Repair of Vevor Ultra Sonic Cleaner - Page 1
Forum section: electronics / repair

author: CaptainBucko
author_rank: Regular Contributor
timestamp: May 04, 2025, 10:02:05 am
content: I bought a Vevor Ultra Sonic cleaner which came as part of a wider deceased estate auction. It was broken and fuse F1 was blown, and the diodes in the HV bridge D6-D8, some tracks connecting them and the transistors. I decided to reverse engineer it and one thing that jumps out is that the HV bridge is not full, they have left out D5. There is a space for it, but its not fitted. Is that deliberate? I presume the device was damaged when run without liquid which apparently causes excess voltage due to resonant mismatch. Need to order the parts and see how the repair goes. Any thoughts welcome.

author: CapLeaker
author_rank: Regular Contributor
timestamp: May 04, 2025, 02:43:07 pm
content: Seems to me D5 was blown and someone took it out. Other than that the blown F1 fuse doesn’t make any sense.

author: CaptainBucko
author_rank: Regular Contributor
timestamp: May 04, 2025, 10:22:11 pm
content: D5 was definitely not factory fitted. The solder pads were smooth and clean, just like you get when running a NF fitted component over wave soldering.D9/D10 look fine (from my basic tests) so I'm concerned the issue was not excess voltage due to an empty tank, but excess current due to incomplete bridge rectifier. But I am also wondering if its standard to tweak peak to peak voltages by just removing a single diode from the bridge, and so this controller is matched with the ultrasonic transducer or something.

author: Andy Watson
author_rank: Super Contributor
timestamp: May 04, 2025, 10:46:58 pm
content: There is no significant power-storage betweem mains cycles, so the ultrasonic driver will be modulated by the mains voltage. Removing D5 effectively halfs the power output. Perhaps D5 is fitted for a more powerful version of this u/s cleaner?On the other hand, I think the most likely explanation is that D5 was either not fitted, or fell out before soldering and nobody noticed.

author: CaptainBucko
author_rank: Regular Contributor
timestamp: May 05, 2025, 04:17:21 am
content: Spice simulation of full bridge vs 3 diode rectifier. This YT shows other units with a 3-diode bridge, so I don't think it is a factory mistake.https://youtu.be/qTBEhsRkF9EInterestingly, if the simulation is correct, I can understand why leaving the diode out would give better performance from a cleaning action. I also suspect much less heat and power (average) just based on the waveforms.

author: CaptainBucko
author_rank: Regular Contributor
timestamp: May 12, 2025, 10:17:08 pm
content: Diodes and Transistors were replaced, and unit re-assembled. Tested with a tank full of water and a strip of aluminum foil for testing. Ultrasonic transducer initially powered up, and unit sounded OK. Sound was not consistent after about 20 seconds, smoke appeared around 30 seconds. Fuse popped around 45 seconds, and transistors are shorted again.The transformer that was smoking was the core of T3 and T2 (the main output coupling) transformer. Looks like excess current was still present - so not sure if this is due to transducer mismatch or breakdown in the windings of T3/T2. I should be able to remove the T3/T2 transformer and measure its inductance, just as a learning exercise. I will scrap this unit for parts as its not worth spending more time trying to fix it.

author: timeandfrequency
author_rank: Frequent Contributor
timestamp: May 12, 2025, 10:53:34 pm
content: Hello CaptainBucko,Measuring its inductance mjght not provide significant evidence.You can try toringit.UpdateWhat about a replacement board ? (could not find an exact match) :https://fr.aliexpress.com/item/1005003730414353.htmlhttps://fr.aliexpress.com/item/1005008582956300.html