Author Topic: Inside the new Korad KA3305P linear PSU  (Read 59592 times)

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Offline YottaByte

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Re: Inside the new Korad KA3305P linear PSU
« Reply #125 on: June 06, 2016, 04:22:32 pm »
Opened it up and after finding no obvious loose connections, I re-seated every internal plug, which fixed the problem. Great PS at an even greater price!
 

Offline SantaClaw

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Re: Inside the new Korad KA3305P linear PSU
« Reply #126 on: June 06, 2016, 04:23:31 pm »
Excellent news, yeah, it's a good psu for the money :)
 

Offline YottaByte

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Re: Inside the new Korad KA3305P linear PSU
« Reply #127 on: June 06, 2016, 09:10:44 pm »
FWIW, I got this Korad KA3305D for $139 delivered from SRA Solder. Although they are sold as refurbished units, the one I got looked brand new and was shipped in the factory Korad box. The only difference being that the manual was a black and white printout of the factory manual. Hard to get anything close to this for that price, especially since I didn't need the Programmable model. So far I am extremely pleased with this unit.
 

Offline bitwelder

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Re: Inside the new Korad KA3305P linear PSU
« Reply #128 on: June 07, 2016, 05:41:29 am »
Gotta ask: is it possible to find anywhere the USB module used in the Korads, or are the schematics available?
I have a rebranded version of the Korad dual PSU that doesn't have the USB interface (but has the metalwork done to host it), so if possible it would be nice to 'mod' it.
 

Offline schuc

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Re: Inside the new Korad KA3305P linear PSU
« Reply #129 on: June 28, 2016, 11:41:30 pm »
GREAT info and thank you so much for this thread.

I am just getting into electronics and am trying to get a few necessary tools without breaking the bank as I am new and this will be at a hobby level.  I just got a Bryman multimeter and am looking at this power supply.  It was fun reading the past 6 pages of dialog on this and helps give me a feeling for what you have been experiencing.  It seems like a winner at this price range to me.

I'm interested in doing some Arduino and Raspberry Pi projects for various purposes(mostly sensor monitoring and graphing of collected data currently, etc).  I have a LOT to learn and need to get the basics down but it's going to be a fun ride.

Anyway, thank you for all the info related to this PSU.   :-+
 

Offline Scottjd

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Re: Inside the new Korad KA3305P linear PSU
« Reply #130 on: November 08, 2016, 07:01:56 am »
I decided to do a review on this unit. I know some bugs have been mentioned, this one I tested and reviewed is the latest with none of the bugs mentioned in this thread.
I also wanted to post the review since I know some people asked about a video.

TORCH: I hope you don't mind, I also put this thread in the description of my video for people that want to see detailed photos of the internals since you have posted such nice photos.

https://youtu.be/WRZY9mYmFBk
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Offline rsfoto

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Re: Inside the new Korad KA3305P linear PSU
« Reply #131 on: November 09, 2017, 11:05:41 pm »
Hi,

As I was in search of a PSU too and having read a lot I decided based on many of the opinions here to get a KORAD KA3305P power supply.

I got it yesterday and started to learn it.

OK with the unit there was a CD, a USB cable as well as 2 (two) yes 2(two) power cables with banana and crocodile clamps, but, yed but ... after seeing the images of the burnt PSU



and having seen in You tube the tear down of a similar unit by bigclivedotcom in which he analyzed the possible why of the fire



the first thing I did with the cables weas to inspect how the ends where mounted and ... SURPRISE ...

The same way as in bigclivedotcom video.

Well I am going to make a good connection by tinning the screwable end and soldering the cable to the crocodile.

I would like to thank all of you for those good messages which help a lot for taking decisions.

Attached some images of how I got the cables.

best regards Rainer
« Last Edit: November 09, 2017, 11:09:27 pm by rsfoto »
 

Offline Scottjd

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Re: Inside the new Korad KA3305P linear PSU
« Reply #132 on: November 10, 2017, 05:20:54 am »
Congrats on the new power supply. It’s not the burnt one, right? JK
I don’t remember if I mentioned this in the newer triple, but I know I do mention it in the first kora triple older one I reviewed to just ditch the cables. I think the other one I didn’t even mention them bakes it came with? But I dint really remember.
Depending on the power supply you have, you want the cables to be good quality with low resistance. You can even get nice ones without spending to much from Frankie over at 99centHobbies
http://stores.ebay.com/99centhobbies

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Offline rsfoto

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Re: Inside the new Korad KA3305P linear PSU
« Reply #133 on: November 10, 2017, 01:59:53 pm »
Congrats on the new power supply. It’s not the burnt one, right? JK
I don’t remember if I mentioned this in the newer triple, but I know I do mention it in the first kora triple older one I reviewed to just ditch the cables. I think the other one I didn’t even mention them bakes it came with? But I dint really remember.
Depending on the power supply you have, you want the cables to be good quality with low resistance. You can even get nice ones without spending to much from Frankie over at 99centHobbies
http://stores.ebay.com/99centhobbies

Hi Scott,

I got the KA3305P. Your review video was one of the main reasons I bought this brand.

Well as having read it comes with no cables I ordered some cables specifically the Brand Elenco and Type TL-16. Having seen the images on Amazon I thought they were good and OH what a deception. They are even stiffer then the ones supplied with the KORAD PSU. On the other side I also ordered some other cables from Elenco specifically the BNC cable type TL-3 as well as the TL-12 and surprisingly they are better then their own TL-16. The pair of Elenco TL-16 cost about US $ 8.00

I live in Mexico and it is even nowadays not so easy to find good stuff here. Unfortunately Mexican consumer wants everything cheap and the sellers adapt to it and if I shop in stores with good quality the stuff costs nearly double or triple the price somewhere else like in Europe or USA.

Already happened with a Arduino shield for a NANO. I plugged it into the power supply and PENG my NANO fried. Before that I had already contacted the Mexican seller to tell him that some soldered parts were all croocked on the PCB and his answer was ... Well you know you bought chinese and that is the quality I can sell. I ussed to sell better stuff but nobody bought it ... As you can see they do not know how to sell and go the easy way ...

So far at the moment my current requirements are not big so the cables more or less do work for me. Mainly Arduino projects but I was tired not being able to play with voltages and learn more about electronics.

Will keep searching for cables

What I found out is that if I have channel 1 voltage at 0.00 I can nor adjust channel 2 in any way. Getting the adjustment up to 0.01V in CH1 then I can adjust CH2 :-) I know it is nonsense not to have something adjusted but it happened by pure curiosity that I found it out. Same happens with the current adjustment. 

regards Rainer
 

Offline kelchm

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Re: Inside the new Korad KA3305P linear PSU
« Reply #134 on: January 16, 2018, 06:04:02 pm »
Can anyone share the dimensions of the KA3305P? It looks like the dimensions listed by SRA are incorrect.
 

Offline Scottjd

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Re: Inside the new Korad KA3305P linear PSU
« Reply #135 on: January 17, 2018, 06:02:43 pm »
Can anyone share the dimensions of the KA3305P? It looks like the dimensions listed by SRA are incorrect.
Measurement are just a tad bigger rounded off the actural size.
They include the feet, knobs, screw heads, handle on top, and front posts.
In my video, o don’t think I measured or considered the feet, or the handle on top.

Mine is a KA3305P, I don’t think the extra programming USB plug port makes a difference in this size. They all go into the same case, just an added whole for the USB and additional PCB board plugged into the unit inside the case.
Don’t forget to consider how far the plug sticks out the back when it’s plugged in, you can always buy a right angle plug also so it doesn’t stick out as far off a shelve.

I’m thinking this is what your looking for to make sure it will fit in the space you want it?
Scott
« Last Edit: January 17, 2018, 06:15:02 pm by Scottjd »
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Offline Scottjd

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Re: Inside the new Korad KA3305P linear PSU
« Reply #136 on: January 17, 2018, 06:36:31 pm »

What I found out is that if I have channel 1 voltage at 0.00 I can nor adjust channel 2 in any way. Getting the adjustment up to 0.01V in CH1 then I can adjust CH2 :-) I know it is nonsense not to have something adjusted but it happened by pure curiosity that I found it out. Same happens with the current adjustment. 

regards Rainer

Thinking back, I believe this is one of the bugs I reported to Korad.
The other gotcha I noticed on older manufactured units, is if you have the power enabled, turn off the unit, then turn it back on it will still have the power enabled.
UPDATE: Its been a while using this one since I own 3 different 3 channel PSU’s. But I just remembered on this newer model it wasn’t a bug. Channel 2 is the master by design. So if channel 2 it turned off all the way it cuts any power going to channel 1. I know this is sort of backwards, I would of rather they made channel 1mthe mater, but they didn’t.

Still I have 2 of these, the one older 3 channel and they are all still running as expected.
Note: I did have a fan go out on my older unit, well it didn’t stop all the way, just made some weird bearing noise sometimes when I turned it on. So I want to mention if you ever replace this fan on the older 3 channel units, it’s a 24V fan, not a 12V fan like a regular common computer fan.

So watch out for this, I thought the bug you mentioned was corrected the same time that the power staying on was corrected. It’s possable you might have bought old stock, or a refurbished old unit they sold to you?

The opinion on the power bug is mixed. Some people like this and consider it a feature because if the main power goes out when taking long time lapsed measurements on a project, then the unit continues to put power out to,the DUT when the mains power is restored. This only works of the logger is battery operated. I don’t know if a mains powered logger would continue taking measurements if the mains went out, this would depend on the logger unit and it features.

I reported this because I considered this a potential danger since the unit is capable of putting out 62VDC and 5 Amps, or 32VDC and 10 Amps, or 32VDC and 5 Amps depending if its running in serial or parallel mode, or how you have it wired at the time.

You might want to test this. Unfortunately it does not have the ability to update firmware, but was fixed and corrected with a firmware. You can contact Korad or your local supplier, sometimes they might be willing to just send a replacement board with the new firmware loaded on the chip. Its cheaper then shipping to them, but only request this, or attempt to replace the board if you feel comfortable wit something like this. It has a lot of capacitors and stored power that can be lethal or give you the shock of your life.
Scott
« Last Edit: January 17, 2018, 07:36:39 pm by Scottjd »
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Offline Candid

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Re: Inside the new Korad KA3305P linear PSU
« Reply #137 on: August 17, 2018, 11:26:10 pm »
Also, the most noisy thing is the regulators for the fan, they keep buzzing, changing with the pitch of the fan...

Mine don't buzz. Maybe yours has a bit of a gap between a heat sink and the board?

Well, they/it will start making a buzzing/grinding sound about 45 to 60 seconds after I turn it on, with no load.
I had the cover off, and it looks like it applies very low power to the fan at this stage, PWM? it doesn't spin on it's own, but starts if I give it a little help. The fan spins easily though, so it's working as it should, also it starts on it's own if I leave it alone long enough.
I got one of this PSUs from Welectron who stated to me that the units they sell are form latest 2018 charge. It does not have the M4 bug others I did not check up to now.

What I realized was that I hear a noise from the fan that did make me think that it is defect especially in low power. I checked it with direct voltage and the fan is ok. Then I checked the voltage the fan gets from the psu. Can someone check this with his unit? It is controlled with PWM. My fan runs all the time even without channels on. This "rippel" on the voltage is producing a little annoying sound. When the fan runs faster you can not really hear the ripple but when slow running it is a little disturbing and I wonder how long the fan will run with this special voltage it gets.
« Last Edit: October 06, 2018, 07:32:54 pm by Candid »
 

Offline spidola

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Re: Inside the new Korad KA3305P linear PSU
« Reply #138 on: August 18, 2018, 10:04:34 am »
This "rippel" on the voltage is producing a little annoying sound. When the fan runs faster you can not really hear the ripple but when slow running it is a little disturbing and I wonder how long the fan will run with this special voltage it gets.
What if you connect a capacitor in parallel to the fan's power pins?  ;)
 

Offline Candid

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Re: Inside the new Korad KA3305P linear PSU
« Reply #139 on: August 18, 2018, 03:35:29 pm »
That was my first thought and I think I will test it shortly.
 

Offline Scottjd

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Re: Inside the new Korad KA3305P linear PSU
« Reply #140 on: August 19, 2018, 10:49:57 am »
I have 2 of these, one has a low power and barely spinning fannthat turns in after it powers up about 1 minute(but output power is off).
The other, the fan stays off until I use the output and have a load on it, as it heats up the fan spins, depending on the temperature regulates how fast the fan spins. The difference between the units could be the locations of the sensor for the temp, or even how much thermal compound is applied?
Or maybe it’s a calibration thing, and at what room temp it was calibrated at?
It could also be some fans start to spin with less current then others, but both units might be putting out the same starting up current and voltage? Or one fan has slightly smother bearing then the other?

Yes, it is some PWN depending on the temp of the unit under load that speeds the fan up. I think the cap might give it that extra lush to keep it in a low spin on the cold start. But this might also depend on how stable the temp of room/house is?

I don’t recall seeing any variable resistor to adjust this for the fan.

I would try this with my units, but they are lacked and ready to move. Also even when I get my new place and the lab unpacked I might not have both of them anymore. I’m working with some local schools to give away some of the extra stuff I don’t need like 3 Korda PSU, and q Rigol DP832. I think I can afford to give up 2 of the Korads and put them to good use with the high schools engineering class or robotics club.
Also less stuff I need to move, or out in storage until I buy a new place.
Scott
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Offline willumpie82

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Re: Inside the new Korad KA3305P linear PSU
« Reply #141 on: October 28, 2018, 10:51:29 am »
I just received my Korad KA3305P (unfortunately received a Tenma rebrand with "safety" binding posts instead of screw terminals)
It seems that they still install the factory broken fans, although PWM controlled it makes an annoying rateling noise. Like it should I took it apart before turning it on, All the wiring was nicely tucked and secured but found the mains switch kinda loose (screws not completely fastened) I removed the handle to make it stack better with my other equipment, with it's 10ish kg it is not so portable after all.
« Last Edit: October 28, 2018, 10:54:17 am by willumpie82 »
 

Offline willumpie82

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Re: Inside the new Korad KA3305P linear PSU
« Reply #142 on: November 11, 2018, 12:01:30 pm »
I wanted to fix that fan buzzing, but apperantly it is not caused directly by the fan, the PWM control makes the fan hummm. I installed a new-ish fan and the problem retains. When I was at it I also took the effort of cleaning up the heat compound mess it came with.

there are ceramic isolators between the powertrannies and the heatsink, because of the fan retaining method used you have to disassemble the complete heatsink because a big cap is in the way of one of the screws. the fan itself has to be modified to fit in the slot of the heatsink.

below some pitures I took in the process
 

Offline Scottjd

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Re: Inside the new Korad KA3305P linear PSU
« Reply #143 on: November 11, 2018, 07:35:43 pm »
The only way to get the fan to stop under normal powered on and no load would be to use a fan that spends easier, and used less power. It’s the fan trying to spin at the minimum powers being delivered and not enough to get it started. Or maybe if the room was slightly colder with the ambient temperature it could be at a stop. When the fan stutters, if you spin it a little it will probably maintain a slow speed.
I didn’t realize you were going to replace the fan or I would have mentioned that before.

On some of the units you can adjust the output power of the contact on 5V rail in the back left (or right) corner with a variable resistor. You can measure the output from the posts with a load and inline meter, then turn it down a little if you dint use this 5 volt rail. Or maybe turn it down so you can still use it, but instead of it delivering 3 amps you might only get 2 Amps.
By turning this down it doesn’t work as hard or heat up as much with a 5 volt rail that is constantly on and not being used. This should allow the idle temperature to be lower, and as a result the thermal triggered fan PWN will put out less hopefully resulting in the fan not trying to start getting in the stutter.
So if you don’t use the 5 volt rail, this could be an option for you?
Hope this helps,
Scott
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Offline Pnoxi

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Re: Inside the new Korad KA3305P linear PSU
« Reply #144 on: March 14, 2019, 06:25:12 pm »
Power supply Tenma 72-2630 (Korad KA3303D ?) at a good price! 95.92€ + VAT

https://sk.farnell.com/tenma/72-2630/power-supply-bench-0-30v-5v/dp/2478798
 
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Offline SantaClaw

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Re: Inside the new Korad KA3305P linear PSU
« Reply #145 on: March 14, 2019, 06:44:01 pm »
Just want to mention, I've used my KA3305P for nearly 4 years now, It's been flawless for my usage.
 
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