Can anyone help me out here - I applied 24V to a 5V board

Thread Starter


Joined Sep 7, 2021
Hi, I made a bad mistake and plugged in the wrong amount of volts into the board. 24volts and not the 5volts the board needed. as you can see its blown a part. I have know idea if this can be repaired. The blue round part has been completely destroyed and there are no longer any id marks on it. I am not sure if any other components have been damaged or not. Can anyone I’d the round blue component so I can purchase a new one and hope for the best. Thanks, michael 58D5ED76-D703-4DC9-9826-5A4CF0C23A20.jpeg58D5ED76-D703-4DC9-9826-5A4CF0C23A20.jpeg


Joined Mar 30, 2015
Welcome to AAC!
The blue round part has been completely destroyed and there are no longer any id marks on it. I am not sure if any other components have been damaged or not. Can anyone I’d the round blue component so I can purchase a new one and hope for the best.
It would be helpful if you could trace the components around the part you think was destroyed and make a schematic.

From the shape of the component, it looks like it might have been an overvoltage suppressor, a PTC fuse, an inrush limiter, ...


Joined Jan 23, 2018
We had exactly the same thing happen a few years back, a tech applied 20 volts to a logic board that was supposed to run on 5 volts. ALL f he active components were destroyed as well as many of the capacitors.
If you are fortunate and VERY LUCKY only the incoming power section has been damaged, and can possibly be repaired. If not, probably the only undamaged components are the heat sinks.


Joined Aug 1, 2013
Visually, it looks like the majority of the board survived, but the on-board buck regulator power supply died. There are thru-hole components on the other side of the board that are important. Photo - ?

Also, there are three blue round components ...



Joined Aug 16, 2016
It's not an easy fix at any rate. Is the device expensive? Replaceable?
If not expensive, and replaceable, replace it.
If its expensive and replaceable, I think i'd still replace it. Or perhaps get a quote from a local electronics repair shop where they have the skills, tools and experience replacing similar components, along with the diagnostic tools to determine the extent of the damage. Expect to pay a nominal fee for the diagnosis.
If its not replaceable, take it to a shop. You could do more damage than good trying to fix it.
If you have nothing to lose by destroying it (more) and its a hobby project, have a go at fixing it, theres lots to learn and skills to develop. But without all the details, we cant be much help. A schematic would tell us if there was any over voltage protection on the board... but if its a commercial product not likely available.


Joined Jan 23, 2018
Those blue things were electrolytic capacitors, and if you are really fortunate they took all of the power as they were damaged. Usually they are not a very critical value, and the important rating is the working voltage. And being through-hole mount they are not so bad to replace.

Now for questions: Was the board only a 5 volt system? or was there a 24 volt portion as well? If the entire board is only five volts then the caps only need to have a rating suitable for that, such as ten volts. But if the board uses multiple voltages it will be a lot more complex.. So next question: What is the board, and what was it used for? and is there any circuit information available?

Thread Starter


Joined Sep 7, 2021
Thanks chaps, the board is only 5volts, it’s a control board for a CNC milling machine. With import duties it’s a fairly expensive item, so if a few Bob may fix it, it’s worth a go. Michael


Joined Jul 30, 2017
If you have an electric dishwasher, (I found it strange on my recent 2 month visit to Europe that few homes have dishwashers), put it alone on the top rack with 1/4 cup DW soap and run it. Open the door after it gets to the last cycle where it heats up...the open door allows the moisture to rapidly escape. OR, with a sink full of hot soapy water, and with a clean bristle brush, thoroughly clean the board than rinse in clear water. Wash top and bottom of the board. Allow to completely dry, than take photos and post here so we can see what's really needed to do the job. That blue device on the right looks like a special high voltage cap in the 0.1uF range, the device on the left that may have been blue once looks like a inrush current limiting device as mentioned earlier. Those square devices on the bottom of the picture may be electros and you may be able to guestimate their value by their size and function in the circuit once you draw it out. They could also be power diodes. That device with 150 marked on top looks like a coil with a powdered iron core held in place with epoxy. It may be open circuit now. The 150 may mean 150 uH.
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