Korad KA3005P Low Current Startup Problem

[hgg]

Hi,

Is this normal ??
https://youtu.be/9DwytzdpQOc

You cannot switch on the output with a 17mA current limit.
With 18mA it ramps up.  I guess the output capacitors, but zero output with anything less.

Any ideas or someone else with a similar problem?

Thanks.

[ProBang2]

Hello.

Your video is marked as "private", hence not visible.

I can enable the output of my KA3005P even with 1 mA current set.
Output checked with DMM: ~ 0.8 mA (regard the burden voltage)
Which kind is your load?

Do you are using the normal "current control" (so there is no problem)?
Or the specific current limit setting ("OCP")?

The OCP is supposed to shut down the output if the given limit is reached (even with a short spike).

[hgg]

Oops, it should be ok now.  Can you check?

No OCP or OVP enabled.
It does the same with a load and without.

So, there must be some kind of damage.
It used to start up with 1mA as well.

[ProBang2]

It seems, it does not matter if a load is connected.
Starting output at 1 mA, at 17 mA and every value inbetween.

Tested: Open circuit, DMM (measuring mA) and with a resistive load (a simple lightbulb).

I have no clue, why your PSU does not start? 



BTW: Your video is visible now. Right now seen it. Strange ...

[hgg]

Hmmm, I might have to open it to see if there is something obvious.

[Kleinstein]

It might be a rather offset of about 17,5 mA, so anything less than 18 mA set might actually be a 0 mA (or negaitve) current limit.

As a test, one could measure the maximum current with low settings (e.g. 18 mA , 20 mA).

[hgg]

When I measure the current with the multimeter its the same as the value shown on the Korad display.

Just played with its current calibration and now it is able to start from 3mA. 
Still cannot do 2 or 1mA.   Strange.