Author Topic: EEVblog #315 - Korad KA3005P Review/FAIL  (Read 251937 times)

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Offline KORAD TECHNOLOGY

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Re: EEVblog #315 - Korad KA3005P Review/FAIL
« Reply #175 on: November 11, 2012, 11:43:32 am »
... Dave to post the good video review very soon.  :)

Can't wait to see THE GOOD VIDEO. However, I have the feeling you will be a bit disappointed.

Thanks for your reply. I sincerely hope I won't  :)

It will depend entirely upon the performance of your product. Dave will give it a fair call, if the problem is gone and the fix looks permanent you may get something like the review you wish for.
 Ignore the talking heads in the cheap seats any review will be a fair call of the product as presented.

Hello, Uncle Vernon, thanks a lot for your support.   ^-^ I also believe Dave will give a fair call. Charles has made a good video and will post next week after he gets the repairing boards for his current 16PCS stock. Have a nice evening!
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Offline Bored@Work

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Re: EEVblog #315 - Korad KA3005P Review/FAIL
« Reply #176 on: November 11, 2012, 11:55:00 am »
...

No sorry kid, you lost your drive when you started to resort to spelling error correction postings to establish your superiority. And then you come up with racism accusations. Carefully chosen because it is nearly impossible to defend against such an accusation. By the way, did you clear that one with the leader of my fan club, Private Fluffer? He might be a bit upset if you didn't run it by him before posting.

By the way, have fun with a response. Guess what I'll do with it?
I delete PMs unread. If you have something to say, say it in public.
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Uncle Vernon

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Re: EEVblog #315 - Korad KA3005P Review/FAIL
« Reply #177 on: November 11, 2012, 12:01:18 pm »
Hello, Uncle Vernon, thanks a lot for your support.   ^-^ I also believe Dave will give a fair call. Charles has made a good video and will post next week after he gets the repairing boards for his current 16PCS stock. Have a nice evening!
I am not offering any particular support other than a sense of fair go, if the modifications to your supply are sufficient, I can see no reason why some of the initial enthusiasm for it cannot be revived.
I trust calls Dave or Charles will make and see it as ignorant that some will condemn on no basis other than country of origin. There is interest, by some,  in a follow up video, but as always it will be Dave's call what is produced and released.
 

Uncle Vernon

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Re: EEVblog #315 - Korad KA3005P Review/FAIL
« Reply #178 on: November 11, 2012, 12:11:37 pm »
No sorry kid
Haven't heard that one this century. Almost a compliment,  :)

Quote
to establish your superiority
It is heartening to see you have recognised this superiority, but there is no need for you to make any fuss, if you bow as I enter the room and covet your eyes, that will be entirely sufficient.

Quote
And then you come up with racism accusations.
A perfectly reasonable response towards repeated racism..

Quote
Carefully chosen because it is nearly impossible to defend against such an accusation.
It will be given your repeated racist remarks are embedded in all manner of caches and backups by now.

If someone who is simply bored at work and has nothing better to do than conjure up speculative crap about what the Chinese thought,

You work for Trio, don't you? But anyhow, feel free to kiss my arse any time it is convenient for you.

Oh, and I deal regularly with Chinese companies and engineers. Bunch of liars, all of them.

Quote
By the way, have fun with a response. Guess what I'll do with it?
If this is a lead-in to another of your rectal activities posts, then I'll choose not to guess thanks all the same.

Be nice to others.  ;)
« Last Edit: November 12, 2012, 02:27:37 am by Uncle Vernon »
 

Offline LaurenceW

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Re: EEVblog #315 - Korad KA3005P Review/FAIL
« Reply #179 on: November 11, 2012, 12:34:54 pm »
I imagine that BAW's bed is up on six foot stilts, so that, whichever side he gets out of it, it's always the wrong side and leaves him fuming at the rest of humanity for the whole day, as a result.

I reckon
If you don't measure, you don't get.
 

Offline KORAD TECHNOLOGY

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Re: EEVblog #315 - Korad KA3005P Review/FAIL
« Reply #180 on: November 11, 2012, 01:56:22 pm »
SO I'm confused.  Was Dave's unit a pre-production model that has since been fixed?  Or is there a flaw in all of the units on the market?

Call me crazy but I'm still considering buy one, if I can just confirm that the issue has been fixed or not.


Hi George, it is an early shipment(NOT a flaw) due to a few defective transistors. And now this issue has been fixed. The units  sent to our other representative are good and sell well. After Charles (Trio Smartcal) gets the boards to fix his current 16PCS stock, you can buy from him.  :)    Thanks for your support in advance!
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Offline Bloch

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Re: EEVblog #315 - Korad KA3005P Review/FAIL
« Reply #181 on: November 11, 2012, 08:58:33 pm »

it is an early shipment(NOT a flaw) due to a few defective transistors. And now this issue has been fixed.
Is that the transistor on the back pcb ? Or are there more ?


After Charles (Trio Smartcal) gets the boards to fix his current 16PCS stock,
This is great! Can you upload here the old and the updated service manual (with schematic) ? So we can see that is updated ?
 

Offline TRIO_Smartcal

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Re: EEVblog #315 - Korad KA3005P Review/FAIL
« Reply #182 on: November 13, 2012, 06:29:49 am »
Hi everyone, I received the modified power supply from Krissy at Korad just over a week ago.  So the first thing to do was to try and blow it up or burn it out to appease the trolls and for the interest of the more curious folks watching the thread.  In a nutshell I failed. The thing is still sitting beside me here with its output current-dependent fan going flat out.

What it was subjected to was:
- Set to 31.00V 5.100A and shorted the output. Left running for about 3 hours.
- Output shorted and the output switched on and off rapidly
- tried to use it as an arc-welder to stick the DMM probe to an alligator clip
- ran it at close to 150 Watts for about 5 hours
- rapidily switch the output on/off set to 31V 5.1A and a load connected
- ran it at 1V, 5.1A into a short circuit for 3 hours (this was more interesting from the current measuring DMM perspective...)

In summary, as we say here in Aussie-land the results were "as boring as bat-sh*t."  The thing is still working. I have never seen bat-sh*t, but I can endorse the validity of the adjective used in the comparison to a working power supply in steady-state conditions.

I did get that nice smell of warming plastic from the insulation on the alligator clips connected to the load. But nothing more spectacular than that.
I took a few thermal images of it too. Before I get trollisitc comments..  these were taken with the cover on because the cover forms part of the forced air cooling path. Highest temp I could see was about 77 degC on the transformer when it had been running at full load for over 2 hours. I'll upload those thermal images in the next post.
The one in this post is the power supply feeding the 10A input on a DMM.  It did this continuously for over 3 hours today and had no problems with being switched on and off rapidly.  You can see the area on the DMM where its fuse sits just behind the front panel. You'll see in the video, whenever I get it loaded, that this warming affects the DMM reading.  And before anyone comments, the DMM's had auto-powered-down and I'd got bored turning them on over and over again.


« Last Edit: November 13, 2012, 12:02:06 pm by TRIO_Smartcal »
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Offline TRIO_Smartcal

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Re: EEVblog #315 - Korad KA3005P Review/FAIL
« Reply #183 on: November 13, 2012, 07:13:59 am »
Here's some of the thermal images taken after the Korad KA3005P  had been running for a while.   

In the process I tried a couple of DMM's for the current measurement to see which warmed up the most and to see if it was possible to see where the internal shunt and fuse was without opening them. I'd got bored with the power supply at this stage. 

Anyway, I couldn't blow it up so when we get the parts to repair those we have in stock, they will go back on sale with a 2 year warranty.  If anyone wants to buy one, just mention EEVblog and we'll chuck-in at no charge a set of DMM test leads so you can use your old ones as welding rods....

http://triosmartcal.com.au/1713-tl-104-test-leads--alligator-clip-cat-iv-600v--cat-iii-1000v.html
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Offline TRIO_Smartcal

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Re: EEVblog #315 - Korad KA3005P Review/FAIL
« Reply #184 on: November 13, 2012, 07:55:29 am »
The warmed up DMM's are in the thermal pic's below.  These were an Agilent U1233A and an Agilent U1241A. I used a U1252A to keep an eye on the voltage.
During the soak-testing the current reading on the DMM's used to measure current steadily increased as they warmed up.
The power supply current reading did not change much at all. The voltage reading crept up marginally.
As most of you are probably aware, a DMM measures current by measuring the voltage over an internal shunt.
So what we were seeing with the slowly, but steadily, increasing reading on the DMM's was the internals of the DMM's getting warm, the internal resistance increasing with this temperature rise and the power supply giving a bit more voltage to keep the current at max.  The test leads will also play a part in this resistance path. We can see that the resistance of the leads and the DMM input is a combined 0.1 Ohms.

The normal picture below shows the DMM after it had been running for a while and the current reading had drifted up a bit. This was while we were testing at a setting of 1V, 5.1A.  The power supply went to constant current mode to deliver its max current and the compliance voltage necessary for this (0.5465V) is displayed on the U1252A.

It would have been more interesting if it hadn't all behaved as expected, but all ended up as hoped for.
We still have a working power supply and I got to play with a thermal camera.......
 ;D
« Last Edit: November 13, 2012, 08:15:10 am by TRIO_Smartcal »
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Offline EEVblogTopic starter

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Re: EEVblog #315 - Korad KA3005P Review/FAIL
« Reply #185 on: November 13, 2012, 09:15:17 am »
Awesome follow-up, thanks Charles!

Dave.
 

Offline SeanB

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Re: EEVblog #315 - Korad KA3005P Review/FAIL
« Reply #186 on: November 13, 2012, 05:00:08 pm »
Are you going to send a board to Dave to do his unit? Will be interesting to see the comparison and how it looks.
 

Offline Bloch

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Re: EEVblog #315 - Korad KA3005P Review/FAIL
« Reply #187 on: November 13, 2012, 05:03:36 pm »
Are you going to send a board to Dave to do his unit? Will be interesting to see the comparison and how it looks.


Not possible - Dave send it to hell or there about[size=78%] [/size] :-DD
 

Offline TRIO_Smartcal

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Re: EEVblog #315 - Korad KA3005P Review/FAIL
« Reply #188 on: November 13, 2012, 09:43:38 pm »
Dave sent the blown-up unit back here. Whenever we get the parts from Korad to fix it I'll take a few pics of any modifications and post them here.
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Offline EEVblogTopic starter

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Re: EEVblog #315 - Korad KA3005P Review/FAIL
« Reply #189 on: November 14, 2012, 11:56:14 am »
And here is Charles's video of of testing the new supply:


Looks pretty comprehensive, and if that abuse didn't kill it, I'm not sure what will.
Nice work Charles!

Dave.
 

Offline nitro2k01

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Re: EEVblog #315 - Korad KA3005P Review/FAIL
« Reply #190 on: November 14, 2012, 12:30:43 pm »
if that abuse didn't kill it, I'm not sure what will.
My own personal theory is that the error condition in the original test was produced by a race condition with the load. For example, the load is able to repeatedly overload and de-overload the supply very quickly such that the total current that passes through the supply through multiple pulses is enough to destroy something. Or, there's a comparator which triggers an interrupt on the microcontroller, which is triggered multiple times. This makes the microcontroller's interrupt stack to overflow, or something like that.

My point is, I would want the same scenario, with the electronic load, to be tested before giving the new unit the thumbs up.
Whoa! How the hell did Dave know that Bob is my uncle? Amazing!
 

Offline SeanB

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Re: EEVblog #315 - Korad KA3005P Review/FAIL
« Reply #191 on: November 14, 2012, 12:43:57 pm »
Send it through the postal service wrapped in brown paper, that will destroy it.

Nice test, though I would like to see it being run until it does a thermal shutdown into a short circuit or into a 12V lamp in CC mode.

Is it me or does the micro stop scanning the display when changing voltage, leaving an arbitrary digit running at full power while doing so. It would be better for the firmware designer to blank the display when doing this, to keep from burning out the display digits.
 

Offline Stephen Hill

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Re: EEVblog #315 - Korad KA3005P Review/FAIL
« Reply #192 on: November 14, 2012, 12:59:11 pm »
Do you expect Porsche experience when you buy a KIA as well. Wouldn't be much sense in making Porsche's if that was the case.

KIA's come with a 7 year warranty...
 

Offline deephaven

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Re: EEVblog #315 - Korad KA3005P Review/FAIL
« Reply #193 on: November 14, 2012, 01:10:55 pm »
One of the most important specs on a lab power supply for me is to never overshoot the set output voltage so as to avoid zapping the circuit it is powering. Would it be possible to do some of those tests with a scope attached?
 

Offline HackedFridgeMagnet

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Re: EEVblog #315 - Korad KA3005P Review/FAIL
« Reply #194 on: November 14, 2012, 01:30:19 pm »
Quote
My own personal theory is that the error condition in the original test was produced by a race condition with the load. For example, the load is able to repeatedly overload and de-overload the supply very quickly such that the total current that passes through the supply through multiple pulses is enough to destroy something. Or, there's a comparator which triggers an interrupt on the microcontroller, which is triggered multiple times. This makes the microcontroller's interrupt stack to overflow, or something like that.
I agree with Nitro. I think.

When I saw the video of the fault occurring,  I had a thought along the same lines, ie. Constant watt load (if I remember rightly) and some sort of diverging control interaction going on between the two units.
Reproducing the circumstances of the failure so the new version could be tested under these circumstances would be a good validation of any fix.
If anyone could be bothered.
 

Offline george graves

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Re: EEVblog #315 - Korad KA3005P Review/FAIL
« Reply #195 on: November 14, 2012, 05:14:13 pm »
A follow up would be nice.   8)

Offline TRIO_Smartcal

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Re: EEVblog #315 - Korad KA3005P Review/FAIL
« Reply #196 on: November 14, 2012, 11:03:35 pm »
Do you expect Porsche experience when you buy a KIA as well. Wouldn't be much sense in making Porsche's if that was the case.

KIA's come with a 7 year warranty...

If you'd like me to raise the price to that of a Kia you can have a 99 year warranty   ;D
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Offline TRIO_Smartcal

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Re: EEVblog #315 - Korad KA3005P Review/FAIL
« Reply #197 on: November 15, 2012, 04:59:08 am »
Dave has posted a very amateurish video about our attempt to burn-out the Korad version 2.

It's a summary of the attempt. Obviously the video does not show the 12 or so hours we had it running for during the burn-out test.

Here's the link:  http://www.eevblog.com/2012/11/15/korad-psu-follow-up/

If you fall asleep during it that's OK, it's a power supply after all.  No car headlamp bulbs or items of test equipment were injured in the making of this video. We tried though.......
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Offline BravoV

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Re: EEVblog #315 - Korad KA3005P Review/FAIL
« Reply #198 on: November 15, 2012, 05:24:09 am »
What happened to other customers who bought this thing say from ebay type of deal ?  :-//

So practically they're screwed ?


Offline george graves

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Re: EEVblog #315 - Korad KA3005P Review/FAIL
« Reply #199 on: November 15, 2012, 05:42:26 am »
How can we tell the difference? between the old model and the new "fixed" models? I'm in the US - and would prefer to buy from a US seller.


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