Doubt on which type of film capacitor to use

Thread Starter

Jw512414

Joined Aug 26, 2020
4
https%3A//i.ibb.co/wCPxShQ/IMG-20200826-174720.jpg[/img]']

Hi. I have a PCB which has a faulty Panasonic ECQ-UL polyester film capacitor that needs replacing. The capacitor is used as a capacitive power supply and the board goes haywire when this cap becomes faulty. The board is from a ceiling fan and is exposed to some heat from the motor when in operation. The original one only lasted about 4 years.

I'm looking for an option that can hopefully that is hopefully more durable and lasting. Any advantages of choosing a polyester vs polypropylene? Below are the options I have.

1. Panasonic ECQ-UL polyester film (identical to what the manufacturer put in) 275vac
2. Panasonic ECQ-UA polypropylene film 275vac
3. Panasonic ECQ-E polypropylene film 630vdc
4. Vishay MKT 310vac

If anyone could advise which one would be the best, greatly appreciated.
 

bob2

Joined Jun 15, 2019
200
https%3A//i.ibb.co/wCPxShQ/IMG-20200826-174720.jpg[/img]']

Hi. I have a PCB which has a faulty Panasonic ECQ-UL polyester film capacitor that needs replacing. The capacitor is used as a capacitive power supply and the board goes haywire when this cap becomes faulty. The board is from a ceiling fan and is exposed to some heat from the motor when in operation.
Hi
Have you tried to analyze the reasons that cause the failure of this film capacitor?
What are the parameters of a film capacitor after failure?
 

AlbertHall

Joined Jun 4, 2014
10,397
The usual failure mode of these capacitors in transformerless power supply circuits is that the capacitance value reduces until the available current is no longer sufficient for the circuit to operate.
 

bob2

Joined Jun 15, 2019
200
The usual failure mode of these capacitors in transformerless power supply circuits is that the capacitance value reduces until the available current is no longer sufficient for the circuit to operate.
Well, let TS show or tell how much the capacity has decreased. Or is there another reason for the failure? Maybe a short circuit?
 

BobaMosfet

Joined Jul 1, 2009
1,208
would really like a larger picture of the faulty capacitor.... I get a web error if I click on image (404), and my old eyes can't make out the writing...

:)
 

Thread Starter

Jw512414

Joined Aug 26, 2020
4
Hi
Have you tried to analyze the reasons that cause the failure of this film capacitor?
What are the parameters of a film capacitor after failure?
It's reading 0.18uF in this case when the original rating is 0.82uF.

It's a common fault among these products and you can see the repetitive failures in the picture below. The capacitance drops over time until the board becomes unusable. I suppose it's bad design/planned obsolescence or something. Normally I'd just use back the same thing but hoping to gain some insight to see if there's anything I can do from a component standpoint to improve the lifespan.
 
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