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Apple's top-of-the-line smartphone for 2021. Released September 24th, the iPhone 13 Pro Max sports a 6.7" ProMotion OLED display, a new triple rear camera system, and 5G connectivity. Successor to the iPhone 12 Pro Max.

Cellular front end diagnostic

How do you guys go about diagnosing Cellular front end issues on iPhone? I’ve replaced the charging flex on two iPhones recently and they end up failing the Apple diagnostics after. Cellular appears to be fine and working. The replacement flex is OEM pull. It appears to be working correctly as it all passed the diagnostic except for the Cellular test. Is there anything specific I should look for? I cleaned and checked all the grounding contact points on the screen/frame and the pins themselves and they looked fine. The only repair this 13 Pro Max had was a charging port replacement. I only removed the lower components needed to do the replacement so Im not really sure what went wrong.

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Molded within the case are the antennas which are accessed by the cellular front-end logic via screws and bus bars. Make sure you have a good electrical connection between the Antenna point and the logic board. Any corrosion, tarnish or physical damage can prevent good connection to your cellular provider.

To see the signal strength I just use the codes as listed here All iPhone Secret Codes

*#3001#12345#*

Use a second phone accessing the same carriers network at the same location to gage if your connection is good.

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