KORAD 3005D

[Hostar]

Hello everyone,
I am a new member on the forum and first of all I greet you all nicely.

I recently purchased a KORAD 3005D PS. Right from the start, I had a bad feeling when I noticed a broken green earth connector. Not the worst case, but a more serious problem is that despite the calibration, the display shows 50mA less output current than it really is. It is NOT range dependent, if I set the max current to 50mA, the output is exactly 50mA, but the display shows 0mA. So even when I set the max current to 1A, the output is 1.003A, but the display shows 952mA. The same story is at 5A.
Reading the forum I found all the schematics. A detailed inspection of the board showed nothing special, however I resoldered the pins on the operational amplifiers (TL082), but there is no change. I don' t know if I understand the schematics, but I think that AD1 and AD2 are the analog inputs to the mPC to somehow display the "set" value and the measured value of the current ? Not sure, but I rather repair that and learn something, than communicate with sales on Aliexpress for returning and spend money for shipping.
Any help or hints are very welcome  .   

[Andreas]

You should search for the "calibration procedure" (somewhere here in the forum).

with best regards

Andreas

[Hostar]

Thanks Andreas, calibration was the first thing I did try.
Well, I think I had a bad luck with this order  . Calibration works fine on min and max Voltage settings and also I can set minimum mA current, but when I try to switch to max current settings with M4 button, the display shows 1.5A and nothing changes with rotary knob spinning. I also try to change shunt resistor, but it is the same story.
Strange thing is, that real output current is correct, just display shows incorrect value, exactly 50mA less than it was set.
Just wonder if anyone else has the same problem?