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Can't figure out why rear defroster isn't working after reattaching broken tab

1K views 4 replies 2 participants last post by  EOD Guy 
#1 · (Edited)
This is on a 98 Cavalier. Sorry for the long post. Fuse is fine, and power is going to the tab. The driver side rear tab came off the glass. I have an old friend who is very savvy with small electronics so I took it to his house and let him try to solder it back on with his gun and rosin core solder. Thought it would be easy. This turned out to be a big mistake. It would not take to the glass and made a mess of the area around where the connector goes.

Next I went and bought one of those microscopic $16 Permatex kits for reattaching the tab. I used the small sandpaper square to get off all the hard rosin residue, unfortunately this meant sanding into the part of the grid under the tab. I was not overly concerned though because the conductive adhesive seemed like it would solve any problems from sanding. And the instructions say to sand the area.

After allowing the right cure time the defrosters still did not work. So I used the bottle of conductive copper grid paint they also include in the kit to paint the tabs and glass surface to the three grid lines. This still did not fix it. I made my own test light and the tab itself has power but for some reason it will not transfer to the grid or even the surrounding painted surface. This copper paint is meant to replace a torn grid line, I would think it should work.



and one showing the test like working on the painted tab, move it off the tab foot and it doesn't light.




I'm not sure if that adhesive is causing a problem, or the original footprint for the path of 12v did not flow together from both tab feet, maybe they are supposed to be separated, going to different grid lines.
 
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#4 ·
Ok, I guess the adhesive Permatex supplies only works if the old solder points are still on the glass. If I touched a wire from the tab to the grid the defroster worked fine. I will have to relocate the tabs to the bottom right corner of the square. I made a temporary fix for now that is working well.
 
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