PC Fans  - Page 1
Forum section: electronics / beginners

author: vinlove
author_rank: Frequent Contributor
timestamp: July 25, 2019, 11:27:58 am
content: I got 2x fans from old ATX PC case. Not sure if they were for the processor or just cooling fan in the case.They are quite small, and each has red and black cable coming out from the core, and it says on the fan 12V.So I connected them to my PSU, and turned to 12V. But no action. The fans are just still, not moving.I got my DMM and checked resistance of the red and black cable, and it reads 10M ohms. Both are similar resistance.Are these fans dead? Or what? Why are they not working with 12V supplied to them. There is no switches, just two cables from the fan.

author: madires
author_rank: Super Contributor
timestamp: July 25, 2019, 12:56:55 pm
content: Do they spin freely when turning by hand?

author: Brumby
author_rank: Unknown
timestamp: July 25, 2019, 01:04:15 pm
content: Wouldn't matter much whether they spin freely or not - for a 2 wire fan, 10M ohm = dead.

author: vinlove
author_rank: Frequent Contributor
timestamp: July 25, 2019, 03:38:02 pm
content: What sort of reading should it be, if they were in working condition?

author: Monkeh
author_rank: Super Contributor
timestamp: July 25, 2019, 03:45:37 pm
content: Quote from: Brumby on July 25, 2019, 01:04:15 pmI just grabbed a 12V 2 wire fan I know to be working. It reads around 19MΩ. So.. no, not that simple.Assuming you got the polarity correct, they're likely just plain dead.

author: vinlove
author_rank: Frequent Contributor
timestamp: July 25, 2019, 05:54:38 pm
content: Quote from: Monkeh on July 25, 2019, 03:45:37 pmI connected the red wire from the fan to +, and back wire to - on the PSU.I wonder if I should try reversing the polarity? Would it not then blow the parts? (if they are wrong way round, and have not been broken still).

author: Gyro
author_rank: Super Contributor
timestamp: July 25, 2019, 07:31:02 pm
content: Pretty well all PC fans have brushless motors. They most definitely do care about polarity, reverse polarity will kill them - possibly why they are not working in the first place.

author: Monkeh
author_rank: Super Contributor
timestamp: July 25, 2019, 07:32:09 pm
content: Quote from: Momchilo on July 25, 2019, 07:27:48 pmNonsense. Two wire fans in this context are brushless motors and they absolutely care about polarity. You can't run them in reverse.

author: vinlove
author_rank: Frequent Contributor
timestamp: July 25, 2019, 09:04:11 pm
content: So it looks like these fans are well goosed. Thought I could use it to add to my Apple MacPro 1.1 massive desktop, which has been running for 12 years (yes since 2007). The MacPro seems running a bit hot with this warm weather recently.

author: Gyro
author_rank: Super Contributor
timestamp: July 25, 2019, 09:09:01 pm
content: Fans have improved a lot in the past 12 years. Quietness (some have Fluid dynamic bearings, like HDDs) and airflow (blade design). Those old ones were probably getting noisy anyway. Treat yourself to some new ones.

author: pcmad
author_rank: Regular Contributor
timestamp: September 02, 2019, 08:42:57 pm
content: hook 12v to it and see

author: tooki
author_rank: Super Contributor
timestamp: September 02, 2019, 08:53:17 pm
content: Quote from: vinlove on July 25, 2019, 09:04:11 pmHave you vacuumed out the heatsink fins?