Ender 3 fan not running - seeking diagnosis advice please

[ThreeDeeMan]

I am running an Ender 3 Pro. All standard stuff just using PLA. No mods. Yes, a newbie.
Printer is about 3 months old.
Prints started to fail and I noticed that the fan that cools the hot end (extruder part) was not running.
I bought a new fan. I cut off the old fan and tested it on a 24v battery. It worked!!
A voltmeter on the supply wires from the main board showed just a few millivolts.
So I suspect the main board has failed. But all other aspects of its performance are working.
Before I go buy a new one, I would appreciate the view of experienced 3D print experts.
Does my diagnosis make sense? Do boards fail in that way? Just seems odd to me that a single 24v supply isn't working.
3DM

[AutoWiz]

Assign it to a different pin on the mainboard. Depending on what mainboard you have that is. If the mainboard has an unused heater like for E1 then you can re assign that to be your fan pin, for example. But just to be sure it is your mainboard how and where are you testing for power? The fan should be unplugged from the mainboard and you should be testing the pins on the board. I say this only because if the power wire touches ground it will be pulled down to 0v and if the wire is broken and you are testing for power at the extruder then you will not see the power at the mainboard and both are potential causes as them wires move about as the printer runs.

[xayoz]

look at BTT E3 Mini 1.2 or 2.0 mainboard. For the price it may not be worth messing around with the old board, plus it moves you to a 32 bit silent board.

[ThreeDeeMan]

Thank you both.
Your help appreciated
3DM

[curious aardvark]

you say you tested the supply 'wires' - did you test the pins in the actual socket or just the wires ?

Broken wires are really common- had a few over the years - dead fan sockets - not so much.

There may also be a second fan socket. no clue what board creality went with for the ender 3 v2.

[ThreeDeeMan]

you say you tested the supply 'wires' - did you test the pins in the actual socket or just the wires ?

Broken wires are really common- had a few over the years - dead fan sockets - not so much.

There may also be a second fan socket. no clue what board creality went with for the ender 3 v2.

Problem solved. Wire broken.
Thank you.
3DM