GSM Coolhawk
07-23-2004, 03:02
@All
One more for today.
havent you all been pissed off when a 7650 flex cable have been ripped, either by the client, or even worse, by yourself, done that a few times myself :D duhh
Those flexies are still quite exspensive, and it take some time to fit a new new, but what if you dont have a new one ? Then your busted, and clients start screaming hehe (C) Crew
Well I did that some time ago with a clients phone upss, and did not have any flex cables in stock at the time, and wouldn't have for a few weeks to come. soooo lets get started.
Tools needed for this fix :
1 : A good stereo microscope or lupe, min 20x, I prefer to do this fix in 40x magnification !
2 : 30-50 W SMD soldering iron
3 : Cobber wire 0.2 mm
4 : Good flux, I recommend ERSA - FMKANC32-005 non-clean cream.
5 : Soldering tin 1.5 - 2 mm with core flux
6 : Doctors scalpel
7 : Some very steady hands
Note that this fix can ONLY be done if the flex cable have been ripped just above the pads on the PCB, if it's ripped other places, this fix does not apply.
First you'll have to cut the flex just where the rip has occured and make a nice strait cut all the way. Find your scalpel. In order to have the flex steady, I always put it back on the PCB and line it up with the pads.
What you do now is to start scraping of the plastic of the flex very very carefull, the lines are VERY fragile, one mistake and you can throw that flex away for good. As soon as you reach the thin cobber line under the plastic, take it even more slowly, you have to clear at least 2-3 mm of the line. When you after some nervous time have done this to the hole flex, it's time to prep it.
Apply flux on all the lines which are now in the free, and after prep them with some good solder. After this you can start to mount the wires. You need something like 3 mm on the flex and 3 mm on the pad. What I do normally in this kind of operation is to have a long cobber wire at hand, start to solder it to the flex first, then the pads, then you cut it, it's nearly impossible to control a 6 mm long patchwire trust me.
Under here you'll see the finished result of a ripped flex, which I've fixed by the above method, you should have an idea now what this takes.
http://www.gsmcoolhawk.com/gsmforum/repairpics/7650_Flex_1.jpg
Under here is a close up in 60x magnification.
http://www.gsmcoolhawk.com/gsmforum/repairpics/7650_Flex_2.jpg
Hope this helps out some folks. Good luck, and dont blame me for busted boards, do this at you own risk !
And please, do not start any "send me too" posts of any kind, they will be deleted. I do not have it whatever it might be. For your information I use a Novex AP-8 stereo microscope, and pictures posted here is taken with a QX3 Intel (tm) digital toy microscope, you can find those nice little ones on Ebay for around 60 Euro.
Regards
One more for today.
havent you all been pissed off when a 7650 flex cable have been ripped, either by the client, or even worse, by yourself, done that a few times myself :D duhh
Those flexies are still quite exspensive, and it take some time to fit a new new, but what if you dont have a new one ? Then your busted, and clients start screaming hehe (C) Crew
Well I did that some time ago with a clients phone upss, and did not have any flex cables in stock at the time, and wouldn't have for a few weeks to come. soooo lets get started.
Tools needed for this fix :
1 : A good stereo microscope or lupe, min 20x, I prefer to do this fix in 40x magnification !
2 : 30-50 W SMD soldering iron
3 : Cobber wire 0.2 mm
4 : Good flux, I recommend ERSA - FMKANC32-005 non-clean cream.
5 : Soldering tin 1.5 - 2 mm with core flux
6 : Doctors scalpel
7 : Some very steady hands
Note that this fix can ONLY be done if the flex cable have been ripped just above the pads on the PCB, if it's ripped other places, this fix does not apply.
First you'll have to cut the flex just where the rip has occured and make a nice strait cut all the way. Find your scalpel. In order to have the flex steady, I always put it back on the PCB and line it up with the pads.
What you do now is to start scraping of the plastic of the flex very very carefull, the lines are VERY fragile, one mistake and you can throw that flex away for good. As soon as you reach the thin cobber line under the plastic, take it even more slowly, you have to clear at least 2-3 mm of the line. When you after some nervous time have done this to the hole flex, it's time to prep it.
Apply flux on all the lines which are now in the free, and after prep them with some good solder. After this you can start to mount the wires. You need something like 3 mm on the flex and 3 mm on the pad. What I do normally in this kind of operation is to have a long cobber wire at hand, start to solder it to the flex first, then the pads, then you cut it, it's nearly impossible to control a 6 mm long patchwire trust me.
Under here you'll see the finished result of a ripped flex, which I've fixed by the above method, you should have an idea now what this takes.
http://www.gsmcoolhawk.com/gsmforum/repairpics/7650_Flex_1.jpg
Under here is a close up in 60x magnification.
http://www.gsmcoolhawk.com/gsmforum/repairpics/7650_Flex_2.jpg
Hope this helps out some folks. Good luck, and dont blame me for busted boards, do this at you own risk !
And please, do not start any "send me too" posts of any kind, they will be deleted. I do not have it whatever it might be. For your information I use a Novex AP-8 stereo microscope, and pictures posted here is taken with a QX3 Intel (tm) digital toy microscope, you can find those nice little ones on Ebay for around 60 Euro.
Regards