Author Topic: EEVblog #315 - Korad KA3005P Review/FAIL  (Read 217083 times)

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Offline GoneTomorrow

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Re: EEVblog #315 - Korad KA3005P Review/FAIL
« Reply #325 on: September 01, 2017, 02:06:43 am »
Additional to that the fan rattles at idle.

Put a 50uF electro capacitor across the fan, it's caused by a really coarse PWM. Smoothing with a cap stops the rattling.
 
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Offline jameson

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Re: EEVblog #315 - Korad KA3005P Review/FAIL
« Reply #326 on: November 05, 2017, 04:16:28 pm »
Hello! I have the same version of Korad as described by Almamater. Voltage when output is off is 10 mV. The minimum value that was obtained after calibrating is 2 mV. Is it normal? What is the voltage when ouput is off on your power supplies?
 

Online Andreas

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Re: EEVblog #315 - Korad KA3005P Review/FAIL
« Reply #327 on: November 05, 2017, 04:46:05 pm »
Hello,

what do you expect?
Each power transistor has leakage currents in the order of some 100uA or even mA.
A 30V/5A power supply is neither intended for 2mA LEDs nor 1.5 V logic supplies.
Would be the same if you use a 20 pound sledge hammer for a drawing pin.

Here "output off" means  4.7 mV or 12.9 mA leakage current.
Zero voltage, output on = 9.5 mV or 26 mA

Accuracy spec is 0.5% (of 30V)  + 20 mV which means up to 170 mV total error.
similarly current 0.5% (of 5A) + 10 mA which means up to 35mA current error.
So your device is well within spec.

With best regards

Andreas

 
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Offline jameson

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Re: EEVblog #315 - Korad KA3005P Review/FAIL
« Reply #328 on: November 05, 2017, 06:41:35 pm »
About the one I thought, but expect that the leakage current will be less. I have not found out what it is transistors are in my Korad.
In any case thank you for a comprehensive reply.
 

Offline Decoman

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Re: EEVblog #315 - Korad KA3005P Review/FAIL
« Reply #329 on: November 28, 2017, 05:18:06 pm »
Did anyone ever figure out how to use the over volt and over current protection feature, and how it works?
 

Offline janoc

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Re: EEVblog #315 - Korad KA3005P Review/FAIL
« Reply #330 on: November 28, 2017, 07:23:33 pm »
Did anyone ever figure out how to use the over volt and over current protection feature, and how it works?

I believe the original Dave's review video shows both. The OCP protection will shut the output off when you exceed a preset current instead of going into constant current mode.

The OVP protection will do the same if the output voltage exceeds the preset limit. Now this I didn't play with, not sure whether it protects against user's stupidity (sending 12V into a 3.3V circuit) or whether it can handle overvoltage at the output from an external source too.
 

Offline Decoman

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Re: EEVblog #315 - Korad KA3005P Review/FAIL
« Reply #331 on: November 28, 2017, 07:49:10 pm »
My impression from the video was that he did not know how to actually set the over volt and over current protection value.

Does anyone know? I'd like to know as I might perhaps want to use this unit.
 

Offline janoc

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Re: EEVblog #315 - Korad KA3005P Review/FAIL
« Reply #332 on: November 28, 2017, 07:56:07 pm »
My impression from the video was that he did not know how to actually set the over volt and over current protection value.

Does anyone know? I'd like to know as I might perhaps want to use this unit.

On mine you set the max current as normal and then you press the OCP button. Now when you short the output the supply will turn off the output with a beep instead of going into a constant current mode.

The OVP mode is not settable from what I can see - it likely only protects against external overvoltage on the output when you turn it on.
 

Offline Decoman

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Re: EEVblog #315 - Korad KA3005P Review/FAIL
« Reply #333 on: November 28, 2017, 08:03:15 pm »
In that case, I would think that one would want to have OVP (over volt protection) feature enabled, always, which seems a little odd to me, knowing very little about electronics.

I can't help but wonder that the feature for the OVP would seem odd in that respect.
 

Offline janoc

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Re: EEVblog #315 - Korad KA3005P Review/FAIL
« Reply #334 on: November 29, 2017, 10:30:43 am »
In that case, I would think that one would want to have OVP (over volt protection) feature enabled, always, which seems a little odd to me, knowing very little about electronics.

I can't help but wonder that the feature for the OVP would seem odd in that respect.

The OVP protection (if it does what I think it does) only really protects the power supply by disconnecting it from the load should it detect an overvoltage condition. Which is not a very common situation - how often do you have two supplies powering the same power rail? And in such case your DUT would get fried regardless of OVP being on or off in such case because it would keep getting powered from the other supply.

The other theoretical situation is that it could kick in should the voltage regulation in the supply fail (like in the original Dave's video) - however, in that case all bets are off and it is very likely that the protection circuitry itself would get fried as well.

Having this constantly on would be likely annoying, especially if you are working with inductive loads that could kick up some voltage spikes on the power rails - it would keep triggering the protection and shutting the supply off.

I have personally not found any use for the OVP mode. The overcurrent protection is much more useful, even though I am mostly keeping the supply in the default configuration where it goes into a constant current mode - you don't have to constantly reset the supply after even in a brief short circuit or overload.
« Last Edit: November 29, 2017, 10:32:46 am by janoc »
 

Offline glarsson

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Re: EEVblog #315 - Korad KA3005P Review/FAIL
« Reply #335 on: November 29, 2017, 10:58:20 am »
Which is not a very common situation - how often do you have two supplies powering the same power rail?
When you use the lab PSU to charge a battery. Turning off the PSU in this setup is destructive to many PSU output stages.
 

Offline janoc

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Re: EEVblog #315 - Korad KA3005P Review/FAIL
« Reply #336 on: November 29, 2017, 11:09:41 am »
Which is not a very common situation - how often do you have two supplies powering the same power rail?
When you use the lab PSU to charge a battery. Turning off the PSU in this setup is destructive to many PSU output stages.

In that case an overvoltage protection won't help - the battery voltage is never going to be higher than the voltage at the output cap of the supply. So if you turn the output off and want to turn it back on, it will not get triggered (the output voltage of the PSU is higher than the battery voltage).

If you mean turning the supply completely off with a battery connected - then the OVP system is obviously useless as it has no power. Also we are talking about a lab supply, something that is designed to handle all sorts of abuse, so I would expect it to have some protection diodes in to prevent this sort of situation.
 

Offline Decoman

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Re: EEVblog #315 - Korad KA3005P Review/FAIL
« Reply #337 on: November 29, 2017, 09:41:59 pm »
Having read Andreas' post above regarding specced output errors, and not knowing much about electronics, I want to ask:

Would this powersupply be ok for powering one or more LED's, which run with 2-3V and 10, 15 or 20 mA? Or would this powersupply be too crude?

Looking at youtube videos I think I've learned that LED's don't like voltage overshoots. As the LED's will easily burn out, when being over powered.

Also, the unit is specced for 110-220V, but would it be ok, or a bad idea to have it run on 230V? (Norway). My impression is that this power supply can run 220V and the specced + 10% would cover 230V, but if there might be issues, I have no idea myself.
« Last Edit: November 29, 2017, 09:46:10 pm by Decoman »
 

Offline janoc

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Re: EEVblog #315 - Korad KA3005P Review/FAIL
« Reply #338 on: November 30, 2017, 04:59:14 pm »
Having read Andreas' post above regarding specced output errors, and not knowing much about electronics, I want to ask:

Would this powersupply be ok for powering one or more LED's, which run with 2-3V and 10, 15 or 20 mA? Or would this powersupply be too crude?

Looking at youtube videos I think I've learned that LED's don't like voltage overshoots. As the LED's will easily burn out, when being over powered.

Also, the unit is specced for 110-220V, but would it be ok, or a bad idea to have it run on 230V? (Norway). My impression is that this power supply can run 220V and the specced + 10% would cover 230V, but if there might be issues, I have no idea myself.

You can power LEDs from it in constant current mode (set the current limit to e.g. 10mA) but do not turn the supply and off with the LED connected. Otherwise you are risking that the diode dies before the output voltage stabilizes if there is any overshoot. It is a decent supply for the price but certainly no high end, so some overshoots and what not are to be expected. Better safe than sorry.

Re 230V - that should be safe, the 220V mains voltage comes with +10%/-6% tolerance, so anything meant to be used with it has to be able to deal with at least 242V. So no worries there.
 

Online Andreas

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Re: EEVblog #315 - Korad KA3005P Review/FAIL
« Reply #339 on: December 01, 2017, 09:42:12 am »
Hello,

10-20mA LED?
I wouldn do that without a series resistor for the LED (on any power supply which can deliver more than 50 mA).
Especially as the KORAD has a 330uF output capacitor.

What happens if you connect a 100R resistor (instead of the LED) to the output when the voltage is set to 15V and current limit is set to 20mA can be seen in the screen shots. (voltage measured across the 100R resistor).

Peak current reaches nearly 150 mA and current declines with a time constant (30ms) corresponding to the 330uF capacitor.
So if you dont care your LED (50mA max peak) may be destroyed here.
Steady state current is 22.8mA (measured with DMM). But this may vary dependent on device and room temperature.

It will be better if you use the off/on button on the KA3005.
(The cheaper KD3005 devices dont have it).
On my device I have seen no overshoot  in this setting.

with best regards

Andreas


Andreas
 

Offline janoc

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Re: EEVblog #315 - Korad KA3005P Review/FAIL
« Reply #340 on: December 01, 2017, 10:24:50 pm »
Hello,

10-20mA LED?
I wouldn do that without a series resistor for the LED (on any power supply which can deliver more than 50 mA).
Especially as the KORAD has a 330uF output capacitor.

What happens if you connect a 100R resistor (instead of the LED) to the output when the voltage is set to 15V and current limit is set to 20mA can be seen in the screen shots. (voltage measured across the 100R resistor).

Peak current reaches nearly 150 mA and current declines with a time constant (30ms) corresponding to the 330uF capacitor.
So if you dont care your LED (50mA max peak) may be destroyed here.
Steady state current is 22.8mA (measured with DMM). But this may vary dependent on device and room temperature.

It will be better if you use the off/on button on the KA3005.
(The cheaper KD3005 devices dont have it).
On my device I have seen no overshoot  in this setting.

with best regards

Andreas


Andreas

I have obviously meant using the output on/off button on the Korad or disconnecting the leads, not toggling the main power switch. That would be a terrible idea, indeed - both because of the capacitor charging currents and the potential transients when turning the supply on and off.

Are there variants that don't have this button? I have only seen variants that don't have the 5th preset LED (that you get to by selecting 4th preset and then turning the knob) and have some other function instead of it.

 

Offline Decoman

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Re: EEVblog #315 - Korad KA3005P Review/FAIL
« Reply #341 on: December 10, 2017, 07:38:52 pm »
I ordered the KA3005D variant (without usb), and I thought some might find it interesting if I opened it up (without killing myself ofc) and shares some photos of its innards. I am anxious to learn if there might be any loose items inside. :)
The one I ordered seems to maybe have the four memory buttons, and hopefully this is a newer variant. The unit I ordered should arrive within a week I would think.

I will definitely feel more comfortable knowing what the insides looks like on this unit of mine, before using it, presumably I am receiving a fairly newly manufactured unit. I ordered mine from sra-stores on ebay, if it is any good, I don't know yet. Ofc, I am not qualified to judge, but I suppose there are some basic things i can check.
 

Offline Mr. Scram

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Re: EEVblog #315 - Korad KA3005P Review/FAIL
« Reply #342 on: December 11, 2017, 01:09:41 am »
I opened up my dual rail variant and was surprised to find one massive transformer, instead of the two discrete units tied together I expected. It makes sense to do it this way, obviously, but I understood the units to be constructed differently.
 

Offline Fkossy

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Re: EEVblog #315 - Korad KA3005P Review/FAIL
« Reply #343 on: February 21, 2018, 11:58:09 am »
Hi all,
In my country supply voltage 220V, typically around 210V-230V.
My power supply is meant to work with 220V, but his transformer hums and heats up at even no load.
This is my problem, or typical quality for this power supply?
 

Offline ProBang2

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Re: EEVblog #315 - Korad KA3005P Review/FAIL
« Reply #344 on: February 24, 2018, 02:17:34 am »
Hello.

My KA3005 is declared for 220V mains voltage, too.
Actual mains voltage: 235.2V (measured right now).
When powered on, then there is for less than a
second a strange sound from the transformer. After
that: There is no hum. The sole noise is the air ventilation.
And the unit does not heat up. Even not with a small load.    :-//
It seems, there is a problem with your specific device.
Sorry.
 

Offline chaoticmayhem65

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Re: EEVblog #315 - Korad KA3005P Review/FAIL
« Reply #345 on: April 07, 2018, 06:56:20 pm »
Does anyone have a link to the control software other than v2.6 that is available on the SRA website? Possibly v2.4?
 

Offline HoracioDos

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Re: EEVblog #315 - Korad KA3005P Review/FAIL
« Reply #346 on: April 07, 2018, 07:17:07 pm »
Does anyone have a link to the control software other than v2.6 that is available on the SRA website? Possibly v2.4?
By chance I posted what you might need a few minutes ago.
https://www.eevblog.com/forum/testgear/korad-ka3005p-software-update/
 

Offline chaoticmayhem65

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Re: EEVblog #315 - Korad KA3005P Review/FAIL
« Reply #347 on: April 07, 2018, 10:46:37 pm »
Does anyone have a link to the control software other than v2.6 that is available on the SRA website? Possibly v2.4?
By chance I posted what you might need a few minutes ago.
https://www.eevblog.com/forum/testgear/korad-ka3005p-software-update/

Well thanks for the link, but unfortunately it still has the problems I was having with the other software. The graphs are way too small and the program won't let you maximize the window to full screen. I've tried v2.5 and the window is physically bigger, along with larger graphs, but the program still wont let you maximize the window to view it in full screen.
 

Offline HoracioDos

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Re: EEVblog #315 - Korad KA3005P Review/FAIL
« Reply #348 on: April 07, 2018, 11:12:18 pm »
Well thanks for the link, but unfortunately it still has the problems I was having with the other software. The graphs are way too small and the program won't let you maximize the window to full screen. I've tried v2.5 and the window is physically bigger, along with larger graphs, but the program still wont let you maximize the window to view it in full screen.

I think that I have V2.3 somewhere. I'll let you know if I can find it. Meanwhile you might try these:
http://www.sprut.de/electronic/soft/korad/ka3005p.zip
https://github.com/crapp/labpowerqt/releases/download/v0.1.3/labpowerqt_setup_0.1.3_x86_amd64.exe
 
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Offline bitwelder

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Re: EEVblog #315 - Korad KA3005P Review/FAIL
« Reply #349 on: April 08, 2018, 07:02:56 am »
Is it possible to find anywhere only the USB control board for the KA3005P ?
Just wondering if it would be possible to upgrade a D version into a P version  :-/O
 


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