iPhone 6s mobile phone Start Hang Logo(white apple)and restart maintenance

Machine model: iPhone 6s

Malfunction: Hang Logo(white apple)restarts after starting.

Maintenance process: an iPhone 6s water damage machine. The customer repaired it outside once but failed to fix it. Bring it to me, and the Hang Logo(white apple)status will restart occasionally. The USB management chip and the charging tube were repaired and replaced before the board was removed for inspection. From the traces of moving the motherboard, it can be seen that the last repair manual was not very good, and there were some small solder beads around the chip, which was a serious mistake for maintenance.

Clean up the motherboard and replace the new USB management chip and charging tube again, and the effect is still the same.Hang Logo(white apple)is restarted intermittently, the test battery detects pin Diode value is normal, and the boot conditions Diode value is normal and VCC are normal. There are few cases of water damage system damage. After discussing with customers, Update System can be carried out, and the computer can be tested online. If the computer jumps out of the unrecognized USB, guess that the problem may appear on USB management chip line. Take USB management chip and test diode value.

iPhone 6s mobile phone Start Hang Logo(white apple)restart maintenance Figure 1.

It is measured that USB management chip chip F4 pin PP3.0V_TRISTAR is in Short circuit state. This point is connected WiFi a power supply and a U5411_RF receiving amplifier connected to the head of the motherboard by Inductor FL5408_RF. In order to find out exactly where the problem lies, first remove FL5408_RF, and test both ends of Inductor to find that the amplifier end belongs to.

iPhone 6s mobile phone Start Hang Logo(white apple)restart maintenance Figure 2.

The two Capacitor on the removed side are still the same, and the Short circuit can’t be measured by directly removing U5411 chip.

iPhone 6s mobile phone Start Hang Logo(white apple)restart maintenance Figure 3.

The glue around this chip is particularly soft, which can be removed at 150 degrees. Try not to remove Capacitor with the edge. The upper left corner is the origin. Pay attention to the direction when loading. After the IC is installed, fill in FL5408_RF test and start up normally. By the end of this maintenance.