Memory; The Reference For No- Power On Mobile - FLY IQ442 QUAD Maintenance Work Manual

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2.3 Memory

SDRAM + NAND Flash Memory save the program code and run the program. If they have some

any problems, the system will not boot up or the system can't download the system's program

code.

This part's circuit is relatively simple, if the memory has something wrong , we should check the

SMT's problem first. IF not the SMT's problem, we should check the memory's supply

voltages .Such as the voltage on C210/206/C219/C220/C221 should be 1.8V，voltage on

C222/C223/C224 should be 1.2V, the voltage on C214/C215 should be 0.6V. There should be a

clock signal through the resistor R212.

NOTES: there are some cases that AP or BP com port cannot be recognized by PC, the code can't

be downloaded, it can be shorted TP1520 (or R214) to GND, power on again, the com port can

be founded.

From diagram 13, the power supply 1.8V, 1.2V and 0.6V are memory power; if the U204 or

U203 is not well SMT, the power supply cannot be output, the software can't be

downloaded.

1. The Power ON key is pressed, checking the power current is changed, the USB is recognized

by PC, please check the LCM display, checking the connection of LCM connector.

2. If the power current is always 30—70ma，the USB port can't be recognized by PC, please

check the Memory first, and the PMU output voltage, the CPU is the final checking.

3. The power current is too high when the power-on key is pressed, and decreased to 0ma,

please check short-circuit, check the PMU output voltages, and find out which one is

shorted.

4. The Power ON/OFF frequency, please check the software issue, or the battery is lower

voltage.

5. The display is frozen after the power on, please check the Memory or the software issue,

Diagram 12 DC-DC output for CPU core2

Diagram 13 Memory power

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