Electronics > Repair
Permanent CC and no output [Longwei K3010D]
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faza1111:
I had 3 damaged smd capacitors, I changed all of them. There was probably a bad series of all capacitors
lolocoian:
I have the same PS and after months of use it has the following problem: When going up with the knob just above 12v it start giving random but lower than 12v readings in the display. Below 12v it works just fine, i know this is really poor information but maybe you can point me in the right direction as in to what i can check. I have only checked the potentiometer and it is fine, and also checked if i have short between Drain and Source on the two Mosfets and there is no short. Thanks in advanced! :D (Ps.: i also tested terminals in the big transformer in diode mode with my multimeter and it beeps and gives 000 reading, dk if that is normal or not! )

TL084 has 12v on pin 4 and -4.22v on pin 11
Across volt pot i have 3.25v and 5.27v when display shows 10v stable when i turn the knob to more than 12v it goes to lower voltages and the reading in the display is unstable and then i have in volt pot 1.19v and 5.36v in each connector.
in amp pot i have 5.28 when in 10v stable and 5.36 when in random lower and unstable volt display

SG3525 pins when 10v stable:
1=2.25v 2=2.25v 3=0v 4=0.51v 5=2.05v 6=3.8v 7=1.97v 8=1.46v 9=0.91v 10=0v
11=0.04v 12=0v 13=12v 14=0.04v 15=12v
16=5.18v

and when things are unstable with knob turned past 12v but reading shows random voltage below 12v

SG3525 pins
1=1.7v 2=2.14v 3=0v 4=0.51v 5=2.05v 6=3.8v 7=1.97v 8=0.02v 9=0.58v 10=0v
11=0v 12=0v 13=12v 14=0v 15=12v
16=5.18v

xavier60:
Become familiar with the workings of the SG3525, https://www.onsemi.com/pdf/datasheet/sg3525a-d.pdf
Pin 16 is the 5V reference out pin. It should stay very close to 5V and not fluctuate at all.
The 5V reference supplies the top terminals of the VR and AR pots.
The wiper voltage on both pots should smoothly increase from 0V to 5V as the pots are rotated from the fully CCW to the fully CW position.
The VR pot seems faulty. One way of confirming is by swapping the pots.

Actually "Across volt pot i have 3.25v and 5.27v when display shows 10v " is ambiguous. What are you measuring the wiper voltage with respect to?
xavier60:
Pin 2 on the SG3525 should always be close to 7.5V as regulated by D4.
slntwater:
Hi everyone!

I also have a problem with my K3010D. I connected one of my LifePo4s (3,3V) with reverse polarity, the 2nd time now. After the first time, the 6A10 protection diode blew up, and everything was fine after soldering a new one. :-+

Now, after the second time (I know, i am a goat  :palm:) the PSU seems to have a short curcit in it. It won't go over 0,03V and has always 10A CC. However, the regulation works, as I can move freely from 0-0,03V (respective 0-10A). :bullshit:

All the components are looking fine, and I have no clue which components to test. Does anyone here have an Idea?  :-//

Regards
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