Dual Sim - Dual Standby Single Phone; Atv Circuit; Baseband Common Malfunction - FLY E195 Service Menu

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3.5 Dual SIM – Dual Standby Single Phone

Dual SIM – Dual standby single phone is based on the GSM agreement, in standby mode,

communicate between mobile phones and base station with shaking hands. Because this

communication has the time gap, so we can switch two SIM to shake hands and performs

a set of system of double user SIM standby effect through the high speed. But when one

is calling, the other is forced to disconnect. After finishing the call, it will return to the dual

SIM – dual standby status.

The phone supports ATV function.

3.7.1 OR Flash programming does not download

Data lines used for downloading software: VBAT, TX, RX, GND, CHARGE. It is mostly due

to the false solder and wire bonding. First check whether the serial port of PC and cell

phone is unrestricted, if not, it is caused by being lack of devices or empty solder of power

manager, USB-con and peripheral resistance. Measure the TX, RX signals by using

AC-coupled oscilloscope to track the signal flow, if a certain period circuit of no signal it

may be AC short circuit to ground, or is caused by a short circuit and open circuit. On

checking the malfunctions, first should carefully observed the welding of these devices

with a magnifying glass, then plug in the download line to observe whether the current is

normal, there is short-circuit to ground of VCHG or VBAT if the current is large, at this time

cut off power supply as soon as possible, and then find the short-circuit point. It may be

the abnormal output power supply of a certain circuit that the current is larger than normal

(about 30 mA) but not particularly large, at this time should check whethe the valgate of

VCORE (1.8V), VDD (2.8V), VADD (2.8 V), VTCXO (2.8V), VRTC (1.5V), VMEM (2.8V) is

noamal, if not, bad welding can be detected. Focus on checking the welding of PMU and

USB-CON if there is a little or no current. Unplug and re-plug the download line to see if it

is caused by poor contact; It can test that whether the output of 26MHz clock signal to the

CPU is normal by using oscilloscope.

3.7.2 Detection and Maintenance Flow Chart of No download

malfunction

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