#### ptonsparky

##### Tom

Anyone have an idea which ones are the motor leads?
Black Red on the left smaller and Black Yellow on the right larger. Pure guess on my part.

#### zbang

##### Senior Member
Put a meter on what you think are the power leads and spin the motor, if you get a voltage that's probably the windings.

#### ptonsparky

##### Tom
Put a meter on what you think are the power leads and spin the motor, if you get a voltage that's probably the windings.
Duh. (Insert DAA emoji)
jeesh.

#### don_resqcapt19

##### Moderator
Staff member
about 2:40 in on this video

#### Jpflex

##### Electrician big leagues
For the fan on the left 12 v = 20i x R

Resistance (winding) = 12V/20i

Therefore your resistance for the motor winding will be around 0.6 ohms between the two leads to power the motor windings (positive and negative)

There's no impedance or reactance power factor other than unity 1 to worry about for dc circuits

#### Jpflex

##### Electrician big leagues
For the fan on the left 12 v = 20i x R

Resistance (winding) = 12V/20i

Therefore your resistance for the motor winding will be around 0.6 ohms between the two leads to power the motor windings (positive and negative)

There's no impedance or reactance power factor other than unity 1 to worry about for dc circuits
Unless there is solid state components integral to the fan as in the picture you can't use ohms as mentioned

#### Todd0x1

##### Senior Member
these are brushless dc motors, metering the leads wont give you anything useful. black+red, and black+yel as OP guessed. Yellow is DC+ if no red present. If red is present its DC+ and yellow is the tach output.

#### 4x4dually

##### Senior Member
I tried to google up a data sheet for that fan for fun. Nothing to be found that I can see. The OEM must be in a basement in China.

#### petersonra

##### Senior Member
I tried to google up a data sheet for that fan for fun. Nothing to be found that I can see. The OEM must be in a basement in China.
Foxconn is not a basement operation by any stretch.

#### grich

##### Senior Member
This is from the Cooler Master website...

#### 4x4dually

##### Senior Member
I tried to google up a data sheet for that fan for fun. Nothing to be found that I can see. [SARCASM]The OEM must be in a basement in China. [/SARCASM]

Foxconn is not a basement operation by any stretch.

Edited for the non-humor having engineers sitting on their protractors.

#### ptonsparky

##### Tom
Spinning the fan worked with the 4 wire but not the 3.

They both run when voltage is applied as suspected.