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  • Author Author: Jan Cumps
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when a mod goes wrong - failed attempt to add an external antenna

Jan Cumps

Modifications don't always go right.

Yesterday morning I tried to replace the PCB WiFi / BT antenna on a Avnet SmartEdge with an external one.

I had to place a fitting connector on a footprint and turn a resistor 90° to route the signal to it.

 

I got he connector off a launchpad that's no longer supported.

That wasn't hard, although it took a decent time to heat up the big ground plane.

 

image

 

The drama occurred when I tried to unsolder the tiny resistor with a hot air pencil.

image

The trace between the lower side of the resistor and the ceramic filter FL1 underneath it ripped off completely.

Various attempts to try and scrape a little bit of track from under the filter failed. So I had to remove it with hot air.

Then try to create my own little trace from underneath it.

 

Long story short, it didn't work.

I managed to restore all electronic connections (I buzzed everything through, but never got a BT or WiFi signal out).

I also tied to restore the original route with a tiny patch wire made with a transformer (enamel tactically removed at the right spots) wire.

It never worked again.

Tried this morning with fresh energy - and daylight - but again no success.

image

 

As you can see, my very last attempt - when I knew it was a lost case but gave it a shot anyway - turned the part of the board where the PCB antenna is, charred.

 

Officially not fixable anymore, I adapted the overlay to disable wifi and BT. I'm using wired network now.

On the + side, it gives me a chance to show you the underside of the PCB:

image

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