Korad KD3005P Problem with current metter

[PsiSoP]

I am a beginner so please suffer my question with patience.
I'm but old one cheapest PSU - KORAD KD3005P
I have firstly problem with strange load. Immediately after turning on it shows 0,453-0,432 Ampere consumption, although nothing is connected to the output Clem.
The problem disappears if I increase the voltage of about 15 volts above.
this short video about this problem  in shop.
https://youtu.be/y98YsndyNFQ
And at home
https://youtu.be/KzRhk3tji20
After this i`m try to find some circuit board schematic - some find here and some on other forum and fix this.
The reason for reading ammeter persists that that there was a small short circuit the terminals 5 and 6 on the connectors J1

Next problem - But now Amperemeter shows 0,000 until the load is applied above 0.300 mA. The difference readings of the ammeter and Multimeter, the higher the higher the current flowing in the circuit.

After some time, I'll post a video of the second problem. at the moment I want to get some sleep after many hours spent in the intrigues of the problem.
The essence of the second problem in zero reading ammeter.
I connected the fan from the computing system with consumption of 120mA but somewhere on the ammeter were zeros.
I thought that it did not work. But incorporating tester test current I limited leaving the power supply current of 1A and the meter showed 0.998 A but ammeter Power supply mode showed approximately 0.72 *
Now I'm a little confused with the strange fan speed adjustment system that in some way affect the reading of the ammeter power supply through the point of connector J1-6.
I could not find exactly Electric scheme for Korad KD3005P I used pieces of similar schemes from Korad KA3005D.
Now you can hurling slippers at me for my bad English and inconsistent explanation of the problem.

Thanks in advance and await your comments!
Thanks for your patience in advance!

Have a nice day! or night )

Best Regards

[PsiSoP]

oh sorry - couple photo of my PSU

[singapol]

Hope these schematics help...

[PsiSoP]

Hope these schematics help...

I could not find exactly Electric scheme for Korad KD3005P I used pieces of similar schemes from Korad KA3005D

Thank you very much for your response but as can be seen by quoting them, I already have.
I'm looking for Korad KD3005P they differ little circuitry.
You will be glad to any ideas for repairs.

Best Regards

[PsiSoP]

Hi
I was able to find some documentation of the calibration of the power supply KORAD KD3005*. Maybe my problem is a broken gauge? Should I try to calibrate or standing still to look for cause of the problem?

Best Regards

[Kleinstein]

There is a chance that initial problem cased a wrong calibration. So fixing the zero point trouble might need a new calibration. At least it could be worth a try. The calibration of such a low end supply should not be supper high precision and thus should be doable.

[PsiSoP]

There is a chance that initial problem cased a wrong calibration. So fixing the zero point trouble might need a new calibration. At least it could be worth a try. The calibration of such a low end supply should not be supper high precision and thus should be doable.

Hello
I did defeated him !!
After some hesitation on my actions with respect to this power supply - I came to the conclusion that the last owner because of oxidation of the contacts in the connector, he came out of the operating state and the old master, instead of trying to find the cause and fix it tried to calibrate it. Which led to such problems.
I am very happy that I was able to fix it and get a great experience for a device of this power supply.

Here are some videos from the readings after calibration.
I'm not sure of the veracity of of my Multimeter this is not much to draw attention to some inaccuracies in the readings of the instruments.
You'll be glad like the proposals to increase the accuracy of the instrument.
https://youtu.be/zon7xrRTj68

[Kleinstein]

Looks like there is still a minor (e.g. 1% range) difference of the current reading on the supply and the meter. But this is nothing to really worry about.

It is strange how fast the fan reacts to changing load - sound like it is nearly instant. It the fan controlled by the measured current and not the measured temperature ?