Why the UMO has fans on electronics?

[LePaul]

Divorce is popular in this country for noise reduction

[drayson]

Great.....

[johan]

I'd love to find a way to get rid of the noise (and the fan) once and for all.
Any recommendations?

There are two obvious alternatives, change the electronics board to some fan-less design or change the fan. Changing the fan seems to be the more economic alternative. I would try a Sunon blower fan and if there isn't one in exactly the right dimension a printed adapter should be fairly simple to design. (Might be worth it just to get rid of that awful origami fan duct.)

Getting a 2.1.x motherboard (UM2/UMO+) is an alternative, but that is pretty expensive and you probably need to upgrade to a pt100 temp sensor in that case.

[Titus]

You can also peel of the sticker and drop in some sewing oil once in a while.
YES the fan still makes noise, just quite some less.

Ideally I'd use drop in stepper replacements that don't require cooling, but hey

[LePaul]

I just had my UMO apart to replace the hot end and checked the electronics fan while wiring in the heater. It still has that initial rattle at start up but seems to quiet down after 30 seconds. I should think about replacing mine too

[drayson]

I already tried several fans, shrouds and blowers but found nothing real suitable and silent. bought 24v as well as 12v, modding parts and standard mouser stuff - over all 4 blowers and 3 fans...
if somebody finds a good and silent replacement - best just a drop in part, keep me informed