I have some additional information for those people that attempted this modification and failed because they measured a short across positive and negative terminals once they soldered the wires to the PMA flex.
Some background: Many people were sending me PM's asking why their flex would short-out after they soldered the wires on, and several people even included pictures (thanks!). Many people also reported that the Flex "started working fine" after they removed their modification from the PMA flex. After farting around with this for a couple of weeks and dissecting yet ANOTHER flex, I found the problem. Nokia's apparently using two different kinds or revisions of PMA flexes: One with black masking only, and one with a black masking over a thin, dark gray
conductive shielding layer. If you don't clean the black paint mask and dark grey conductive layer completely off the area around where you exposed the copper trace, your wire may short out to the conductive paint, which is electrically connected to ground elsewhere on the flex. This can cause your positive connection to short to ground.
The solution is to remove the black paint mask and dark gray conductive layer away from the areas where you dig into the flex to expose the copper. You can either carefully do this by scraping, or you can use a chemical solution and lots of Q-tips to solve it away.
I personally hate scraping, because there's no way to "unscrape" once you go too far, so I looked for a solvent that would work on this mask. I did some tests, and here are the results:
Ewww... MEK... Wonderful stuff... Causes cancer, clears up acne, and really flushes the senses... Makes you feel like you're alive and kicking...
or not... Breathe these fumes at your own peril.
I recommend that once you scrape down to the copper substrate that you clean/scrape the black/conductive mask away from that area completely to prevent the exposed wire(s) from shorting-out to the gray conductive coating. The orange mylar mask is not conductive, but the gray crud is VERY tenacious and may be hard to see without a scope, so be thorough! It
really likes to stay in the gap between traces, so carefully check the gap between (T-) and (+). If you look closely in the full-size image above, you can still see gray conductive material in the gaps between the traces, even on the side I used MEK to clean...
Once you clear the black mask and conductive layer away from the area you dug into, solder your connections and test for any shorts. If your exposed wire connection doesn't touch any of the gray material, you're probably good-to-go. If you see your solder work or exposed wire touching ANY gray coating, clean it away before finishing up.
Don't forget to test your modifications for shorts between (+) and (-), and (+) and (T-). Remember that (-) and (T-) should only be shorted
after you solder a connection between the two on the flex.
Good luck!
SonarTech