EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: edoelas on November 18, 2023, 10:56:16 am
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I needed to buy a PSU and after reading some threads and watching some videos I decided on a Korad KA3005D. The first thing I tried was testing it with my not-so-trusty multimeter. I was getting 0 volts and the OCP was turning off the PSU. Turns out I was using the wrong terminal in my multimeter. After switching to the right terminal I could read the voltage properly. I am explaining all of these because while I was trying to figure out what was wrong with my unit I found this video: https://www.youtube.com/watch?v=MQD0zeX7LjI] [url]https://www.youtube.com/watch?v=MQD0zeX7LjI (http://[url)[/url]
I used the automatic translation feature on YouTube and what I could understand is that if your display has a pinkish tone while is turned off, it can be fake. I bought my unit from this aliexpress shop: https://es.aliexpress.com/item/1556945117.html?srcSns=sns_Copy&spreadType=socialShare&bizType=ProductDetail&social_params=60424466161&aff_fcid=468eae4fcafd4dc5b84ec121e0174bad-1700304672819-02675-_EHi63sD&tt=MG&aff_fsk=_EHi63sD&aff_platform=default&sk=_EHi63sD&aff_trace_key=468eae4fcafd4dc5b84ec121e0174bad-1700304672819-02675-_EHi63sD&shareId=60424466161&businessType=ProductDetail&platform=AE&terminal_id=1464d76c8282409c990fbddd70a5a408&afSmartRedirect=y (https://es.aliexpress.com/item/1556945117.html?srcSns=sns_Copy&spreadType=socialShare&bizType=ProductDetail&social_params=60424466161&aff_fcid=468eae4fcafd4dc5b84ec121e0174bad-1700304672819-02675-_EHi63sD&tt=MG&aff_fsk=_EHi63sD&aff_platform=default&sk=_EHi63sD&aff_trace_key=468eae4fcafd4dc5b84ec121e0174bad-1700304672819-02675-_EHi63sD&shareId=60424466161&businessType=ProductDetail&platform=AE&terminal_id=1464d76c8282409c990fbddd70a5a408&afSmartRedirect=y)
I am worried that I just bought a 100 euro fake PSU that, while outputs the right voltage, it may produce more noise or not be as good as it should be. I do not have an oscilloscope to test it. What do you think? Is there another way to check if it is real? (like looking at the serial numbers of the components or something like that)
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I think if it works ok, then nothing to complain :)
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I agree, but the problem is that I am not sure if it works okay. Right now I do not own an oscilloscope so I am not planning to make any delicate measurements, but in the future, I will.
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I think if they using the same circuit, it should works almost the same. Show the photo what is inside.
If you have DMM you can check if it produce proper voltage output. Don't be picky about accuracy, because you can calibrate KA3005.
Add some load to get 4-5 Amps current (you can check it on PSU display) and check output voltage with DMM, but note - you're needs to measure voltage directly on PSU terminals, not after wires to the load, because voltage will be reduced due to resistance of wires and high current
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The things he talks about in that video are similar to the things you will see vary from batch to batch in many products. Sometimes they've made improvements, and sometimes they've had to adapt to changing parts from suppliers. This is especially true if they make new batches infrequently. This happens a lot in China. A company might get a batch made over a day or two, and another batch made months later, when the supplies of parts have changed. They might not even get the second batch make in the same shop that assembled the first batch, leading to some variation in PCB appearance, the way a display window looks, paint finish, or the nuts and bolts used. If something is a complete piece of garbage its easy to tell its fake. If its pretty close to the original it might be another batch, or something they changed to improve things. Few manufacturers do much to stamp their indelible mark on a product. I'm sure they'd like to, but to do it effectively is not easy.
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Don't know anything about fake Korad but saying if it works, then it's OK is totally dumb. Besides actually meeting the specs, you don't even know if it's electrically safe. I've seen poorly wound transformers where secondary winding touches primary. And it wasn't some wire with reinforced insulation, just usual enameled magnet wire.
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Also why in hell did you even order it from Aliexpress? For example you could buy in from reputable dealer for EUR 105 delivered to Spain https://www.reichelt.com/es/en/laboratory-power-supply-unit-0-30-v-0-5-a-stabilized-ka3005d-p135688.html?&nbc=1 (https://www.reichelt.com/es/en/laboratory-power-supply-unit-0-30-v-0-5-a-stabilized-ka3005d-p135688.html?&nbc=1) And most likely there are cheaper places.