Electronics > Repair
Korad KA3005P power supply faulty/repair
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cavlovic:

--- Quote from: mos6502 on October 25, 2013, 12:09:27 pm ---
--- Quote from: KORAD TECHNOLOGY on October 25, 2013, 04:04:49 am ---This is Krissy from KORAD TECHNOLOGY. Would you please kindly send me your e-mail address? I want to solve it soonest. Thank you in advance!

--- End quote ---

What is your policy regarding schematics? Can you give them out or not?

--- End quote ---
She was very prompt with email and very kind. She asked for pictures of the display fault, but in return will provide and ship new board to me. I just made a short video which I will share here also, when done uploading.

The support is really good and means a lot to me, especially for future purchases.

They also sent me latest version of software in English (currently downloading - will report later), without me even asking! I guess they took time to read through all posts. I will share it with others once I check with them that it is OK thing to do.

I'm very satisfied with response so far!
Flump:

--- Quote from: KORAD TECHNOLOGY on October 25, 2013, 04:04:49 am ---This is Krissy from KORAD TECHNOLOGY. Would you please kindly send me your e-mail address? I want to solve it soonest. Thank you in advance!

--- End quote ---

This is really nice to hear, I need to get a new power supply soon.
I may well consider a Korad unit now.

big thumbs up from me  O0
cavlovic:

--- Quote from: Flump on October 25, 2013, 05:17:13 pm ---
--- Quote from: KORAD TECHNOLOGY on October 25, 2013, 04:04:49 am ---This is Krissy from KORAD TECHNOLOGY. Would you please kindly send me your e-mail address? I want to solve it soonest. Thank you in advance!

--- End quote ---

This is really nice to hear, I need to get a new power supply soon.
I may well consider a Korad unit now.

big thumbs up from me  O0

--- End quote ---
Yes, very nice to hear they take care of customers after sales, even though they sell cheap power supplies.

In last email I asked her about some firmware upgrades, that could improve usability, and will let you all know about the response. I also asked her about schematics and publishing of it.
van-c:
Back in June I purchased a KA3005P from SRA Soldering.  It has been a reliable power supply that is easily calibrated to within Korad's published specs using the procedure I posted in reply #7.  However, there is a bit of an issue that I've seen on mine (and observed on others in videos) that causes the outputs to produce a very low negative voltage when the output switch (not the power switch) is set to the OFF position.  With no load on the output terminals I measure between -107 mV and -115 mV until the output switch is pressed ON, at which point the measured output becomes about equal to the displayed output voltage.

I've discussed this with SRA soldering, who have swapped out an entire unit for me, and recently sent a replacement board, to attempt to fix the issue.  After I replaced the microcontroller board, the no-load output changed slightly, from -108 mV to -115 mV.  But basically, the issue still remains.  Under loaded conditions, I measured the following voltages : 2200 Ohms: -73 mV; 1000 Ohms: -53 mV; 100 Ohms: -10 mV.  This is obviously not a serious problem, but I would expect a properly designed switched output to produce zero volts across the output terminals whenever the output switch is OFF.

Although the issue is still present, I must say that once again, SRA Soldering has done a superb job of customer support.  They paid for shipping my original unit back to them, sent me a new replacement unit without charge, and finally, sent a replacement board all in an effort to fix the issue.  I told them I am willing to just consider this issue a quirk of this particular supply, but they have continued to show an interest in resolving it.

Now that Korad has popped up on this thread, I thought they may want to take the opportunity to chime in on this.  Is Korad aware that the KA3005P produces over 100mV on the output terminals even when the output switch is turned off?  Is this considered normal behavior for this particular model?

--Van
pomonabill221:
I did rev eng the power supply and have drawn (hand drawn) the schematic.
I can scan it and create a pdf for your dining and dancing pleasure, but I want to make sure that I won't get in trouble with Korad for publishing it here.
If Korad reads this please let me know if I can post, OR better yet, post the official schematic for us!
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