Electronics > Repair
Korad KA3005P power supply faulty/repair
<< < (18/27) > >>
Andreas:
Hello,

that is the behaviour of the device. (also on mine).
When the difference of current / voltage is below a limit the "set" instead of "actual" value is displayed.
perhaps to supress excessive flicker near cc/cv limit.

With best regards

Andreas
JackM:

--- Quote from: uv3afl on January 03, 2017, 01:06:48 pm ---I attempted to charge a 18650 battery. The process went on normally in CC mode indicating 200mA and something about 3.45 volts on battery. At that moment I thought that there was no need to give it full charge and decided to limit charge voltage to some 'long term storage' value - 3,6 volts. I have set it up and surprisingly found out that it started indicating 3.6 immediately after setting. Multimeter attached showed that actual output voltage was still 3.47V... While indicated was already 3.6.

--- End quote ---

Does the same thing occur when you attach a static load (ie. a resistor) and then put it in constant current mode?
uv3afl:
Thanks for answers.

--- Quote from: JackM on January 03, 2017, 02:37:57 pm ---Does the same thing occur when you attach a static load (ie. a resistor) and then put it in constant current mode?

--- End quote ---
I've tested this. It behaves completely the same at the static dummy resistor load.
1. Set 2V as a limit, 0,5 Amps as current limit, attach 3,3 ohm resistor

2. Load on - everything is fine

3. Change the voltage limit to 1,9 volts
4. Good bye! 1,9 instead of actual output.


Now I really interested if it is a software bug or is it a hardware design feature. And I definitely don't think that it can be normal power source behavour...
Ton:
It's a SW "feature" of the Korad power supplies (and the rebranded Tenma units), when ever the actual voltage output is within 0.2 V from the setpoint it will show the set-point instead of the actual value.  :palm:

already discussed here: https://www.eevblog.com/forum/testgear/korad-display-bug/msg585763/#msg585763

this "feature" is also seen on some cheap Chinese PID controllers, the speculation is that it gives the user a feeling of greater precision than the device actually gives.  :rant:

It is annoying but it is how these supplies have behaved, basically since they were released from Korad some 3-4 years ago.

Still I find them good value for the money even if this "feature" is irritating

Br Ton

ps. I have 3 of the Tenma branded version
pps A forum member have started the design of a alternative display PCB where this "feature" can be removed, but I dont know the current status of this, see the tread if interested.
https://www.eevblog.com/forum/projects/korad-ka3003d-redesign-and-upgrade/msg1011712/#msg1011712
uv3afl:

--- Quote from: Ton on January 04, 2017, 06:40:42 am ---It's a SW "feature" of the Korad power supplies (and the rebranded Tenma units), when ever the actual voltage output is within 0.2 V from the setpoint it will show the set-point instead of the actual value.  :palm:

already discussed here:
...
pps A forum member have started the design of a alternative display PCB where this "feature" can be removed, but I dont know the current status of this, see the tread if interested.
...

--- End quote ---
Oh, thanks a lot, Ton for proper directions! Now all further questions will be in 'right' places. And theme with alternative solution is of course of great interest! I will study that!
Navigation
Message Index
Next page
Previous page
There was an error while thanking
Thanking...

Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod