KORAD KA3005D Mini Review and Problem.

[cybertronicify]

Heres a mini review of this Power Supply.

Power supply has the following taps:

0-7v
8-14v
15-21v
22-31v

The goods:

1 ) Disables the output when you press any "Memory" button. i.e M1, M2, M3 etc
    *To get into M5, Press the M4 button and turn the "ADJUST" knob right. Funky huh?
2 ) OCP OVP Can be set to protect your board incase the power supply goes boom.
    * To set OCP OVP just set your voltage and current. With output off press the OCP and/or OVP button(s) to turn them on.
3 ) The BEEP is still makes a dying bird sounds and can be turned off by holding the OCP button until it makes a BEEEEP sound.
4 ) The output will refuse to turn on if the voltage or current is set above the stored OCP OVP voltages and current. (very handy)
5 ) Store up to 5* Memory Voltage and Current settings.
    *The fifth one is annoying to get to.
6 ) Big beefy* mains power button that actually switches the mains primary.
    *Looks not rated for 3 amps, but it works and its still working.
7 ) CHEAP very CHEAP (as in priced low, build quality not bad.) Got mines for $50 USD NEW shipped.
8 ) You can lock all soft buttons on the keyboard with the LOCK button.
9 ) Theres a thermistor on the series pass transistor heatsink. I presume it will turn the unit off if it goes over temp?

And the Bads:

1) LOUD FAN. Korad, you don't need the fan to be spinning at 3000 rpm idle. Full load sounds like a jet engine. (At least it uses a standard 2 pin 12v 80mm fan. Just replace it.)
2) Very confusing users manual, no where does it say how to set a OCP OVP.
3) Makes a BOING sounds when turning on by the Mains power button.
4) The transformer is very hot, you will need to mess with the airflow a bit to get air to pass next to the transformer. (on Daves unit, it has a piece of steel bent down to force air pass the transformer.
5) Non switchable transformer primary, mines seems to be stuck on 220v. (SRA-SOLDER sells a switchable 110-220v one, not sure if this is a different generation)
6) Fan is controlled by current output not temperature. It has a thermistor, why not use it?
7) When on M4. Any movement on the "ADJUST" knob will move it to M5 and switch the output off. VERY annoying

The voltages and current readings are nearly spot on. The binding posts feels very solid. Does get a little hot to the touch on the rear of the unit but not burning.

Check out the pictures. Can someone tell if those Rubycons are real? The print on them looks high quality, they are quite cold (114F) after operating at high loads for a period of time.

FAKE RUBYCON CAPS. Expected....

------Original Post------

Hey everyone!

I just purchased a Korad KA3005D here in china for $50USD NEW, but all they had was 220v 50hz. I have a 110v to 220v transformer at home

http://www.ebay.com/itm/Goldsource-STU-300-W-Watt-Step-Up-Down-110V-220V-Voltage-Converter-Transformer-/160733095687?pt=BI_Circuit_Breakers_Transformers&hash=item256c706707

and i was wondering if the 60Hz of the 110v mains will interfere with the normal operation of the 220v 50Hz input of the power supply. Is this whole setup correct?

And how should i fully test a new lab power supply?


Jason

[Artraze]

A quick look at the Korad KA3005D specs shows:

Code: [Select]

Input voltage:110V +/-10% switchable to 220V +/-10%
Frequency range: 50- 60Hz

So not only should it be okay to run off 60Hz, but you should be able to switch it to run off 110V directly.

[cybertronicify]

Thanks for the info but i think i have the AU version. Theres no selector, not even under the stickers. The 50 Hz 60 Hz shouldn't matter right? It all goes into a bridge rectifier and boom DC out.

[nanofrog]

Thanks for the info but i think i have the AU version. Theres no selector, not even under the stickers. The 50 Hz 60 Hz shouldn't matter right? It all goes into a bridge rectifier and boom DC out.

Frequency won't be an issue.

Open it up and have a look at the transformer, as you *could* luck up and it have dual primary windings for series/parallel configurations.  Either way, since you have the step-up transformer, you'll be able to use it. 

[staxquad]

Your Korad KA3005D requires a 3A input fuse at 250v which would make that Goldsource STU 300 W Watt Step Up Down 110V 220V Voltage Converter Transformer underpowered and inadequate.  You need at least double the wattage.

[IanB]

Your Korad KA3005D requires a 3A input fuse at 250v which would make that Goldsource STU 300 W Watt Step Up Down 110V 220V Voltage Converter Transformer underpowered and inadequate.  You need at least double the wattage.

I rather doubt that power supply is going to draw 750 W from the mains?

[staxquad]

Your Korad KA3005D requires a 3A input fuse at 250v which would make that Goldsource STU 300 W Watt Step Up Down 110V 220V Voltage Converter Transformer underpowered and inadequate.  You need at least double the wattage.

I rather doubt that power supply is going to draw 750 W from the mains?

I would imagine that half the fuse rating is much too under, that Goldsource is going to blow it's fuse before the Korad goes full power.

Find out what the maximum input wattage rating for the Korad is, then get a voltage converter with enough wattage headroom.

Edit:
Did a test on my linear power supply.  At 30V 5A it consumes 262 Watts.  To get to 300 Watts input, it needs to go to 41V 5.12A.  So with my power supply, limiting it to 150 Watts output, that 300 Watt voltage converter would be sufficient.   The line fuse for the 40V 10A power supply is 6A for 208-230V and 10A for 115V.  At full power 40V 10A DC 400 Watts, it consumes 582 Watts input.  The Power Factor on that power supply is .38, the reason for the high current fuse on the input watts.

On another power supply, a hybrid switch mode, it requires 227 Watts input to reach 30V 5A.  It specifies "Maximum AC Input Power 625 VA" and "Maximum Input Current at nominal power line impedances 6A maximum" for it's rating output rating of 60V 5A DC while the Power Factor was .58 when I tested it at 30V 5A.

(I used low ohm high current variable rheostats for the loads.)

[cybertronicify]

If the Korad has dual primary i can just cut one and use only one? or parallel them up? The Korad is rated for 150W out so that is about 200W in. Its quite a hassle to carry around 300w step up, not to mention the 750w one. I will try to take it apart and see if its 2 primary windings.

[cybertronicify]

Before i open it up, i think i should fully test the supply as it is fairly new and i still have 10 more days to return it. How do i fully test this linear supply? I dont have a electronic load so that is not an option. I do have a 13.8v to mains inverter that i can try to load down the supply.

[nanofrog]

If the Korad has dual primary i can just cut one and use only one? or parallel them up? The Korad is rated for 150W out so that is about 200W in. Its quite a hassle to carry around 300w step up, not to mention the 750w one. I will try to take it apart and see if its 2 primary windings.

No, you don't just cut and leave not connected (aka NC). You'd wire them in parallel for 120V mains, and series for 230/240V (how it would currently be wired if it has a dual primary).

Understanding Transformers page might help.

[cybertronicify]

Oh ok cool, so ill just wire the 2 primary 110v in parallel and run it from there? I still need to test the supply first before i take it apart.

[nanofrog]

Oh ok cool, so ill just wire the 2 primary 110v in parallel and run it from there?

Assuming it actually does have a dual primary transformer, Yes. Just be careful of the current flow direction (+ to + & - to -).

They may have specified a single primary transformer (single input voltage) to cut costs, so you'll have to open it to find out.

[IanB]

Before i open it up, i think i should fully test the supply as it is fairly new and i still have 10 more days to return it. How do i fully test this linear supply? I dont have a electronic load so that is not an option. I do have a 13.8v to mains inverter that i can try to load down the supply.

Find some resistive loads to use, like car bulbs for instance. Test the supply by connecting a load and then using the voltage and current controls to check the regulation. Set the current to max and then wind up the voltage from zero. Use a multimeter to check that the voltage matches the displayed voltage. Use the current control to reduce the current. Check the supply goes into CC mode and reduces the voltage to regulate the current as you adjust it. Put a large load on the supply and leave it running continuously for several hours. Check that it remains stable, doesn't overheat and doesn't cut out.

[cybertronicify]

Ok, ill give it a 13.8v 5 amp 12 hour workout. So far its going perfectly, the voltages are spot on. Its a bit off on the amps like 0.05 amps off at worse.

[cybertronicify]

Okay it passed both tests. 13.8v at 4.8 amps for 12 hours. It also passed a 30 min short circuit full power.  But upon taking it apart, the transformer primary is sadly one coil. Theres no dual primary coils. There is enough room inside to add a 200w step up transformer but that will really obstruct the airflow as it is already in a very small form factor. Anyone else got an idea on a better way to "modify" this power supply to work on 110v?

[cybertronicify]

Heres a mini review of this Power Supply.

Power supply has the following taps:

0-7v
8-14v
15-21v
22-31v

The goods:

1 ) Disables the output when you press any "Memory" button. i.e M1, M2, M3 etc
    *To get into M5, Press and hold the M4 button and turn the "ADJUST" knob right. Funky huh?
2 ) OCP OVP Can be set to protect your board incase the power supply goes boom.
    * To set OCP OVP just set your voltage and current. With output off press the OCP and/or OVP button(s) to turn them on.
3 ) The BEEP is still makes a dying bird sounds and can be turned off by holding the OCP button until it makes a BEEEEP sound.
4 ) The output will refuse to turn on if the voltage or current is set above the stored OCP OVP voltages and current. (very handy)
5 ) Store up to 5* Memory Voltage and Current settings.
    *The fifth one is annoying to get to.
6 ) Big beefy* mains power button that actually switches the mains primary.
    *Looks not rated for 3 amps, but it works and its still working.
7 ) CHEAP very CHEAP (as in priced low, build quality not bad.) Got mines for $50 USD NEW shipped.
8 ) You can lock all soft buttons on the keyboard with the LOCK button.
9 ) Theres a thermistor on the series pass transistor heatsink. I presume it will turn the unit off if it goes over temp?

And the Bads:

1) LOUD FAN. Korad, you don't need the fan to be spinning at 3000 rpm idle. Full load sounds like a jet engine. (At least it uses a standard 2 pin 12v 80mm fan. Just replace it.)
2) Very confusing users manual, no where does it say how to set a OCP OVP.
3) Makes a BOING sounds when turning on by the Mains power button.
4) The transformer is very hot, you will need to mess with the airflow a bit to get air to pass next to the transformer. (on Daves unit, it has a piece of steel bent down to force air pass the transformer.
5) Non switchable transformer primary, mines seems to be stuck on 220v. (SRA-SOLDER sells a switchable 110-220v one, not sure if this is a different generation)
6) Fan is controlled by current output not temperature. It has a thermistor, why not use it?

The voltages and current readings are nearly spot on. The binding posts feels very solid. Does get a little hot to the touch on the rear of the unit but not burning.

Check out the pictures. Can someone tell if those Rubycons are real? The print on them looks high quality, they are quite cold (114F) after operating at high loads for a period of time.

FAKE RUBYCON CAPS. Expected....

[cybertronicify]

They glued the connectors down but not the 3 caps...

[cybertronicify]

Last 3.

[omgfire]

Can someone tell if those Rubycons are real?

Are they 105C rated? Rubycon USP was 85C rated and discontinued in 1999.
http://www.rubycon.co.jp/en/products/old_replace/index.html

[cybertronicify]

Yupp those are fakes. Thanks for the info. They are 105C rated haha.

[TomB19]

cybertronicify,

Did you find a source for a 110v transformer?  I sent an email to Korad a few days ago, requesting parts availability,  but there has been no response.  That's about as much support as I would expect from a Chinese manufacturer.

Does anyone know if the KD3005 has the same transformer?


- Tom