Messed up the wiring in a 3 speed box fan, how can I fix this?
Do you have a multimeter? Specifically an ohm meter to measure continuity and resistance? Motor wires not necessarily color coded. But we still can find out.

If you have it you may follow these  steps:-


Out of 6 wires, see which one is directly linked on metal casing of the motor. This is the protective earth wire. This must go to the ground terminal of the mains plug directly. You should read zero ohm between this wire and motor body.


Now you have 5 wires left to work on. Prepare paper and pen to take note the resistance readings.


Select one wire as reference and measure the resistance of all other wires against it. Tabulate your findings on paper.


After few rounds of measurements, you should be able to see each wires having different resistance which can matched up with wiring diagram such as this below.



Take note higher speed wire having lowest resistance and lowest speed wire having highest resistance.  The wire designated for capacitor, its resistance depends on motor horse power. This wire is connected to the condensor coil of the motor.

Your capacitor should have the capacitance marked in microFarads (uF). CBB51 not telling anything. Higher the uF, lower the resistance of the condensor coil.