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wz3k · 03-10-2013, 15:59

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"
iphone4_No_servicebmp.jpg

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.
draw_0310_1.jpg

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..

03-10-2013, 15:59	#1 (permalink)
wz3k Junior Member Join Date: Feb 2013 Posts: 19 Member: 1891566 Status: Offline Thanks Meter: 1	Reballing Skyworks SKY77541 problem 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" iphone4_No_servicebmp.jpg 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. draw_0310_1.jpg 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..