I was able to buy a replacement capacitor on eBay for $9.50 landed at my home. The garage door opener now works perfectly.
In an idle moment I disassembled the failed capacitor to see 'what made it tick'. As the pictures below show, it is a regular waxed paper dielectric capacitor. I identified the failed area as an area where the paper was completely dry. Exactly why that section was dry remains an open question.
The capacitor is made up of 2 plates of dimensions 22 inches long by 2 inches wide and made of a thin conducting material with a rough surface. I understand that the roughness increases the surface area and thus the capacitance. We all understand how this works as a capacitor...
What is a mystery to me is the inclusion of a 3rd conductor made of the same material as the two plates. This piece is 48 inches long by 2 inches wide and appears to be overlapped by a few inches with one of the two plates. In other words in electrical contact with one of the plates.
Thus one plate has a much larger surface area (I believe) than the other.
A Google search did not reveal the answer to me.
What purpose would that 3rd conductor fill?
Does anyone know the answer?
|Outer protective sheath with specifications.|
|Removed inner components still rolled up|
|The two plates showing wire connecting points. The mystery 3rd element and the waxed paper dielectric.|
|Installed replacement starter capacitor bought on eBay|