Pedestal fan

[Howie393]

I am trying to repair a 11 month old fan. Have tested the motor, ok, so fault is with the PCB.
Q1 Input voltage is 230vac and after the fuse their is a resistor 330k, will it be ac or DC after the resistor?
Q2 the ic is unmarked, how do I find out what it is?
Can anyone tell me what this is in image 3. On PCB it is marked as 6.8mh

 

[danadak]

Take a picture, well focused, both sides of board.

A resistor drops voltage, but does not "convert" it. A rectifier converts
AC to DC, also solid state switches like MOSFETs can convert AC to DC,
and vice versa. You can have AC on one side of a R, DC on the other, or
AC on both sides or DC on both sides, depends on the circuit and its design.


Regards, Dana.

 

[MaxHeadRoom78]

Q2 If it is an AC motor, most likely a Triac.
What case style does it have.

 

[Ramussons]

An IR sensor, 3 Triacs, Flip-Flops / Latch. These are the main components.
Check the fuse, The diode D1, the Varistor.

 

[Howie393]

An IR sensor, 3 Triacs, Flip-Flops / Latch. These are the main components.
Check the fuse, The diode D1, the Varistor.

Checked fuse, diode d1, both ok. Where is the varistor?

 

[MaxHeadRoom78]

Blue disc object, top right.
Generally they have quite visible signs when they have failed.

 

[Howie393]

Blue disc object, top right.
Generally they have quite visible signs when they have failed.

Thanks found it. Biggest problem I have is cannot find any voltage at the ic. Unfortunately the ic does not have markings on it at all, tried with UV light but nothing.

 

[MaxHeadRoom78]

When circuit is operating normally, the VDR presents an almost open circuit, when it fails due to high voltage spike etc, it often destructs, so is visible.
IOW, the circuit will operate without it, just Sans protection.

 

[Ramussons]

This is a IR remote controlled unit. Do you have that Remote with you?
That Red arrow points towards an Inductor. You can short it and check for a voltage between pin 1 and pin 16. (16 positive wrt pin 1)