OWON P4305 Lab Power Supply Review (1): First Tests, Failure & Teardown

[@mateoferrer]

Hi Robert. Honestly, I am impressed with your review of the Owon power supply. I've reviewed your 7 videos (Even Mission Impossible doesn't have that many chapters) and it's amazing that so many conclusions can be reached with a power supply, an oscilloscope, 5 halogen lamps and a 0.1 Ohm resistor! Your method of review should become a standard. My congratulations Robert!!. The way you have to check the constant current mode in a power supply is amazing and it is irrefutable. You are my new idol!! Thanks.

[@robertssmorgasbord]

Hello Mateo. First, thank you very much for the praise! I'm blushing here 🙂 Usually I get a review done in two (lengthy) parts. However, due to that intermitted failure I made far more videos about that lab PSU than I ever intended to do 🙂 And of course, you're very welcome!

[@harrystopic2112]

Hi Robert, I don't think the Owon is as bad as you make it out to be. Please consider the following ... The extreme voltage curve (16:37 >>>) when switching on the PSU / self-made load is due to the very high inrush current of the halogen lamps. The halogen lamps only have a reasonably stable power consumption after they have reached operating temperature. All in all i like your videos and even if not everything is perfect there is at least reason to discuss about them. Best regards..... Harry 0815

[@robertssmorgasbord]

Hi Harry, you're absolutely right about the high inrush current of halogen lamps. Wolfram/Tungsten has a (linear) temperature coefficient of 0.00411/K. So if the filament is heated up from 0°C to the usual 2700°C the resistance increases by a factor of 11. Or the other way around: The "cold" resistance is less than a tenth of the "hot" resistance. However, if I would have connected a reasonably temperature stable resistor as a load with the same resistance as the cold halogen lamps (about 2.5Ohm), don't you think the OWON would have overshot too? Anyway, your comment is going to my wall of video ideas and I'll test that at some point in the future ;-) Best Regards Robert

[@harrystopic2112]

@@robertssmorgasbord Hi Robert, thank you very much for your answer. An overshoot is to be expected, as the power supply tries to build up the set voltage first and then to switch to the CC mode. You can follow this very nicely with your measurements with the OWON. First the CV mode is active for a short time and then the power supply changes to the CC mode. In my humble opinion, the speed of regulation until the operating current is reached is an important quality criterion. But of course also the peak voltage that is reached. Just test with an load resistor. A resistor of 1-5 ohm / 5-10W should be sufficient, as the measurements only take 1-2 seconds. And please limit the taget voltage during the test near to the operating voltage, otherwise there will definitely be an overshoot, as the setpoint voltage is applied to the output capacitor and the difference is noticeable as an overshoot. You should be able to measure the capacitance at the output sockets ...... www.emsit.sk/SharedContent/EEVblog/Owon_P4603/15.jpg. I'm looking forward to the result ... You probably too ... 😉 Greetings from Fröndenberg

[@robertssmorgasbord]

@@harrystopic2112 Hi Harry, thanks for your insight! I'll definitely do more tests regarding the overshoot. And because I'm really curious about the outcome now 😉, I'll try to do it over the next weekend So the video might be published on October the 2nd. Greetings from Stuttgart

[@robertssmorgasbord]

@@harrystopic2112 OK, I've done the measurements and the video is published: OWON P4305 Lab Power Supply Review (7): Switch On Transients Revisited kzbin.info/www/bejne/hp7UZHuubrtpeZI

[@wi_zeus6798]

Seems like they have magnetically shorted the main transformer with the screw and the metal case parts... Or is it a plastic screw?

[@robertssmorgasbord]

I think its a big old black nylon bolt going through the center of the core. But I have to admit I didn't check that. Now I have to open the thing up again! See what you make me do ;-)

[@wi_zeus6798]

@@robertssmorgasbord :D

[@Debraj1978]

First time have seen a torrid transformer. Not sure of any advantage though of that.

[@robertssmorgasbord]

They are more efficient (thus smaller for the same power rating) and have less stray magnetic fields (that's one reason why they're more efficient) than conventional transformers.

[@PeterMilanovski]

At least it was putting out 5A at 24V, my eBay special is rated for 30V 10A but not at the same time LoL.. it just doesn't want to put out 30V at 10A, must be the limitations of the switching power supply....

[@robertssmorgasbord]

Well, I had little to no doubts that the P4305 (OWON wanting to be a 1st tier Chinese vendor like RIGOL) would at least meet the specs (30V/5A/150W). So far (the display trouble aside) I'm only disappointed with the switch on transients and the fan noise.

[@PeterMilanovski]

@@robertssmorgasbord that is a real shame, it looks very promising with a display that gives just enough information, a linear power supply and the ability to actually deliver 150. If the transient problem can be fixed and the issue with the screen solved, then this could be a great power supply! Although.... I have since learned that 60V or higher is better and 10A or higher is also better. I only work with audio related electronics and I thought that 30V should be plenty until I wanted to check capacitor DC leakage! I realized that I'm limited up to 30V capacitors if I want or need to test them at their full rated voltage... I have to use a DC to DC boost converter for higher voltages but it adds complexity, a simple single high voltage power supply at a cheap price would be great just for that reason alone....

[@robertssmorgasbord]

@@PeterMilanovski Yes, it does look very promising - that's the reason I bought it in the first place. Reading through your comment I remembered that OWON makes another version of that power supply, the P4603 (60V/3A/180W). Of course 3A/180W might not be enough for testing audio power amplifiers. I guess for something with 60V/10A/600W you'll have to pay quite a lot. E.g. B+K Precision BK9205 60V/25A/600W 20mVpp ripple/noise - about 800€ :-(

[@PeterMilanovski]

@@robertssmorgasbord 60V 3A is good enough for testing capacitor purposes, with an analogue amp meter in series, you can test capacitors up to 60V for DC leakage current, anything over and above 60V a DC to DC boost converter would be needed unless you have a power supply that can go way above 60V. Or another method would be to use a transformer that you have wound your own secondary for higher voltage output or get one out of one of those mosquito zappers with the ultraviolet light inside, I have found one that someone threw out, at the time, I didn't know what I was going to do with it but I grabbed it anyway, as it turned out it had an EI core transformer with 1kv secondary output! If I use it with a Variac Autotransformer, I can regulate the output after fitting and bridge rectifier... It's all about testing those capacitors LoL... They are amazing things but cause so much problems... I like those old American capacitor testers because they can test up to 600V but getting one shipped to Australia, well by the time you include shipping which cost more than the unit itself and then there's import charges... It's way too expensive so I have no choice but to think up a different way to do it, it's not elegant but if it works.....

[@robertssmorgasbord]

@@PeterMilanovski I do understand your problem. With the decline of vacuum tube electronics high voltage capacitor tester are no longer in demand and thus became some expensive specialized kind of kit. Your idea of using a variac with a modified transformer is great. I guess for just testing capacitor leakage your requirements regarding ripple and noise are not that high. So this seems to be a good solution.

[@andymouse]

Intermittent faults ...ya gotta love 'em ! That's a shame but the supply dosent do well in the comments below but I think you get quite a bit for 175 quid ....just sayin...cheers

[@robertssmorgasbord]

Yeah, I'm currently filming a short addendum testing for that fault - so I can get at least another video out that unit :-) And yes, you're kinda right. Less than 4mVpp/1mVrms noise/ripple is quite OK for less than 200€. But I'm still disappointed about those output switch-on transients.

[@andymouse]

@@robertssmorgasbord Agreed but would like to see it against some other supply in the price range...willing to bet it can fight its corner !...cheers.

[@robertssmorgasbord]

@@andymouse Unfortunately I know of nothing else in that price range. The KORAD KA3005D is a little less than 100€, the Siglent SPD1305X is just below 300€ (sports remote sensing!) and the RIGOL DP711 is about 350€. But yes, I would love to test these (or see a detailed test of those), just to see what you lose/gain for +/-100€. However, currently I won't spend another few hundred bucks on lab power supplies just for the fun :-)

[@andymouse]

@@robertssmorgasbord No, don't expect you too ! but my gut tells me this isn't a bad deal I look forward to more of you review and we will see...cheers.

[@robertssmorgasbord]

@@andymouse But I would like to ;-) And at some point I might :-) Anyway, the display is gone now for good. I tried to recreate the display problem - unsuccessfully (upcoming 2nd part - me torturing the unit). So I set everything up to continue with the review - and the display was dead. I'm really paranoid about the whole thing now. It still sits on my bench and each time I walk by I switch it on to see if the display is working again :-)) So it might be a while until I can finish the review.

[@GEORGE-jf2vz]

Too many problems for the price. Really any price.

[@robertssmorgasbord]

I'm admittedly quite disappointed with the unit at this point. However, I will not pass judgement here until somebody (or me) does the same tests with a sub $100 lab power supply (e.g. KORAD K3005D) and a +$300 one (e.g. RIGOL DP711).

[@johngabris9690]

your effing hand is in the way

[@robertssmorgasbord]

Sorry about that 🙁

[@robertssmorgasbord]

@Matthew Khari I don't know either (if anyone cares) 😉 But since the InstaPortal scam website is already down (Instaportal Scam Instagram Account Hacker: www.onlinethreatalerts.com/article/2021/3/13/instaportal-scam-instagram-account-hacker/ ) I don't care to remove your comment 🤣

[@robertssmorgasbord]

@Kamala Tay Yeah, right! Are you for real? This is a technical channel and my esteemed viewers are far too smart to fall for such a scam.