961]

So I just bought this unit, worked great and stable and accurate the last week, goto use it today, recall mem1 @ 12v/2a, play some, goto turn off active power (rubber on/off button) and it doesn’t respond, I press it a few times and nothing, I power down, unplug and replying and power up and still the buttons will not respond. I open it up to take a look and see there’s 2 wires clipped from the larger front panel harness and soldered to the main ground, which is not done in the pics on the 1st post. Any idea why this is done or why the front panel has stopped responding? Any help would be great, ty.

https://imgur.com/a/aYlOO4X

It’s actually the Main Earth GRD and V- lines from the panel, seems the main chip on the daughter front board, TM1640, must have gone bad ...out of nowhere ...joy.

https://imgur.com/a/BThXhtA

That’s just the LED Drive control circuit ...lol, updating post as I find info ...just at a loss :/

Well, after completely disassembling the front, checking all solder connection, reattaching the Main GRD and V- to harness, and giving it a good thump for a good measure ...lol, it’s working again. I’m assuming something is loose somewhere in the front panel, if it happens again I’ll reflow everything, if anyone knows what IC controls the front buttons I’d appreciate the look out.

I'd just return it! Some units are going to be lemons.