ULTRASONIC - Page 1
Forum section: electronics / beginners

author: HILIK148
author_rank: Newbie
timestamp: August 19, 2025, 02:44:36 am
content: Hello everyone,I recently bought a new ultrasonic cleaner, but it doesn't power on at all.Upon opening it, I noticed that the main control board (with buttons and 7-segment displays) has a 2-pin connector that is completely unconnected.On the power board, I found two clearly labeled and unused terminals — L and N — that appear to be intended to supply AC power to this connector.There are no loose or disconnected wires inside the device — it's just missing this entire cable.I’ve attached clear photos of both boards.My question:Could this missing AC (L/N) connection be the sole reason the device is unresponsive?And is it possible the manufacturer simply forgot to include this connection?I have basic electronics experience, but I’d like confirmation from someone more knowledgeable before I try to connect it myself.Thanks in advance!https://drive.google.com/file/d/1pY894FArGXbKiux23YatqvRDbdewxh2r/view?usp=drive_linkhttps://drive.google.com/file/d/1eE3BSBm44a1_ZzXROeOOtGHO9210f4Cx/view?usp=drive_link

author: Zero999
author_rank: Super Contributor
timestamp: August 19, 2025, 08:33:46 am
content: Sorry, but why are you even considering repairing it yourself?If it's new, then it's still under warranty, so return it, in exchange for a replacement or refund.

author: Gyro
author_rank: Super Contributor
timestamp: August 19, 2025, 08:44:05 am
content: It clearly didn't undergo any sort of production test did it. Return it and buy something else.

author: HILIK148
author_rank: Newbie
timestamp: August 19, 2025, 09:47:40 am
content: Quote from: Gyro on August 19, 2025, 08:44:05 amI did get a full refund for itBut before I throw it away I thought maybe I should fix it and enjoy the device

author: Sorama
author_rank: Frequent Contributor
timestamp: August 19, 2025, 09:59:17 am
content: I think you got yourself a free and soon working device…

author: HILIK148
author_rank: Newbie
timestamp: August 19, 2025, 11:43:10 am
content: Quote from: Sorama on August 19, 2025, 09:59:17 amOkSo is the problem I described really what's causing it not to work??Or is there another problem?Thanks

author: thephil
author_rank: Regular Contributor
timestamp: August 19, 2025, 12:03:21 pm
content: Caution:To me, the display/control board and its little connector don't look like they are meant to handle mains voltage! I'm pretty sure that the buttons (and controller) on the control board are meant to control the relays on the main pcb using something like 5V.So I advise against connecting things that way. At least, test the voltage on those spade connectors before wiring up anything.Also, it is not uncommon to have unused connectors. Manufacturers often use the same PCB for various models and populate things accordingly. E.g. there are unpopulated footprints for another relay and buttons on your pcbs.

author: Sorama
author_rank: Frequent Contributor
timestamp: August 19, 2025, 01:25:32 pm
content: follow the money.I mean, the voltage. measure AC input to the main board and check the voltages on the 2 connections going to the little board.It's just a matter of understanding where the voltage regulation is done and if these go to the little board or not.But first check how the AC is connected to the main board and how they derive the low voltages from there.

author: BILLPOD
author_rank: Frequent Contributor
timestamp: August 19, 2025, 01:49:23 pm
content: Good Morning HILIK148, What is the make and model of your unit?If you enter that information into your search engine of choice, (my favorite is Duck Duck Go), you may find other instances of what you are experiencing, or videos and reviews of the unit. Or maybe even contact the manufacturer. You have lots to explore before anyone can give you repair advise. Just be careful around the parts with mains voltage.

author: thephil
author_rank: Regular Contributor
timestamp: August 19, 2025, 03:36:01 pm
content: I support what Sorama says: You need to do some basic debugging here and checking supply voltage and where it goes should be the first step. I would guess that there is a pretty good chance of fixing this thing but you need to narrow down the actual fault, first. So get out your multimeter and let the fun begin