Which parts on bad ESN/IMEI phone can be used?

NoSole

macrumors newbie
Original poster
Dec 27, 2011
25
0
I get that a phone with a bad ESN/IMEI cannot be activated. My question is, what part(s) is(are) associated with the ESN? Or in other words, if I bought a 5 with a bad ESN for parts, which parts could I use (or rather, which parts could I specifically NOT use)?

This is kinda like the eternal question "Where does the soul lie?", accept less ethereal and more literal with a definitive answer... "Where does the ESN lie?"

My current 5 is on the fritz and I need to replace a few parts, but don't want to pay a dealer or Apple full price for each one. I'd rather buy one off CL/Ebay (with a bad ESN) and just frankenstein the parts into my phone to regain full functionality. If you care to share your thoughts on that subject, you can read and respond to this thread.
 

NoSole

macrumors newbie
Original poster
Dec 27, 2011
25
0
Everything, but the motherboard/logicboard of the device is useful.
Makes sense. If the IMEI lives on the motherboard, then that's the one piece that can't be salvaged for parts... which sucks cuz if my problem is on the motherboard, then buying a phone with a bad ESN won't help.
 

jav6454

macrumors P6
Nov 14, 2007
16,876
1,532
1 Geostationary Tower Plaza
Makes sense. If the IMEI lives on the motherboard, then that's the one piece that can't be salvaged for parts... which sucks cuz if my problem is on the motherboard, then buying a phone with a bad ESN won't help.
You are right and wrong. The IMEI lives in the baseband chip itself; the Qualcomm SoC.

If you can somehow manage to remove that and replace it with a working SoC, then the logic board is useful once again. However, almost all SoC in the iPhone are BGA based, which means a heat gun and lots of patience. Also, large error margins.
 

NoSole

macrumors newbie
Original poster
Dec 27, 2011
25
0
You are right and wrong. The IMEI lives in the baseband chip itself; the Qualcomm SoC.

If you can somehow manage to remove that and replace it with a working SoC, then the logic board is useful once again. However, almost all SoC in the iPhone are BGA based, which means a heat gun and lots of patience. Also, large error margins.
Yeah. I'm fairly confident in my skills, but only on an amateur level (i.e. screws, glues, and pop connectors), so I wouldn't feel comfortable to getting into solders and heat guns and stuff. I could probably do it, but there's too much at stake.

If I were to consider giving it a shot, could you direct me to a tutorial? Or at least schematics so I can see how it fits together?

As a secondary concern, I would also need to swap the memory as well. I have a 64gb, but would want to buy a 16gb to keep the cost lower.
 

jav6454

macrumors P6
Nov 14, 2007
16,876
1,532
1 Geostationary Tower Plaza
There is more science to this than just go at it. First and foremost the Qualcomm chip might have specific soldering guidelines (ie. number and size of solder balls).

Furthermore you'll have to consider the component on the other side of the logic board will also suffer from the heat (as well as any other side components). So being very precise is very paramount. Not to mention, the polarity of the chip when soldering.

It is not a process I would recommend to anyone. At least without the help of detailing heat gun and a proper reflow oven.
 

NoSole

macrumors newbie
Original poster
Dec 27, 2011
25
0
There is more science to this than just go at it. First and foremost the Qualcomm chip might have specific soldering guidelines (ie. number and size of solder balls).

Furthermore you'll have to consider the component on the other side of the logic board will also suffer from the heat (as well as any other side components). So being very precise is very paramount. Not to mention, the polarity of the chip when soldering.

It is not a process I would recommend to anyone. At least without the help of detailing heat gun and a proper reflow oven.
Yep, I'm out.
 

Charadis

macrumors 6502a
Jul 3, 2010
929
129
There is more science to this than just go at it. First and foremost the Qualcomm chip might have specific soldering guidelines (ie. number and size of solder balls).

Furthermore you'll have to consider the component on the other side of the logic board will also suffer from the heat (as well as any other side components). So being very precise is very paramount. Not to mention, the polarity of the chip when soldering.

It is not a process I would recommend to anyone. At least without the help of detailing heat gun and a proper reflow oven.
There should be a reference point on the chip, like a notch in the grid, that directs the technician on the proper placement of the chip on the board. The pin outs are the same for every chip of the specific part number; changes will be detailed in the errata. In a proper reflow, all the solder balls on a new chip, or a properly reballed used one, should align exactly to each assigned pad on the board. This may require a bit of eyeballing and patience! DIY reballers should find stencils made for the specific chip of interest and appropriate sized solder balls and flux.

When using a heat gun as opposed to an infrared reflow station, it is recommended to equip a nozzle that fits as closely to the dimension of the chip being reflowed.

Proceed at your own risk. :) Sent from my iPad.
 

charlituna

macrumors G3
Jun 11, 2008
9,631
815
Los Angeles, CA
You would probably be better off finding a phone that can be activated but perhaps needs a new screen and taking your good one off the phone with the bad esn.

Or selling that phone to someone who wants to do just that and is willing to pay you for the 'parts'

Back Camera, screen, speaker, microphone, home button internals, receiver, battery and vibe motor should all be reusable in an iPhone 5
 

jav6454

macrumors P6
Nov 14, 2007
16,876
1,532
1 Geostationary Tower Plaza
There should be a reference point on the chip, like a notch in the grid, that directs the technician on the proper placement of the chip on the board. The pin outs are the same for every chip of the specific part number; changes will be detailed in the errata. In a proper reflow, all the solder balls on a new chip, or a properly reballed used one, should align exactly to each assigned pad on the board. This may require a bit of eyeballing and patience! DIY reballers should find stencils made for the specific chip of interest and appropriate sized solder balls and flux.

When using a heat gun as opposed to an infrared reflow station, it is recommended to equip a nozzle that fits as closely to the dimension of the chip being reflowed.

Proceed at your own risk. :) Sent from my iPad.
Exactly. Also, bear in mind, the stencil for this process is going to be expensive since you require one that takes into account components already placed. Reballing a dense BGA is very complicated.

Yes, the nudge or printed mark should tell anyone which is the orientation of the chip.
 
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