FLY EZZY, Service Manual

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4.1.9 Cannot download software
There are many reasons that can lead to download failure, but the problem of the analog switch IC,
Which is used to control the dual-used port by headset and UART, is the most common? So you need to
Pay more attention to it.
4.2 Analysis of RF failure
RF failure often occurs in calibration or capability test, the best diagnostic method is to use
Wireless universal tester, spectrum analyzer and signal source matched with META tool to test it.
Corresponding components with the RF receiving mainly are: antenna switch saw filters,
matching circuit etc. You need to check if one of them is bad soldering or damaged. If power received
is too low maybe the RF circuit is cut off, you need to check saw filter, matching circuit, and antenna
Switch and control signal etc. If the bit error is too high, it may be because the saw filter is not
Qualified.
RF transmitting circuit associated components is mainly as below: base band MT6223A, RF
Transceiver AD6548, attenuator, RF PA, antenna switch etc, main test items including power value,
power vs. time, modulation and switch spectrum etc. The current consumption when transmitting RF
signal is about 200 mA. So if the current is too low, it means the PA doesn’t work properly, you need
to change it for a new one.