One of my ceiling fan with electronic remote speed control produces an arcing.. bishhhhhh….bishhhhhh… sound (like an electric shock sound) and it switches the fan speed from low to medium to high, and its like out of control. I have decided to inspect to see what is wrong with the electronics section. I have disassembled the bottom base control section away from the body of the fan motor.
Figure 1: Bottom base control section internal (PCB is sitting inside
the fan bottom enclosure so as the IR (Infra Red) receiver is mounted on
the bottom of the Light Filter lense.
All the high voltage capacitors needs to be discharged first! High
Voltages which are still present inside these capacitors can give you an
electric shock which is hazardous! It can kill you! Do not attempt to
do this on your own if you are not sure what you are doing! Do not
attempt to repair if you are not a qualified technician or engineer.
Figure 2: PCB removed from the enclosure.
Figure 3: PCB top view.
Figure 4: PCB bottom view (IR Receiver module on bottom side PCB).
Initial visual inspection does not show any sign of burn or component
spoil on the circuit board. My earlier guess was that the power section
which regulates power to the microcontroller that control the
functionality of the fan speed fails to work properly.
Figure 5: 1uF Regulator Capacitor and rectifier diodes.
Figure 6: Replaced by a 0.47uF 400VAC testing Capacitor.
I then inspected all the big film capacitors and polypropylene
capacitors, but they all looked ok. Next, I need to find out which
capacitor which drops and regulates voltage from the mains supply
(240VAC) to the microcontroller circuit. This capacitor will work
together with the rectifier diodes to produce low voltage direct current
(DC) to power up the microcontroller circuit. I have identified and
removed this 1uF 400VAC capacitor and should replaced it with a new
capacitor with the same value and voltage rating.
Unfortunately, I do not have this capacitor in my components tray, so
I have inserted a 0.47uF 400VAC mylar / Polyester Film capacitor for
initial testing. However, it works although its value is half of that
the original 1uF capacitor!
Figure 7: Testing with the new capacitor.
Figure 8: The old bulging 1uF 400VAC Capacitor.
The spoil 1uF capacitor seem to be bulging on the sides. Before I
put it back to use, I would want to change the 0.47uF testing capacitor
with the original value so as the bigger value 1uF capacitor can provide
sufficient current for the microcontroller circuit.