EVENTEK Lab Power supply faulty - Page 1
Forum section: electronics / testgear

author: carlonb
author_rank: Contributor
timestamp: March 15, 2025, 10:36:49 pm
content: Hello everyone,I have a lab power supply type EVENTEK KPS3010D that has always worked well, 0..30V 10A max purchased in 2022.Today, powering a load of a few mA at 5V, after a few minutes it turned off completely.I checked the fuse, but it was OK.I turned it off for a few seconds, then turned it back on, it always worked for a few seconds then it turned off in fault again.When I say "turned off" I mean that the V and A displays and the green LED of voltage present are off and obviously there is no voltageon the load.I noted that during the few seconds that it is working, all the voltage and max current adjustments work correctly, then everything suddenly turns off.Checking the board in detail I don't notice anything burnt or disconnected.I attach some photos, unfortunately I looked for the wiring diagrams but I found nothing, I ask if anyone has had the same typeof failure and if are able to direct me to attempt a repair.I have multimeter and o'scope to be able to take measurements.Thanks in advanceCarlo

author: carlonb
author_rank: Contributor
timestamp: March 26, 2025, 03:03:53 pm
content: Please, no one can help?

author: tunk
author_rank: Super Contributor
timestamp: March 26, 2025, 03:38:17 pm
content: Most likely it's a rebadged version - are thereany markings or model numbers on the PCBs?

author: temperance
author_rank: Super Contributor
timestamp: March 26, 2025, 03:45:35 pm
content: It seems you are the only one with this problem and power supply.QuoteFrom your description it looks like the power supply for the control boards is shutting down.YT has this one:Unlike yours It said poof. But the part broken is supplying the control board.Be careful if you are inexperienced working on mains voltage powered circuits.

author: carlonb
author_rank: Contributor
timestamp: March 26, 2025, 06:17:41 pm
content: Quote from: temperance on March 26, 2025, 03:45:35 pmHi temperance, thank for the reply.Do you mean that also mine has the TNY277 faulty?Ok, about mains circuits I'm experienced... so I can go on and try..

author: Microcheap
author_rank: Frequent Contributor
timestamp: March 26, 2025, 08:40:14 pm
content: These power supplies are sold under various brands Wanptek, Kuaiqu, Nice-power, iFix.... and many many others, and there's a huge number of models with different front panel but same main board, probably all made in the same factory.Newer models have revised boards with some components changes but basically the same circuit. I have fixed many of them and still have some left in my shop, they work fine for the price and when they fail, it's relatively easy to repair.Anyway, the symptoms you described looks like the problem is just the filter capacitors. Zooming in your picture I think I can see the leaked electrolyte under the caps. It's a very common fault.Check the capacitors first, then the 2 MOSFETs and the Schottky diode on the heat sink and then the TNY277, although when those fail the input fuse normally also blows. And since you are there, check the NTC thermistor on the input, it should read close to 5 ohms.

author: carlonb
author_rank: Contributor
timestamp: March 26, 2025, 10:18:05 pm
content: Thanks microcheap,I will check these capacitors if there are leakages and then I will replace them.I will check also the NTC.

author: carlonb
author_rank: Contributor
timestamp: March 29, 2025, 08:45:07 pm
content: Quote from: Microcheap on March 26, 2025, 08:40:14 pmI removed the two 470uF 250V capacitors and as you noticed they do have electrolyte leakage.I then checked their capacitance with my DMM, one measures 417uF, the other 440uF.I cleaned the PCB of electrolyte residue and ordered two new ones.I checked NCT and it measures about 6 Ohms.

author: carlonb
author_rank: Contributor
timestamp: May 01, 2025, 06:11:59 pm
content: Hi all, good news!Today I replaced the two 470uF 250V capacitors but the fault was not resolved.Then I replaced the TNY277G, struggling a bit due to the limited space, but in the end it solved the problem.It has been working for a couple of hours with a load of 12V 1.8A and it no longer blocks as it used to after a few minutes or seconds of operation.Byecarlo