Electronics > Repair
Korad KA3005P power supply faulty/repair
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electricar:
Hi folks,

does the newest revision of the PSU have those overshoot issues too? I bought the Korad KA3005P recently and have overshoots when enabling the output. Unfortunately, I didn’t look up the revision of the PSU yet.
milamber:

--- Quote from: mos6502 on October 23, 2013, 12:05:03 am ---Right. But they could also be level shifters/buffers for the R2R DAC. IMHO the 100ms transient response (no opamp is THAT slow) and the steps in the voltage after turn-on (watch Dave's video) speak a clear language.
Unfortunately Dave didn't do a transient test. Anyone who owns one of these want to do one? All you need to do is to connect a big resistor to the output and switch it with a MOSFET at ~100 Hz and trace the output voltage on a scope.

--- End quote ---

Is the Atmel clocked with a 12 MHz quarz? Did someone already try to exchange it with a 16MHz or 20MHz to tweak the transient response to 75 or 60ms?
Andreas:

--- Quote from: electricar on February 15, 2016, 10:19:41 am ---Hi folks,

does the newest revision of the PSU have those overshoot issues too? I bought the Korad KA3005P recently and have overshoots when enabling the output. Unfortunately, I didn’t look up the revision of the PSU yet.

--- End quote ---

Hello,

I have around 8% overshoot on the 5V setting.

With best regards

Andreas
oger:
Hi everyone,

I also have this Powersupply. I have a later date, so I don't need to deal with a lot of the issues discussed here.m But I did a mod that prevents the fan from spinning permanently.
I do have however two things that bother me.
First is that the supply seems to have a capacitor at the output. I could not source a schematic so I'm not sure.
The problem is that when I connect an led for example and have the output voltage set to anything higher than 7 or 8v it will be destroyed because
current limiting did not kick in quick enough even though I set it for less than 10mA.
This might be a common problem among PSU though. I'm not sure.

Secondly, what bothers me the most is that the rotary knob for setting voltage and current behave erratically.
When I turn it, it might jump to 25v right away. Very dangerous when the output is on.
So I wonder if I could just replace the digital "pot" or is it the logic behind it at fault?
This gets progressively worse.

Thanks for info!

Stefan
Dominic-V:
Just disassemble the rotary knob and clean it with isopropyl alcohol, then lube it and put it back in. Should work as new, at least mine did and never missed a digit after.

As for the current limit, just connect the led before turning the output ON.
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