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Jon Elson[_3_]

wrote:

On Tuesday, November 8, 2016 at 3:42:12 PM UTC-5, Jon Elson wrote:
wrote:

On Tuesday, November 8, 2016 at 7:21:17 AM UTC-5, N_Cook wrote:

Much Snippage

Questions:

a) What is the actual resistance in ohms of the OEM fan and the
replacement fan if measured across the contacts.

Meaningless. These fans have a commutation circuit and some FETs in
them, so you will not read anything that resembles a resistance on them.

Jon

No. The two that work ohm out at ~10 meg. The two that do not ohm out at
~20K. So, yes, you are seeing 'resistance' on them. Clearly "these fans"
are not created equal.
But, clearly, if it was TRULY a 10 Meg resistor, the fans would not produce
any airflow. When you get enough voltage on them, the circuitry turns on
and starts drawing current to spin the rotor.

The 20K ones might have a popped component, or just a different control
circuit.

Jon