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jbvid
13-03-2007, 07:39 PM
Changing a S E C Chip.
I have used a soldering iron before but I am not a specialist.
A bit of a big challenge for me and all interested parties who may have a faulty Nokia DBox 2 Avia 500 as I had.
Firstly my thanks go to fergalsworld on this site who pointed me in the right direction after he looked at my bootlog file.
DAY 1.
I started by stripping the motherboard out of the Nokia then de-soldering and removing the front metal shield which runs all the way across the front of the board near the S E C Chip. I managed to leave the twin stacked card slots in place. I got myself a new sharp scalpel knife and carefully cut through all the 120 pins very close to the black square center of the chip leaving all the pins behind still attached to the board. Then with a very small pair of tweezers, very small soldering iron (0.4mm tip) and a magnifying glass removed all 120 pins from the board pads.
DAY 2.
Once I got this far pretty easily I continued to order the chip from the site that sells a lot of second hand and new Nokia and Sagem stuff (Linux).
On the arrival of the new chip (only about a week on order) I continued by smoothing the 120 pads down with the small soldering iron to make surface pads as flat as possible. The next part was the most difficult because I had to put a sticky pad on the top of the black chip center then press my finger on it to hold it steady whilst lowering it squarely onto the pads. I started by soldering one corner pin then moved to solder the three other corner pins.
DAY 3.
I continued today which was getting more difficult due to the closeness of the pins even with the 0.4mm soldering iron tip which seemed too large for the job but couldn't find any smaller. I slowly managed to solder down one side of the chip (40pins) then called it a day.(after a couple of hours, eye strain)
Day 4.
I sharpened the tip up and got on better by doing two more sides of the chip before calling it a day.(after a couple of hours, eye strain)
DAY5.
Finished soldering final side today or at least I thought so. On checking over all the work with a long sewing machine needle I found quite a few pins that were moving and not firmly soldered onto the pads so I resoldered them.
Assembled board and connected up and presto, working box. I don't think I will tackle another one for a year or two.
jbvid