iFixit has recently posted that Apple may have silently started fixing the iPhone 4′s antenna issue the so called ‘Deatch Grip’. According to them :
“??Reports started surfacing today that Apple may have quietly revised the iPhone 4 to add a nonconductive coating to the metal band on the sides of the phone. This would fix the sudden signal drop from electrically bridging the antennas by touching the band in the bottom-left corner with your hand.”
The serial number on the unit tells you the manufacture date; the original iPhone 4 was manufactured in mid-June (week 25). The replacement unit that is being shipped by Apple now (early-July, week 27) may not have the issue, even though it is too early for a manufacturing change.
The iPhone 4 serial number is easy to decode! It’s in this format:
aabccdddeef
aa = Factory and Machine ID
b = Year
cc = Production Week
ddd = Unique Identifier
ee = Colour
f = size
iFixit serial numbers:
85025xxxA4S (16GB unit they took apart)
86025xxxA4T (32GB test unit)
86027xxxA4T (32GB replacement)
If you got an iPhone in the last few days, check the serial number. If the production week is bigger than 27, try checking the impedance of the metal frame with a multimeter. If you hold the leads about an inch apart, the resistance should be less than one ohm. If it’s substantially higher, you may have a unit with the new coating. (Accuracy of multimeters varies dramatically, but we’d expect a nonconductive coating to have a very high impedance.)
