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wz3k 03-10-2013 16:59

Reballing Skyworks SKY77541 problem
2 Attachment(s)
Today I have an iPhone 4 with "Searching" and "No Service" problem. I bought it cheap. Checked the antenna path all seems to work fine, replace the antenna, clean the metal contacts still no success. I even changed the main board into another housing still no success.

I found the instruction below in this forum. First try, I reheat the two ICs with 285 C, for slightly over one minute each. Success!! but it lasted only like 5 minutes. In this 5 minutes, it found signal, 3G and 2G, can make calls and everything. But then it went back to "Searching" and "No Service"
Attachment 302115

So, I decided I want to reball the SKY77541. Then I hit this problem.. I was using 180C to preheat, then 300C, airflow setting 4, to unsolder the IC. Probably while I was lifting it, the small capacitors and resistors got pushed away.. I managed to resolder the IC back but now some of the small components are gone: C37_RF, C42_RF, C114_RF, C60_RF, R_35_RF, C63_RF, L9_RF, C165_RF,L5_RF.
Attachment 302113

My questions:
1. What can I do now? Can I just jump some of the components?
2. Was I using the right temperature and airflow setting? Too much? Too little?
3. How to ensure in the future I don't mess with the components around an IC while unsoldering with hot air gun?

I'm a newbie technician trying to learn. Please give me some pointers.. Thank you..

cal_guy 03-11-2013 05:41

Is it still turning on????

Important parts you should either replace or jumper them:
R_35_RF, L9_RF

wz3k 03-11-2013 10:16

Thanks for the reply. I have not tried to turn it on yet. Will do later and update.

ribsoft 03-12-2013 00:10

iff u reballing the SKY77541 dont use more than 240c, u burn insides of ic.

wz3k 03-12-2013 05:00

thanks. perhaps I have indeed burn the ic inside.. now the iPhone can still be on, but it is stuck at Connect to iTunes logo. Will try to replace it with another IC from another broken motherboard..

what about desoldering temperature? Can 240c desolder the IC from motherboard?

Originally Posted by ribsoft (Post 9262046)
iff u reballing the SKY77541 dont use more than 240c, u burn insides of ic.

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