Trouble Shooting
iPhone 7 Vibration Not Working when we play a ringtone or some other relevant action.
Trouble Shooting
Replace another vibrator to test first, but the issue still unresolved. And continue to check the motherboard, there is no deformation or corrosion, the appearance is good.
Then check the relevant pins on dock connector J4101, diode values on pin 40 and 42 are normal, continue to measure the small components connected with the vibrating chip U3502, all the diode values are normal.
Then we checked the voltage on C3534 and C2114, which are the power supplies to U3502, both of them were normal. Judging by this, the faulty is probably related to U3502.
Then replace U3502 with a new one and test it, the problem resolved.