Korad KA3005D Digital variable power supply (bought Nov 2017) - Page 1
Forum section: electronics / general

author: Decoman
author_rank: Regular Contributor
timestamp: December 13, 2017, 10:19:21 pm
content: Being new to electronics and having spent some time wondering that variable power supply I would want to buy, I was charmed for some time by the front panel of the KA3005D and decided to go for that one, knowing such cheaper power supplies might be iffy one way or another. A similar design was reviewed in 2012 I think by EVVblog, which didn't fare well in testing at the time.As I understand it, this unit offer 5A of power at 110V and 3A of power at 220V. For a total of eh 660W max output if I can just multiply the amps with the volts. (I don't expect to ever use this much power myself or I would buy something else I am sure.)I have not yet used this thing, I have not even turned it on. I thought it could be interesting for those wondering what this thing would look like, years after they started selling this model. My impression from reading this forum and watching youtube videos, is that there seem to have been some changes, and not knowing what I would end up with, I had hoped that this unit of mine would at least be an improved version, though I can't account for any changes per se.Because I am new to all of this, I am not comfortable recommending this unit to anyone, but I thought sharing some photos could be interesting for those wondering what it might look like in 2017.The unit of mine was packed in some more or less fancy Korad packaging, sold by SRA. The box seemed to have too little glue though, as two sides came loose on packing out this thing.The unit was placed in a large zip loc bag together with a small humidity collecting bag (iirc). A manual in English, some probes and a 1m US power cable was also included, and separately packed in plastic bags.Good things so far:• Nothing rattling inside when I carefully flipped the unit around.• The buttons on the front feels ok when I press each of them.• The unit seem to have grounding wires inside, and they seem to be firmly attached with a screw and a jagged washer.• As I started to take off the top part of the painted metal chassis, I thought the screws for the chassis was fairly tight, but not too tight. (Btw, one screw on each side, rear side, also has a jagged washer.)• The fuse section of this unit, apparently has a small room containing an additional 5A, 250V glass fuse). Unsure if having some other fuse is ideal or not for a power supply connected to 230V.Bad things so far:• The "Korad" logo was only halfway printed on the front display, the lower half.• The components inside seem to have a little bit of some fine dust all over.• The strip of stripped paint on the upper and lower chassis, which I think must be the way the top chassis is grounded to the bottom part, seems a little too casual imo. Probably a good idea to tighten the screws wellSome things I've been wondering about:• Not sure what to think about the glass fuse, as I have heard that there are something called HCR fuses as well, that I naviely think of as a possible improvement, but I could be wrong.• I don't like the stripped paint parts for what might be creating a connection for ground, between top and bottom part of the chassis, maybe I could carefully remove some more paint?• I wonder how long the mechanical power button switch will last.• Will the power button safely cut the power as per design, or do I risk having the unit still output power when the power button is in the OFF state when something goes wrong with the unit?• I will guess that the fan will be somewhat loud, which I won't like. Modding the fan might perhaps not be safe I fear. The fan sucks the air out btw, I initially imagined that the fan blew air into the unit, but I guess there would be too much dust going into the unit that way.• The photos show some white paste around some components, I wonder what that is. I guess it could be some kind of special type of glue for electronics.The photos (Note, I have since taking the photos flipped the 110V switch over to 220V on the back side of the unit, and I have to buy a new "Euro"C16C13 power cable to get to use this unit anyway):

author: Terry01
author_rank: Frequent Contributor
timestamp: December 14, 2017, 12:08:26 am
content: Hi buddy. I'm new to electronics too,around a year or so but very much hobby orientated. I am teaching myself something that I know nothing about! All I have learned has been from YouTube videos and forums like this one. I love it!I bought the Tenma 30V 5A version of this power supply around a year ago. It has been fine for me learning on and although I haven't really pushed it hard or asked a lot from it,mostly just kits or breadboard stuff I would say its a good unit. I think it's quite safe too which is good for new guys. Lots of sparks and smoke and it still powers up fine after each "mistake"I hope you enjoy yours as much as I have mine.

author: bd139
author_rank: Super Contributor
timestamp: December 14, 2017, 12:16:30 am
content: Random question: How noisy is the fan on the Tenma one from your experience?To original poster - thanks for posting this. Much appreciated

author: tooki
author_rank: Super Contributor
timestamp: December 31, 2017, 02:00:40 am
content: Quote from: Decoman on December 13, 2017, 10:19:21 pmYou understand wrong. The output current is not dependent on the input voltage! This power supply is 30V/5A output. That’s 150W output, because VxA=W.The fact that it needs 3A or 5A fuses depending on the input voltage is because at the higher input voltage, it needs fewer amps to draw the needed watts (because VxA=W, so W/V=A). 120Vx5A=600W. 600W/230V= 2.6A, so they went with a 3A fuse.Basically, when used on 120V, it needs to draw more amps from the socket, when used on 230V, it draws fewer amps. But in both cases, the transformer converts it; you can think of it conceptually as the transformer converting the incoming power into abstract watts of magnetic energy, and then turning them into what it needs on the output.Quote from: Decoman on December 13, 2017, 10:19:21 pmIt tells you on the rear panel which fuse to use for the supply voltage you’re using. Do what it says!! (For you, it’s 230V, so you must insert a 3A fuse.)Quote from: bd139 on December 14, 2017, 12:16:30 amKorad makes the Tenma versions. The fan is a bit annoying, to be honest (I have the Korad KA3005P, the same as this but with USB port). I modded the housing to remove the fan grille stamped into the housing and replaced it with a separate, thin wire grille, but it made little difference; most of the noise is turbulence along the heatsink. (The fan is actually quite quiet when running in free air.)

author: Terry01
author_rank: Frequent Contributor
timestamp: December 31, 2017, 02:22:08 am
content: The fan is really quite quiet, it doesn't bother me at all. It runs very smoothly so no rattles or squeaking or anything like that, just a gentle purr. I would highly recommend it as a power supply albeit from a limited knowledge base.I've fried a few things and had sparks and smoke on a couple of occasions and its always came back on right after I've cleared the problem. Even when I've cooked a couple things on the trot it still fires up no sweat.

author: Mr. Scram
author_rank: Super Contributor
timestamp: December 31, 2017, 02:38:38 am
content: Quote from: bd139 on December 14, 2017, 12:16:30 amI have the dual output version and it's certainly not quiet. I think newer version might have a different internal heatsink which improves things. Despite this I use it a lot more than my quieter and much more expensive GW-Instek unit. I really like its utilitarian design and the simple interface of the Korad. The GW-Instek is not as convenient to use, but has a better resolution and PC control which both have their uses. It's also much better built. You can see the injection moulds of the Korad have been used to death, but I still prefer the Korad for every day use.

author: Decoman
author_rank: Regular Contributor
timestamp: December 31, 2017, 10:01:28 am
content: I wonder if the fan on my unit was supposed to be blowing air OUT of the chassis, and not into it. The fan itself has arrows on the side indicating what direction the fan is spinning and what direction the air is blowing.With the fanblowingsucking air out of the unit, like now, the fan won't blow air onto the heatsink inside. Which seems a little inefficient to me.Only good thing, might be that you get less dust inside the unit this way. Instead of sucking air into one opening, any dust included, with the fan blowing outwards, all the minor openings will suck in air instead, but with a weaker force I am sure.

author: tooki
author_rank: Super Contributor
timestamp: December 31, 2017, 01:03:58 pm
content: On mine, the fan blows out.

author: Yansi
author_rank: Super Contributor
timestamp: December 31, 2017, 01:36:25 pm
content: It seems Korad is making progress. At least they have made a custom heatsink. Remember what the first Korads had as a heatsink - i piece of a flat metal wit a parody of fins around and a fakin hell noisy fan.However it seems they cheaped out on components. My Korad is containing Nipon Chemicon capacitors as the filter (3x 2200uF/63V snapin). That was a big surprise!I have modified the cooling a bit and slowed the fan using a series resistor. Done the mod on several units since then. Currently using two of these as my main supplies.

author: kalel
author_rank: Frequent Contributor
timestamp: December 31, 2017, 01:41:52 pm
content: I would also assume it blows the air out, similar to the back fan of a computer. As for what is more effective, I don't know, but it should work as is.Warm airheat gets to the heatsink and gets out helped by the fan.It's true that computers also have a fan on the heatsink that blows inside. But some have passively cooled processors, and I would assume even in those that the fan on the back (when there is one) blows outside.

author: Terry01
author_rank: Frequent Contributor
timestamp: December 31, 2017, 01:49:37 pm
content: I'll open mine up later today and post some images of the Tenma version for comparison. I did open it when I got it for a quick nosey but can't remember off hand if it was a decent heat sink or not.I've had mine around 12 to 18 months, I got it from Farnell element 14. It'll be good to see if there are any differences inside or if they are exactly the same.It's always good to have a reason to take things apart!

author: Avacee
author_rank: Unknown
timestamp: December 31, 2017, 02:33:26 pm
content: As for why the fan pushes the air out - it's so the newly warm air isn't blown over the internals.If you are more worried about pulling dust into the enclosure then you could turn the fan around so it blows inwards and magnetically stick something like this to the back.https://www.overclockers.co.uk/demciflex-dust-filter-80mm-square-black-white-cm-000-df.htmlAll my PC fans blow inwards with these over them to create positive pressure in the case so no dust enters via all the little holes, grills, etc.Quick wipe with a lightly damp cloth or the hoover every few days and the inside of my PC case is still spotless after ~6 years.

author: kalel
author_rank: Frequent Contributor
timestamp: December 31, 2017, 03:21:36 pm
content: Quote from: Avacee on December 31, 2017, 02:33:26 pmThat's interesting, and after 6 years I cannot question you on if it works well or not (obviously it does), but if all of the fans blow inwards, where does the air escape?My understanding is that we're not supposed to have pressure inside of the case, but rather keep the airflow as good as possible (so that there is no time for heat to accumulate inside of the case). Dust can be reduced with filters, but obviously filters will also reduce airflow to a point, but a positive effect is that also noise could be slightly reduced.At least with the standard configuration, I've noticed most effect with back and back top fans blowing out, for me those are the most important fans to have, and to have good airflow capabilities. I've noticed much less effect with added side fans or front fans (with front fans blowing in, and side fans depending on the side). This will depend on the case of course. Some cases just offer better cooling with the same amount of fans than others.

author: Mr. Scram
author_rank: Super Contributor
timestamp: December 31, 2017, 04:43:16 pm
content: There's still a huge discussion whether positive of negative pressure, as far as you can speak of that in a PC case is more effective against dust. However, from a cooling perspective, people generally agree that there should mostly be a balance between intake and outtake. This seems to be confirmed by experiments done by people. Some do this by slowing the fans on one side down or by adding or removing a fan on intake or outtake.If you have all fans pointing in or out cooling will suffer, which is obviously ultimately the point of having fans in the first place. If you absolutely want to fight dust you could remove all fans completely, but that's not a good idea for the same reasons. The truth is that a proper airflow will contain more dust than an improper airflow, simply because the volume of air is bigger, and will likely carry more dust inside your case because of it.

author: Kleinstein
author_rank: Super Contributor
timestamp: December 31, 2017, 05:51:50 pm
content: The heat sink looks much better than the old version. Using an extra board for the power resistors also looks odd, but I would guess it works.The "coil" near the output terminal looks a kind off odd - this might be the current shunt made from something like a maganin wire. I have seen worse.

author: Yansi
author_rank: Super Contributor
timestamp: December 31, 2017, 05:56:19 pm
content: Yes, that is the output shunt.Whats is wrong with that?

author: Mr. Scram
author_rank: Super Contributor
timestamp: December 31, 2017, 06:27:26 pm
content: Quote from: Kleinstein on December 31, 2017, 05:51:50 pmMany devices do it that way, many of which are of a reputable make.

author: stj
author_rank: Super Contributor
timestamp: January 01, 2018, 05:27:50 pm
content: throw the cables away.

author: tooki
author_rank: Super Contributor
timestamp: January 02, 2018, 02:45:52 am
content: What do the junky cables that come with a random chinese PSU have to do with the ones that come with this specific non-random model?

author: stj
author_rank: Super Contributor
timestamp: January 02, 2018, 05:06:53 am
content: take a close look at the pictures posted above.it's the same chinese cables.

author: Decoman
author_rank: Regular Contributor
timestamp: January 02, 2018, 12:22:05 pm
content: What is an 'output shunt'? I mean, what is its intended purpose there?Btw, the detachable power chord for 110V that came with my unit was replaced with a locally bought 220V power chord (says "250VAC 10A" on it).

author: bd139
author_rank: Super Contributor
timestamp: January 02, 2018, 12:23:09 pm
content: It's a small resistor that is used to measure the output current with the relationship I = V/R. You know R, so you can derive I from measuring V.Everything from Chinese power supplies to high end Flukes use bent bits of wire for this job

author: Decoman
author_rank: Regular Contributor
timestamp: January 02, 2018, 12:39:54 pm
content: Btw, the power supply unit that is shown in stj's video, seem to have its fan arranged to suck air into the unit. Just an observation.* watching the end of that video linked above* Oh, wow. The tester things that non copper was used, and instead "copper plated aluminium" for all the strands of metal inside that psu's wire cable. :O

author: tooki
author_rank: Super Contributor
timestamp: January 02, 2018, 04:28:42 pm
content: Quote from: stj on January 02, 2018, 05:06:53 amThe power cords obviously are not the same, since they’re not even for the same country.As for the alligator clip leads, they could be the same, or they could be entirely different inside — it’s impossible to tell without dismantling them. (My Korad didn’t come with alligator clip leads so I can’t volunteer to do this.)

author: stj
author_rank: Super Contributor
timestamp: January 02, 2018, 04:56:22 pm
content: factory's churn out power cords for lots of country's - they dont each come from a seperate source.anyway, it looks like you can spot them with an ohm-meter.so that makes it simple to check.

author: Terry01
author_rank: Frequent Contributor
timestamp: January 02, 2018, 05:00:23 pm
content: Quote from: Terry01 on December 31, 2017, 01:49:37 pmI am loaded up with the flu and cannot be bothered stripping out my PSU! I will post said photos in the next day or 3 when i'm feeling more enthusiastic. Crap!

author: stj
author_rank: Super Contributor
timestamp: January 02, 2018, 08:05:49 pm
content: you need to sterilise your bloodstream.i like vodka myself.

author: tooki
author_rank: Super Contributor
timestamp: January 03, 2018, 10:11:29 pm
content: Quote from: stj on January 02, 2018, 04:56:22 pmWell yes. But what makes you think that there's only one factory making power cords? (And that those factories only make one grade of cord.)Quote from: stj on January 02, 2018, 04:56:22 pmA wise precaution in any case!!!

author: lt_cdr_data
author_rank: Newbie
timestamp: May 22, 2018, 01:51:05 pm
content: Hi, the light blue resistor R3 is blown on my device (mounted on the upper edge of the board close to the fan connector) could you tell me it's value, so i could replace it.﻿ TIA

author: Mr. Scram
author_rank: Super Contributor
timestamp: May 22, 2018, 03:36:27 pm
content: Quote from: lt_cdr_data on May 22, 2018, 01:51:05 pmCan you show it in a picture?

author: Terry01
author_rank: Frequent Contributor
timestamp: May 22, 2018, 07:01:00 pm
content: Quote from: lt_cdr_data on May 22, 2018, 01:51:05 pmR3 is.... 10 Ohms 1% buddy.

author: lt_cdr_data
author_rank: Newbie
timestamp: May 23, 2018, 05:19:29 am
content: Thank's dude, could you guess the wattage of it as well? Cause I have really no clue how it can burn off like it did in my case. Did not found any schematics to read off it's purpose in the circuit. BR

author: Terry01
author_rank: Frequent Contributor
timestamp: May 23, 2018, 06:55:11 am
content: Quote from: lt_cdr_data on May 23, 2018, 05:19:29 amI'd guess 3W.

author: ziplock9000
author_rank: Regular Contributor
timestamp: May 30, 2018, 06:52:31 am
content: Quote from: kalel on December 31, 2017, 03:21:36 pmThis is a "solved" problem and not really open for debate with PC cases and hasn't been for quite a while.The best case setup has fans pushing air in and pulling air out. The ones pushing air in should have more power then the ones pulling out to create positive air pressure and reduce dust (considerably). These fans have an air filter attached. The fans pulling air out should be near the CPU heatsink and create a clean path from the fans pushing air in. You can add more fans that support this arrangement that target specific areas in the case, for example moving air from the GPU into the in-out stream, but they are all variations on this theme.

author: ziplock9000
author_rank: Regular Contributor
timestamp: May 30, 2018, 06:56:46 am
content: Quote from: Terry01 on May 23, 2018, 06:55:11 amSo do you consider this still to be the best price/performance cheap digital bench power supply in the UK?

author: Terry01
author_rank: Frequent Contributor
timestamp: May 30, 2018, 07:48:43 am
content: Quote from: ziplock9000 on May 30, 2018, 06:56:46 amI don't know about the "best" in the UK but a very good hobby PSU in my limited opinion. To be the "best" you have to look at so many different things I know too little about.There are so many to choose from and I don't know enough electronics wise to say one is better than another for whatever reason.I know I still love mine after a couple years of good solid use. It's still quite accurate and the fan doesn't squeak or rattle so it's still very quiet.All the safety features still work as they should and that part I have tested to the limit i'm not too proud to admit!I would certainly recommend it to anyone looking to buy 1. I have no complaints at all with mine. I found it easy to use and learn how to get the most from it and found it very forgiving as I made lots of newby mistakes. There are a few guys here on the forum have them too and can usually tell you how to fix it if needed or open theirs to help get parts numbers or whatever.At a guess it has to be up there with the best surely.

author: ziplock9000
author_rank: Regular Contributor
timestamp: May 30, 2018, 07:50:25 am
content: One major thing that worried me about that one, even for hobby use is the spike/inrush when it's turned on. Some people were saying they were substantial. Have you tested yours on a scope?

author: Terry01
author_rank: Frequent Contributor
timestamp: May 30, 2018, 08:06:07 am
content: Quote from: ziplock9000 on May 30, 2018, 07:50:25 amI have had it on my scope but that was a while ago but i can't remember anything that jumped out at me. I can't even remember why i had it hooked up to start with, just tinkering with something else i think so hooked the PSU up too as it was there and I hadn't done it before. I will certainly hook it up the next time i have my scope out. I keep it boxed up when i'm not using it as i am a bit tight for bench space right now.I'll post here what i find.I know that i have never fried anything due to spikes on start up before.I have the Tenma version so it would be good to check if they are exactly the same or just a straight re-badge or if anything is different inside.It might be a good idea to get some decent photos up of both units and see if there are any differences between them.