FAN Repair
I had accumulated three floor standing fans which had stopped rotating. Had cleaned and oiled its shaft bearings and even changed the squarish capacitor but still not turning. Was about to throw them away when I thought "... what's the harm in dissecting them, I could learn something from it...!!"
I had asked a few servicemen and all I got was a short "...there's an internal thermal fuse...". I trawled the web for months but just could not find any info on where the fuse was and how to replace it. Finally I decided to sacrifice one of the fans and dissected all the wires going into the windings.
From this came the schematics of the fan, but only up to the motor windings.
This instructable comes in 2 parts: (I)Troubleshooting and (II)Fuse replacement.
Cross head screw driver Flat tip screw driver Scissors or Pen knife Soldering Iron and some Solder Some string about 0.5mm in diameter Spare wire, about 60cm long Capacitor 1.4uF 450VAC (if required) Thermal Fuse 130degree C, 1A, 250Vac  (note: I could only find a 2A 130deg replacement @$1.50SGD a piece from the local electronic component shops. Sorry I don't have equivalent part number from Mouser, RS n Digikey)
WARNING:
If you are NOT trained in electrical repair, please STOP here. It would be wise to spend the money for a replacement fan and give the faulty one to someone who knows. We are dealing with 250VAC, so be extra careful. You proceed at your own risks.
The Schematics :
At this juncture, I assume you know and have verified that the timer and speed selector are working fine (i.e. voltages are present at output of the speed selector (grey, orange and red wires)), see schematics and picture.
The colors of the wiring used in my fan may be different from yours, so make a note.
Troubleshooting the Thermal Fuse :
1. Disconnect power to the fan. 2. Open up the control unit cover. 3. Take your time to trace the wiring and note down its color and location. It should be similar to the schematics above. 4. Using the spare wire, connect from point “A” to “B” to shunt the fuse. For my case, “A” was the blue “neutral” wire on the terminal block and “B”, the grey wire on the big squarish capacitor. Once done, make sure your fan (without the blades of course) is resting properly and securely as we are going to power it up. 5. Connect and power up the fan motor. If the fuse is faulty, the motor will rotate, mine did. If it did not, it might also be that point “C” was used instead of “B”, since you could not know which terminal it was. No worry. 6. Disconnect power. Move point “C” to “B” and power up the fan again. If it still would not rotate, it’s likely the capacitor. 7. Disconnect power and remove the spare wire.
Replacing the Capacitor:
1. Disconnect power. 2. De-solder (or cut) the wires at capacitor terminals and connect them to a new capacitor (same type). 3. Power up the fan. If the motor still refuses to rotate then I believe the problem is with the motor windings and it's time to say bye-bye to the fan.
Removing the Thermal Fuse:
Disconnect power to the fan before proceeding.1. To make fuse replacement easier, we need to free the motor from the control unit keeping its wiring harness as long as possible. The harness has 5 wires going into the motor housing. By tracing this harness, starting from the motor housing, I found the Ground (green/yellow) and Neutral (blue) wires ending at a terminal block and another three (grey, orange, red) ending at the speed selector.2. Remove the Ground and Neutral wire (no cutting required) from the terminal block. De-solder  the grey, orange and red wires at the speed selector, note their location first. (You may have noticed that I cut the whole harness about 10cm from the motor…big mistake...but that was way before I decided to do this!!)3. Using a flat tip screw driver as a lever, pry the motor housing mount rod away from the control unit.4. Remove the oscillating unit and detach the capacitor.5. Remove the metal housing screws. Carefully remove the rotor and the windings slowly by giving it enough slack from the harness.
