Author Topic: Inside the new Korad KA3305P linear PSU  (Read 58934 times)

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Offline crispy_tofu

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Re: Inside the new Korad KA3305P linear PSU
« Reply #75 on: October 21, 2015, 01:24:24 pm »
Just saw this teardown, looks nicely laid out. Thanks for satisfying my teardown urges!  :-/O
 

Offline Gall

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Re: Inside the new Korad KA3305P linear PSU
« Reply #76 on: October 22, 2015, 01:22:33 am »
Why? I'm not saying you are wrong, I just don't understand what makes you suspect that. I don't think there is a lot of HF radiation from either board, it's a linear supply and the regulation seems to be at the other end of the PSU.
I just suspect that this may be sensitive to the EMI from i.e. the device under test. My old Mastech power supply used to show negative (!) current values in the presence of a small 100 MHz oscillator nearby. No, it was not connected to the oscillator...
The difficult we do today; the impossible takes a little longer.
 

Offline SantaClaw

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Re: Inside the new Korad KA3305P linear PSU
« Reply #77 on: December 02, 2015, 04:00:42 pm »
I think I'll order myself one of these.. comes to 355$ incl shipping & tax though.....
 

Offline torch

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Re: Inside the new Korad KA3305P linear PSU
« Reply #78 on: December 02, 2015, 04:50:31 pm »
What part of the world are you in?

Hmmm. Doing the math, you could be in Canada and talking CDN$, since the loony has sunk so low recently.
 

Offline SantaClaw

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Re: Inside the new Korad KA3305P linear PSU
« Reply #79 on: December 02, 2015, 10:27:34 pm »
Norway, The very north of it too, 69.7269° N, 30.0456° E :D
 

Offline pascal_sweden

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Re: Inside the new Korad KA3305P linear PSU
« Reply #80 on: December 02, 2015, 10:50:41 pm »
I was looking at the Korad website, and they seem to have many different versions.

http://koradtechnology.com/en/Products.html

What is the difference between the KD series (Encoder-controlled and Digital Control DC Power Supply) and the KA series (Digital Control DC Power Supply)?

I am not refering to the D extension (non-programmable) and the P extension (programmable),
but really to the first two characters in the model names: KD or KA.
 

Offline SantaClaw

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Re: Inside the new Korad KA3305P linear PSU
« Reply #81 on: December 02, 2015, 10:53:32 pm »
http://www.ebay.com/itm/KORAD-KA3005P-Programmable-Precision-Variable-Adjustable-30V-5A-DC-Linear-Po-/111455671404?hash=item19f346946c

http://www.ebay.com/itm/KORAD-KD3005P-Programmable-Precision-Variable-Adjustable-30V-5A-DC-Linear-Po-/131367286456?hash=item1e9619b6b8

Easier to compare ^^

Looks like it's missing the memory features, and it's got a completely different interface just two encoder wheels in stead of encoder wheel + buttons. Otherwise the specs look identical.

The KA series looks to be a bit more expensive.


User manual: http://www.sra-shops.com/docs/srasolder/instructions/ka3305_user_manual.pdf


I assume it handles 240v ? it says 220/230v, but that's usually +-10% right?

Ok, SRA-Shops comfirmed it. It works fine on 240v 50hz :)
« Last Edit: December 03, 2015, 01:24:15 am by SantaClaw »
 

Offline icpart

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Re: Inside the new Korad KA3305P linear PSU
« Reply #82 on: December 04, 2015, 08:30:16 am »
Very interesting power supply,
Seems is there also new modification of that PSU with remote sense option. You can see here on picture from Korad website:

Also from description:
Code: [Select]
The remote measurement terminal compensates the voltage drop of the wire Just look of these interesting new added screw terminals on back. 
Also there is modification of that PSU without binding posts maybe from Reichelt Germany :-//:

Also there is rebranded version under TENMA from Farnell under model number 72-2645:
http://uk.farnell.com/tenma/72-2645/power-supply-bench-0-30v-5v/dp/2478801
But on Farnell website I can't see any screw terminals on back for remote sensing from pictures. But from description in datasheet of 72-645:
Code: [Select]
Complete digital control / programmable
• 10mV / 1mA resolution
• Low noise and ripple
• CV / CC constant voltage and constant current modes
• 5 sets of parameters can be stored and recalled
• 100 sets of stored parameters inside for programmable recall
• The remote measurement terminal compensates the voltage drop of the wire
• Industrial grade, with load for a long time
• Interfaces USB and RS232

Also i tried to find any user manual of that new models but without success.
« Last Edit: December 04, 2015, 08:39:54 am by icpart »
 

Offline torch

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Re: Inside the new Korad KA3305P linear PSU
« Reply #83 on: December 04, 2015, 10:30:13 am »
I think I read somewhere that those recessed terminals are a European safety requirement. So you can't fry yourself if you accidentally come in contact with 30VDC. Perhaps the screw terminals on the rear are duplicates of the front panel outputs to make up for the lack of screw posts on the front?
 

Offline robert_

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Re: Inside the new Korad KA3305P linear PSU
« Reply #84 on: December 04, 2015, 11:01:10 am »
I think I read somewhere that those recessed terminals are a European safety requirement. So you can't fry yourself if you accidentally come in contact with 30VDC. Perhaps the screw terminals on the rear are duplicates of the front panel outputs to make up for the lack of screw posts on the front?
Its mostly to keep people from removing the shrouds from their test leads to fit the old-style connectors, and afterwards, have unsafe test leads. From practical experience, that happens all too often.
Actually i fit the safety terminals on everything i build, as i do lots of "high"voltage stuff and therefore, use insulated 4mm test leads almost exclusively. I dont remember having ever neded to directly connect bare wires to any piece of equipment (i DO understand the need to do so for highest precision measurements).
There are these extremely useful little things, quick connect 4mm plugs. Much easier to use, safe and easy to connect/disconnect...
 

Offline Electro Fan

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Re: Inside the new Korad KA3305P linear PSU
« Reply #85 on: December 04, 2015, 11:22:59 am »
A little bit off topic but it would be interesting to compare this vs. the Rigol PS. 

I have had a Korad single channel PS for a couple years or so and I think it is a very good power supply.  I'm a Korad fan (and a SRA Soldering fan - where I got the Korad) but for this price range it seems the two offer pretty different designs for a similar price. 

The newer Siglents look like a modern hybrid between the Korad and the Rigol; the Siglents might also be worthy of consideration.

For what it's worth I find the User Interface on the KA3005P to be very straight forward friendly with no muss or fuss - and it appears the KA3305P is pretty similar - which is a good thing.  On the other hand, all the bells and whistles on the Rigol are pretty interesting and when you clean up the "Hello Kitty" UI and put it into the Siglent UI the Siglent looks pretty good.  So for UI, the Siglent is pretty appealing (and the Rigol might be A-OK too - lots of happy users around here), and the Korad is sort of conventional but highly useable.... so it might come down to UI preference, and how well they each perform (in terms of accuracy, stability, etc).
« Last Edit: December 04, 2015, 11:38:13 am by Electro Fan »
 

Offline SantaClaw

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Re: Inside the new Korad KA3305P linear PSU
« Reply #86 on: December 08, 2015, 04:49:12 am »
And now, I've ordered one :)
 

Offline TopLoser

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Re: Inside the new Korad KA3305P linear PSU
« Reply #87 on: December 08, 2015, 05:11:45 am »
And now, I've ordered one :)

Insides look very similar to what's in these:

http://uk.farnell.com/tenma/72-10505/power-supply-3ch-30v-3a-adjustable/dp/2251949

They just merged the two identical sets of boards in the Tenma unit into 2 larger boards and put a new front panel on it.

I'm selling the above Tenma supplies for £50 plus £20 European shipping, they don't have the RS232/USB interface though.
 

Offline SantaClaw

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Re: Inside the new Korad KA3305P linear PSU
« Reply #88 on: December 08, 2015, 06:16:51 am »
That thing is only 3a
 

Offline TopLoser

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Re: Inside the new Korad KA3305P linear PSU
« Reply #89 on: December 08, 2015, 06:24:08 am »
That thing is only 3a

'That thing', I like that description of them!
 

Offline pascal_sweden

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Re: Inside the new Korad KA3305P linear PSU
« Reply #90 on: December 08, 2015, 06:28:38 am »
Is it better than or similar to the Siglent SPD3303X power supply?
 

Offline dom0

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Re: Inside the new Korad KA3305P linear PSU
« Reply #91 on: December 08, 2015, 06:54:40 am »
I think I read somewhere that those recessed terminals are a European safety requirement. So you can't fry yourself if you accidentally come in contact with 30VDC. Perhaps the screw terminals on the rear are duplicates of the front panel outputs to make up for the lack of screw posts on the front?

No and no. Most likely the rear screw strip is for the added sense lines, since I can't see anything like sense contacts on the front panel.

The product image above looks shopped anyway. The angle of the shrouds inside the 4 mm sockets doesn't match the angle of the front panel.
,
 

Offline SantaClaw

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Re: Inside the new Korad KA3305P linear PSU
« Reply #92 on: December 09, 2015, 05:03:51 am »
Insides look very similar to what's in these:


http://uk.farnell.com/tenma/72-10505/power-supply-3ch-30v-3a-adjustable/dp/2251949

Control board looks nothing like it:

Korad:



vs

Tenma:



vs

Korad:



The Tenma looks to be an older design, as it's very similar to what was tested here (2012):



Otherwise it's not programmable, only 3a per channel, for a total of 6a max in series, I need at least 5a per channel for my usage. Thanx for the offer, but no thanx, it's not what I'm after.
 

Offline torch

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Re: Inside the new Korad KA3305P linear PSU
« Reply #93 on: December 09, 2015, 06:00:37 am »
'That thing', I like that description of them!

So give us a better one. 

I can appreciate that you might not have enough margin at that price to send one "down under" to a man who makes room on his bench by throwing $10,000 scopes to the floor, but as a vendor, you must have one around that you could open up and demonstrate to us. You know what we want: pros, cons, specs, real world tests and lots of pictures.

Who knows? Maybe you'll attract the interest of someone who wants a bench supply but doesn't need 5 amps per channel or a programmable interface.
 

Offline TopLoser

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Re: Inside the new Korad KA3305P linear PSU
« Reply #94 on: December 09, 2015, 06:31:14 am »
'That thing', I like that description of them!

So give us a better one. 

I can appreciate that you might not have enough margin at that price to send one "down under" to a man who makes room on his bench by throwing $10,000 scopes to the floor, but as a vendor, you must have one around that you could open up and demonstrate to us. You know what we want: pros, cons, specs, real world tests and lots of pictures.

Who knows? Maybe you'll attract the interest of someone who wants a bench supply but doesn't need 5 amps per channel or a programmable interface.

See the teardown above, that's exactly what the Tenma ones are. The dual channel ones are just two identical sets of boards in one case.
 

Offline SantaClaw

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Re: Inside the new Korad KA3305P linear PSU
« Reply #95 on: December 09, 2015, 06:09:08 pm »
I wonder if I get the "new" version with the EU style banana terminals on the front... I did ask the seller if it came with the updated firmware for the M4 memory button issue, and they replied that all their stock had this update.
 

Offline SantaClaw

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Re: Inside the new Korad KA3305P linear PSU
« Reply #96 on: December 09, 2015, 06:10:56 pm »
See the teardown above, that's exactly what the Tenma ones are. The dual channel ones are just two identical sets of boards in one case.

1 question though, I see that the Tenma does NOT come with a 110v/220v selector switch, what is it's voltage range ?
 

Offline TopLoser

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Re: Inside the new Korad KA3305P linear PSU
« Reply #97 on: December 09, 2015, 06:22:27 pm »
See the teardown above, that's exactly what the Tenma ones are. The dual channel ones are just two identical sets of boards in one case.

1 question though, I see that the Tenma does NOT come with a 110v/220v selector switch, what is it's voltage range ?

Google says 207v-253v
 

Offline torch

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Re: Inside the new Korad KA3305P linear PSU
« Reply #98 on: December 09, 2015, 07:06:08 pm »
Is it better than or similar to the Siglent SPD3303X power supply?

Based on recent Siglent business practices, I'd say anything is better than theirs.
 

Offline SantaClaw

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Re: Inside the new Korad KA3305P linear PSU
« Reply #99 on: December 18, 2015, 02:47:23 am »
Well, It arrived today! Considering the shipping costs, I suppose I shouldn't really be surprised. Looks identical with the one torch got.
Fired it up, not forgetting to  swap over the 220/110V switch, it seems to be working just fine.
Came with TWO sets of banana/alligator leads, extremely slippery silicone/plastic protector on the alligator clips.

So, how do I feel it works? Well, it's down to what I have to measure it with.
lol, I've got a Uni-T (yeah, you can all stop laughing now.) UT81C scope meter, the top of the range scope meter from Uni-T.

According to it, (yes, I AM going to buy me a fluke 87, stop bugging me about the Uni-T)  it's as following:

Indicated: 5.00V on the psu, measured: 4.99-5.00V
Indicated: 31.00V on the psu, measured: 31.03V

Indicated: 0.01v on the psu, measured: 12.4mV(without REL 400mV range)  [0.012V 4V range]
Indicated: 0.01v on the psu, measured: 71.9mV [with REL 400mV range] [0.072V 4V range]

^So, that's why I don't really trust it all that much, and it IS a Uni-T lol^

How bout current?

Well, I hooked up an 56ohm (5%) resistor, because I had one.. lol

4V 0.5A current limit: Blew 500mA fuse on multi-meter... lol

Tried again: 4V 0.5A current limit, this time, on the A range on the multi-meter... lol
Indicated 4V, 0.066A on the psu, measured 0.071A on the meter 4A range.

5V 0.5A current limit:
Indicated 5V 0.084A Measured 0.089A 4a range.

Resistor is heating up :)

5.5V 0.5a current limit:
Indicated 5.50V 0.092A Measured 0.098A 4a range.

6V 0.5A current limit:
Indicated 6V 0.102A Measured 0.107A

Btw, Meter is indicating 0.000A when psu output is off.

I also shorted it out @ 31V 5.1A, and 0.001V 5.1A both channels no problems at all, fan spun up loud.

The only issue I have met, is that one time I powered it on, it turned on with the output on !!
I think it was because of the settings in the software? I've been unable to replicate it.

I set all the M buttons to 0.00V and 0.00A to be on the safe side. In case I hit one accidentally.. lol

So, the USB interface is working fine. Below is both the PSU interface(on the right) and the Meter interface (on the left)
As you can see, it's indicating 6V 0.102A on the psu, and 0.107A on the meter.



Note, update rate on the PSU is much higher then the gif will allow, similarly the update rate on the meter is set to 1sec, but you can get "instant" updating by disabling it.
Alos, the most noisy thing is the regulators for the fan, they keep buzzing, changing with the pitch of the fan...
« Last Edit: December 18, 2015, 06:25:54 am by SantaClaw »
 


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