EEVblog #315 - Korad KA3005P Review/FAIL

[Jetiman]

How can I see if this is the new version or not?
Will buy me this.

http://www.pollin.de/shop/dt/ODE0ODQ2OTk-/Stromversorgung/Netzgeraete/Regelbare_Netzgeraete/Programmierbares_Netzgeraet_mit_USB_Interface_KORAD_KA3005P_30_V_5_A.html

[PeterFW]

How can I see if this is the new version or not?
Will buy me this.

Mail them and ask or just order it.
If you do not like it, send it back.

That costs nothing besides the hassle to carry that thing back to the post office.

From the picture it seems to be a old unit, but maybe it is not up to date... it is pollin after all.

[Jetiman]

Have it ordered, but I can see whether new or not?

Comes in 2 days (Germany holiday tomorrow)

[ProBang2]

How can I see if this is the new version or not?
Will buy me this.

http://www.pollin.de/shop/dt/ODE0ODQ2OTk-/Stromversorgung/Netzgeraete/Regelbare_Netzgeraete/Programmierbares_Netzgeraet_mit_USB_Interface_KORAD_KA3005P_30_V_5_A.html

Define "old" and "new" version.
If the "old" version means the device that failed in Dave´s test and the "new" version is the device with the changed board (3 big elcos), then is this the "new" version.
Sure?
Sure. Very sure.

You can open it and check yourself without any problem. There is no "warranty void" sticker.

[Jetiman]

How can I see if this is the new version or not?
Will buy me this.

http://www.pollin.de/shop/dt/ODE0ODQ2OTk-/Stromversorgung/Netzgeraete/Regelbare_Netzgeraete/Programmierbares_Netzgeraet_mit_USB_Interface_KORAD_KA3005P_30_V_5_A.html

Define "old" and "new" version.
If the "old" version means the device that failed in Dave´s test and the "new" version is the device with the changed board (3 big elcos), then is this the "new" version.
Sure?
Sure. Very sure.

You can open it and check yourself without any problem. There is no "warranty void" sticker.

Left = New
Right = old

Correct?

[ProBang2]

Correct! 

[ProBang2]

Since i use linear "old" fashioned psu's, like Kepco, Hp/Agilent,  I  never had any problems after that.

The best switched modes psu's i've tested, where from Xantrex.   Oh! man  many times i have tried to kill them, pushed them to their limits.   Rock solid in every aspect, but $$$.

BTW: Just found this in another thread:

Who can't use another power supply?   This was an impulse buy 800W Xantrex XTR33-25.  Clean and fully operational for $75 shipped.   There are no better power supplies  than XANTREX made by real Canadians.

Funny, one of my recent purchases is a Xantrex power supply and it oscillates like a guitar string    It's really too bad, I bought for the GPIB capability and had really looked forward to having a computer controllable power supply.

Shit happens...   Everywhere.

[Jetiman]

Pollin

New or old?
Looks like mix of

------------------------

[ProBang2]

Middle.

This is the first version after the failing issue.
(On the power-transistor-board one big cap, but different designed pcb. Compare the placement
of the connectors in this video: https://youtu.be/_HrvuHSywms?t=1m16s.)
After this version they had changed to three caps instead of one big cap. Perhaps that is cheaper...

From where Pollin got this quite old version?

I don´t know, really...   

(I bought my KA3005P, roughly one year ago, from Pollin too. I got the newer version with three caps.)

[Jetiman]

hmmm 

So my is Middle old and new?

So return and new order? Or keep?

[ProBang2]

There is no real reason. It is nothing inherent wrong with your version.
The behavior, technical data and UI are not different at all.
But I can understand your wish, to get the newer version.

[MSM]

From where Pollin got this quite old version?

I don´t know, really...   

(I bought my KA3005P, roughly one year ago, from Pollin too. I got the newer version with three caps.)

Something really fishy is going on here! I asked Pollin about the production date of these PSUs. They said they don't know!! Also, they've listed the KA3005P for 88+4.95€ on ebay and their own website, but 156.25€ on Amazon.de!!

[Barny]

Pollin is knewn as "Resteverwerter" (remnants seller).
They buy their parts from closing shops / companies, overproduction, stock-clearance,....

I'ts no good idea to buy parts with "expire date" like bateries, elcos,... at Pollin.
Its

And that shops sell their parts at n higher price at Amazon should be well knewn.
(Amazon-fees,...)

[Jetiman]

Do I understand correctly, version is not the latest, but it does not have the errors of version 1?
Then I could keep the So?

[ProBang2]

Correct.

[snovotill]

The original part numbers and identifying marks have been obliterated from the tops of the two microprocessors on the internal circuit boards. That is because THIS power supply hides a very special secret. The main MCU is actually a Nuvoton/Tang M054LAN or M054LDN part which contains a 32-bit Arm Cortex-M0 core. It is clocked by a 12MHz crystal but has an internal 4x muliplier so it actually runs at a very fast 48MHz. Why you ask? Because THIS power supply performs voltage and current regulation in software via DSP techniques. This is the reason why there are so few analog components and circuit boards inside THIS power supply as compared to any other. The second CPU, located on the USB/RS232 communication board of "-P" suffixed units only, is a Nuvoton/Tang NUC120LD1BN part and it is responsible for handling USB communications with your PC via firmware emulation. These power supplies have been on the market for several years now and it is claimed by various sources that the circuitry and firmware has gone through 3 very beneficial revisions and that the power supplies can now be considered to be fairly finely-tuned and stable machines. After reading several reviews in English, Polish and Chinese to confirm this (thank you Google Translate!), I eliminated all other competitors in this price-range and purchased one of these KA3005P's on AliExpress today, for less than I'd pay on TaoBao+DHL =) It is my hope that the hardware watchdog in the main MCU is correctly configured by the current rev 1.3 or higher firmware, and that the elegant simplicity achieved by eliminating unnecessary analog circuitry through the use of Digital Signal Processing techniques will provide both reliability and performance. Those of you who wish to check the firmware revision of your power supply via USB or Serial port can simply set 9600,8,N,1 and issue the following command without any EOL or CR characters, then see an instant ASCII response: *IDN?

[Svuppe]

Because THIS power supply performs voltage and current regulation in software via DSP techniques. This is the reason why there are so few analog components and circuit boards inside THIS power supply as compared to any other.

Sorry, but I don't believe that is correct.
The processor controls two D/A converters (made by R2R ladders). One for voltage and one for current limiter. These two are set ONLY when changing the settings from the front panel. The rest happens in the analog circuitry (consisting of 6 opamps and a handful of passives).
The overvoltage protection is most likely a software thing, but the the processor is not involved in the regulation loop during normal operation.

[cowana]

Completely agree with Svuppe.

You only have to trace out the schematic to see this is not the case - there are three dual TL082 opamps (U5, U6, U7) which run the control loops for CV, CC and switching between the two.

Not only does it seem unlikely the DSP is running the control loops - but that isn't physically possible, regardless of what software is running! Are you possibly talking about a different bench PSU?

[Lockon Stratos]

Greetings.

I just have a quick question, with the fix Dave presented in the followup video is it safe to buy this thing? (A little bit of noise or overshoot wont matter in my case, it wont power anything "sensitive".) And what is the difference between the KA3005D and KA3005P?

Thanks in advance for the help .

[Andreas]

Hello,

I have 2 KA3005P (with USB/RS232) and 2 KA3005D (without PC interface).
Most time I use them in the 0.5-2A range.
Large overshoot is only possible if you switch off/on the mains AC very fast.
(otherwise the output is switched off on power on).
Normal overshoot is around 0.4-0.5V with light loading.

Largest issue are the loud fans.
One of them I will have to replace in near future.
(has already large vibrations on start up).

With best regards

Andreas

[Lockon Stratos]

Hello,

I have 2 KA3005P (with USB/RS232) and 2 KA3005D (without PC interface).
Most time I use them in the 0.5-2A range.
Large overshoot is only possible if you switch off/on the mains AC very fast.
(otherwise the output is switched off on power on).
Normal overshoot is around 0.4-0.5V with light loading.

Largest issue are the loud fans.
One of them I will have to replace in near future.
(has already large vibrations on start up).

With best regards

Andreas

Thanks . That much overshoot wont pose much problem in my use-case. (And i think i will buy the one with the USB interface.)

[marcone]

Opened my KA3005D today to troubleshoot missing output voltage when outut is enabled, connector going to the output terminals had become loose. Too bad they did not glue down all connectors because otherwise construction seems very tidy for a 60 Euro power supply.
Mine is the latest revision with the recessed binding posts; snapped a picture of the control board, there is actually a finned heatsink fitted. Power transistors are 2x 2SD1047 and gone are the fake Nichicons. Think I'm going to but the 10A version as well at some point, should make up for a good battery charger.

[almamater]

Hello everyone, i bought my Korad KA3005D, received it yesterday.

This is the Old version ?









I think it's the Old (due the the one Big Cap and the connectors layout).. i bought from  reichelt online store. If its old, what should i do?!

[Andreas]

Hello,

They seem to change the boards on every delivery lot.
At least your supply has a reasonable heat sink against the thin plate with bent fingers.

Afaik the new design is made with MJL 3281A transistors.

with best regards

Andreas

[LastManStanding]

Hi Almamater.
You have the latest version - here they have omitted the terminals on the front. No way to attach wires, very annoying...
My device also has no terminals. I've not noticed that at the sellers website, so i'm thinking it over to hold this device or send it back.
Additional to that the fan rattles at idle.