I sometimes boast about my old SMD soldering skills to my "happy hacking" friends... It's quite safe, until someone actually asks you to do _this_! Alex bought some of these JeeNodes from JeeLabs and needed some help. I accepted the challenge...
Before we start, a word of wisdom... Don't try this at home if you don't have the right tools, if you are uncertain about your tools or your ability it is best to send the module to JeeLabs and he'll repair it for you.
Following the site it is easy to understand the problem, Vout and Vin are connected to the wrong sources (this is a linear regulator Vout must be lower than Vin). The solution appears easy but it was not clear from the pictures, once the IC is in the vertical, there are two sides to chose from.
I usually start with the board to repair over a clean sheet of paper, makes easier to see as there's a better contrast, also if some small components come off the board or need to go in they're easy to see.
I then apply a small blob of solder to each side of the IC. The blob keeps liquid for some time and allows you to heat the other side (it must be a quick movement), once both sides have liquid solder slide the IC off the PCB to the paper.
Then using solder-wick clean the excess solder on the pads and on the IC feet.
I then marked the pads and the IC feet with the numbers and visualized what I had to do.
The IC actually is placed in "dead bug" style (but sideways), this means that the IC is "top-to-bottom", it is not so clear in the JeeLabs pictures.The mechanical pencil is 0.3mm for reference.
Finally I used some wire-wrap wire to connect the "floating-pad" to the board.
Since I have no idea how to connected to the JeeNode, connected it to the USB port and checked if the output voltage was around 3V... Some LEDs blinked (like in Arduino's FTDI), no smoke or hot ICs, I suppose it's fine...
SMD reputation intact...hopefully :-)
PS. - google.reader.friends if you have two posts one with pictures and other without pictures, it's just me and my faulty brain...
1 month ago