Electronics > Repair
Korad KA3005P power supply faulty/repair
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xani:
I guess lessons learned here is that if you even design a power supply, make sure it is is safe even *if* your MCU outputs "please emit smoke" combination ;D

I guess I'm lucky that only problem with my KA3005D-3S (not produced anymore, it is like 2 KA3005D glued together + 5V 3A output + option to link two to get 60V or 6A) was dodgy power switch (locked in place) and a bit loud fan
rufusalceste:
Hi Folks,

I am currently trying to repair my Tenma 72-10495 (rebranded KORAD psu) . I found the issue but I would like to replace R3 and R4 on both outputs boards as these have heated a lot and burned some of the PCB right under them. I am afraid their value is now off...
The problem is I can't manage to figure the value of these resistors (see photo attached) as the colors are pretty unclear and also because this kind of color arrangement (low value resistor ?) is new to me.
R3 seems to be black/black/silver (or is it brown/black/silver ?)
and R4 seems to be black/black/gold (or is it brown/black/gold ?)

The picture is pretty representative of what I can see with my own eyes.

If any one of you guys has a clue that would be great.

Thanks a lot !
Armadillo:

--- Quote from: rufusalceste on October 16, 2017, 01:23:06 pm ---Hi Folks,

I am currently trying to repair my Tenma 72-10495 (rebranded KORAD psu) . I found the issue but I would like to replace R3 and R4 on both outputs boards as these have heated a lot and burned some of the PCB right under them. I am afraid their value is now off...
The problem is I can't manage to figure the value of these resistors (see photo attached) as the colors are pretty unclear and also because this kind of color arrangement (low value resistor ?) is new to me.
R3 seems to be black/black/silver (or is it brown/black/silver ?)
and R4 seems to be black/black/gold (or is it brown/black/gold ?)

The picture is pretty representative of what I can see with my own eyes.

If any one of you guys has a clue that would be great.

Thanks a lot !

--- End quote ---

R1 = 1Kohm  5W
R3 = 0.1 ohm 2W
R4 = 0.1 ohm 2W
Andreas:
Hmm,

in the cirquit diagram attached here:
https://www.eevblog.com/forum/repair/korad-ka3005p-power-supply-calibration/msg370823/#msg370823

R3,R4 are 0.22 Ohms.

So could it also be red,red,gold?
Or have the values changed over the years.

with best regards

Andreas
rufusalceste:
Thanks a lot guys.

Found more info in Dave's followup video on the Korad PSU.
Seems the older version (yellow PCB) had 0.1R resistors and the newer version (green pcb ) has 0.22R resistors.
See screen grab below.

Cheers !
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