iphone 4s wifi need help troubleshooting. - GSM-Forum

dutch_anykey · 11-27-2014, 16:29

hi,

Strange thing with iphone 4s wifi problem.
Fixed several 4s phones already by exchanging wifi chip.
Now I have on that is making some trouble. put new chip on it already 3 times.

on startup greyed out wifi slider problem remains, no wifi hardware adress.
When i start uo and firmly hold my finger on the wifi chip, it comes up and works. I know first thing you would say is bad soldered chip. But on last solder i made sure all the black glue was gone. And when flowing started i could see the chip slide on its place. 99% sure that the wifi chip is soldered well on it.

maybe a pad lost connection to its underlying layer?

Also i lost R49_RF and C13_RF. I directly jumpered the output to the coil L1_RF.
Like I said when i apply pressure to the wifi chip, everything is working. Seems tat it is not missing the RC combination. (Iwill solder them back with components from another phone)

Can someone tell me what the fuction of C13_RF is? And strange that R49_RF is 0 ohms value.

Could it be related to my problem?

kind regards

arvaser · 11-28-2014, 00:50

hello, remove it and check with tweezers that all pads are connected. also maybe there is a problem with the PCB that causes this problem. friend of mine told me that he got iphone 5c without IMEI, he reballed the baseband and it was still the same. but when he pressed the ic it got imei back.. so sometimes it might be problem with the PCB.

dutch_anykey · 11-28-2014, 08:46

Hi arvaser,

Thanks for the reply.

I desoldered the chip again and checked the pads. Pin 10 > "HOST_WLAN_HSIC_RDY" is crooked. Maybe you know what this pin does? it's an input signal for U1_RF.
I created a new pad. Will try this afternoon to solder back a new wifi chip.

b.t.w. i noticed that the scheme is not correct for U1_RF. They numbered the pad's wrong. all pad numbers should move 1 position CCW. (wites om tesla document)

I will write back if this solved the problem.

br
Maurice

dutch_anykey · 12-01-2014, 23:10

No luck yet.

Didnt have much time to tinkle, busy at work at the moment.
But I only have a batch "original" Wifi bga's (USI 339xxxxx)
I think these are crap. Haven't had many luck with these chips. Maybe they are too temperature sensetive. I should have bought the high temperature resistant chips.

I have spinning bluetooth wheel and wifi greyed out. Maybe it is destroyed already when soldering it on. although i did it carefully with pre-heater and tried to put minimum heat in the chip itself.

Maybe you can confirm that these chips are very heat sensetive?
And spinning bluethooth wheel and grey wifi points to a fried wifi chip?

Hopefully this weekend i have some time to measure some voltages and components related to wifi.

kind regards,
Maurice

TSmobile_CS3 · 12-02-2014, 00:18

Welcome ! iphone 4s with schematic you . you should rely on the schematic to defined parameters , indicators The electric bulbs or faulty . schematic to determine the cause of it . and then offer solutions . Wish you success !

11-27-2014, 16:29	#1 (permalink)
dutch_anykey Junior Member Join Date: Jun 2014 Posts: 13 Member: 2197917 Status: Offline Thanks Meter: 0	iphone 4s wifi need help troubleshooting. hi, Strange thing with iphone 4s wifi problem. Fixed several 4s phones already by exchanging wifi chip. Now I have on that is making some trouble. put new chip on it already 3 times. on startup greyed out wifi slider problem remains, no wifi hardware adress. When i start uo and firmly hold my finger on the wifi chip, it comes up and works. I know first thing you would say is bad soldered chip. But on last solder i made sure all the black glue was gone. And when flowing started i could see the chip slide on its place. 99% sure that the wifi chip is soldered well on it. maybe a pad lost connection to its underlying layer? Also i lost R49_RF and C13_RF. I directly jumpered the output to the coil L1_RF. Like I said when i apply pressure to the wifi chip, everything is working. Seems tat it is not missing the RC combination. (Iwill solder them back with components from another phone) Can someone tell me what the fuction of C13_RF is? And strange that R49_RF is 0 ohms value. Could it be related to my problem? kind regards

11-28-2014, 00:50	#2 (permalink)
arvaser Freak Poster Join Date: Jun 2013 Posts: 178 Member: 1952487 Status: Offline Thanks Meter: 43	hello, remove it and check with tweezers that all pads are connected. also maybe there is a problem with the PCB that causes this problem. friend of mine told me that he got iphone 5c without IMEI, he reballed the baseband and it was still the same. but when he pressed the ic it got imei back.. so sometimes it might be problem with the PCB.

11-28-2014, 08:46	#3 (permalink)
dutch_anykey Junior Member Join Date: Jun 2014 Posts: 13 Member: 2197917 Status: Offline Thanks Meter: 0	Hi arvaser, Thanks for the reply. I desoldered the chip again and checked the pads. Pin 10 > "HOST_WLAN_HSIC_RDY" is crooked. Maybe you know what this pin does? it's an input signal for U1_RF. I created a new pad. Will try this afternoon to solder back a new wifi chip. b.t.w. i noticed that the scheme is not correct for U1_RF. They numbered the pad's wrong. all pad numbers should move 1 position CCW. (wites om tesla document) I will write back if this solved the problem. br Maurice

12-01-2014, 23:10	#4 (permalink)
dutch_anykey Junior Member Join Date: Jun 2014 Posts: 13 Member: 2197917 Status: Offline Thanks Meter: 0	No luck yet. Didnt have much time to tinkle, busy at work at the moment. But I only have a batch "original" Wifi bga's (USI 339xxxxx) I think these are crap. Haven't had many luck with these chips. Maybe they are too temperature sensetive. I should have bought the high temperature resistant chips. I have spinning bluetooth wheel and wifi greyed out. Maybe it is destroyed already when soldering it on. although i did it carefully with pre-heater and tried to put minimum heat in the chip itself. Maybe you can confirm that these chips are very heat sensetive? And spinning bluethooth wheel and grey wifi points to a fried wifi chip? Hopefully this weekend i have some time to measure some voltages and components related to wifi. kind regards, Maurice

12-02-2014, 00:18	#5 (permalink)
TSmobile_CS3 Junior Member Join Date: Aug 2014 Posts: 1 Member: 2233990 Status: Offline Thanks Meter: 0	Welcome ! iphone 4s with schematic you . you should rely on the schematic to defined parameters , indicators The electric bulbs or faulty . schematic to determine the cause of it . and then offer solutions . Wish you success !