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How do I have a 12v hotend fan on a mini?  

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Rick Avra
(@rick-avra)
New Member
How do I have a 12v hotend fan on a mini?

Sorry if this is a silly question but I'm looking to replace the hotend fan on my recently purchased (used, modified) mini. The fan spins and appears to work but is a 2-wire fan (i.e. no RPM connection) so the fan test never passes.  The oddball thing is that the fan is 12V but it is attached to a Slice hotend. I know from the Prusa docs that the original fan is 5v so I'm wondering if anyone knows how this works. I haven't taken everything apart yet to see how it all wires together.

Thanks for any tips.

Posted : 28/11/2024 7:56 pm
_KaszpiR_
(@_kaszpir_)
Prominent Member
RE: How do I have a 12v hotend fan on a mini?

Provide some pictures, please.

Maybe someone used it with fan checks disabled?  But then the hotend heater on the mini is 24V so the fan should be 24Vz unless they did some additional modifications to the wirings...

See my GitHub and printables.com for some 3d stuff that you may like.

Posted : 29/11/2024 5:32 pm
Rick Avra
(@rick-avra)
New Member
Topic starter answered:
RE: How do I have a 12v hotend fan on a mini?

From this photo, I got the Delta fan part number for the original fan and it's datasheet shows that it is 5v.

In the first post I included a photo of my mini's hotend fan along with the Slice heatsink to which it is attached. Let me know if you're looking for other photos or if those photos didn't post for some reason.

I'm wondering if something in this Slice mod (maybe has a different extruder as well?) there is something that provides 12V to the fan but that doesn't make much sense since the hotend fan is only supposed to be activated once the temp gets above 50C and I'm guessing only the mainboard has the thermistor connection. Strange.

My plan is to get to the main board, confirm the hotend fan connection is to the normal place (and confirm that the RPM pin is not connected to anything), and then measure the fan voltage during operation (i.e. pre-heat). That should give me something to go on.

 

Posted : 29/11/2024 7:51 pm
3Delight
(@3delight)
Moderator Moderator
RE: How do I have a 12v hotend fan on a mini?

If a 12V fan is connected to a 5V supply it will probably just run slower I should think...  It sounds like the original owner replaced the 5V one and got the wrong spec.

Posted : 29/11/2024 11:21 pm
_KaszpiR_
(@_kaszpir_)
Prominent Member
RE:

>In the first post I included a photo of my mini's hotend fan along with the Slice heatsink
Oh now I see it,  previously I havent noticed two tiny vertical lines which led to 'heic' images (two of them are repeated, though).

Converted to jpeg:

Looks like a mix of:
- Slice Engineering Copperhead Hot block https://www.sliceengineering.com/collections/copperhead/products/copperhead-hot-block
- Slice Engineering Copperhead Heat sink (notice there are two versions, not sure which one is it) https://www.sliceengineering.com/collections/copperhead/products/copperhead-heat-sink

Could you please provide more zoomed out photos from both sides, top and the bottom?

I suspect there is also Slice Engineering Copperhead Heat Break P Mini between them https://www.sliceengineering.com/collections/copperhead/products/copperhead-heat-break

Other notes, if the fan is 12V and it runs on 5V then you are lucky, a lot of them do not start on such low speed.
What you could do is to replace it with something similiar (for example Nocuta).

I think some cables can be masked, they are there but not well visible.

See my GitHub and printables.com for some 3d stuff that you may like.

Posted : 29/11/2024 11:55 pm
_KaszpiR_
(@_kaszpir_)
Prominent Member
RE: How do I have a 12v hotend fan on a mini?

>Slice Engineering Copperhead Heat Break P Mini between them ...
Hm I think I'm wrong here and there may be a different connection, I wonder what is above the heat sink and how the filament is fed 🙂

So please more photos which take the whole printer into the frame.

See my GitHub and printables.com for some 3d stuff that you may like.

Posted : 30/11/2024 12:08 am
Rick Avra
(@rick-avra)
New Member
Topic starter answered:
RE: How do I have a 12v hotend fan on a mini?

Thanks. Will do. I'm away from it today but I'll post tomorrow.

(And I'll make sure to post photos as jpegs 🙂 )

 

 

Posted : 30/11/2024 1:39 am
Rick Avra
(@rick-avra)
New Member
Topic starter answered:
RE: How do I have a 12v hotend fan on a mini?

I haven't followed the wires all the way through the bundle but it appears that the 12v hotend fan is just being driven by the main board and I confirmed that voltage is 5v. The fan does start reliably but obviously, this doesn't seem smart - a 12v fan being driven by 5v and without an RPM signal. I figure *any* 5v RPM fan that fits will be better suited than this one!

For the curious, below are more photos of this strange setup (though it looks like the forum crops photos on import).

Posted : 30/11/2024 9:12 pm
_KaszpiR_ liked
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