Micromax X377 User manual

X377 L3 Service Manual
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A) Technical Specifications:
Particular
Remarks
Key Matrix For Flashing
N/A
Chipset
SC6531E
Android Version
NA
Frequency
900/1800mHz
Network Mode
GSM
Rom
32Mbit
RAM
32Mbit
Internal SD Card memory
NA
Expandable Memory
Support up 16 GB T card
Factory mode code
*#2020#
Good Earpiece volume
97Hz
Good Loudspeaker volume
89.5dB
Good MIC volume
-42db
Good Vibrator volume
170Hz
Engineering Code
*#346#

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MENU
目录
1 Main board explored overview..............................................................................................................3
2.1 Can’t download...................................................................................................................................5
2.2 Can’t power on................................................................................................................................... 6
2.3 Can’t getting charged......................................................................................................................... 7
2.4 LCD Display fail....................................................................................................................................8
2.5 Camera is not working........................................................................................................................9
2.6 RECEIVER is not working...................................................................................................................10
2.7 SPEAKER is not working.................................................................................................................... 11
2.8 MICPHONE is not working................................................................................................................ 12
2.9 VIBRATOR is not working..................................................................................................................13
2.10 FM is not working........................................................................................................................... 14
2.11 BT.................................................................................................................................................... 15
2.12 Can’t detect the SIM CARD............................................................................................................. 17
2.13 Can’t detect the TF CARD............................................................................................................... 18
2.14 RF Module................................................................................................................................... 19

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1 Main board explored overview
Figure --top
LCM
Power key

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TORCH 1 TORCH 2
SPEAKER
VIBRATOR
SIM2
SIM1
T/F SLOT
Charger
MOSFET
CPU RF PA
Battery
connector
BT Antenna
26MHz
Crystal
MIC
Figure—bottom
I/O
FM
Antenna
3.5 Phone
JACK
GSM
Antenna

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2.1 Can’t download
It might be the poor soldering of IO Connector, please check the soldering quality of IO Connector first,
and then check the related diagram.
Solution：
1. Use a fresh data cable.
2. Check the I/O connector and its soldering quality, and then check the volume ofJ0802.
3. Re-Solder the IO connector.
4. Re-Solder the 26M crystal (X0601) or change it.
5. Re-Solder the CPU (U0100) or change it.
Figure--BB IC D/L interface
Figure--USB I/O interface
Figure--26M crystal

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2.2 Can’t power on
Solution：
1. Check resistor R0999 from net PWRKEY to net PBINT is correct ornot.
2. Power on the handset with DC to verify its current is correct or not, check the diagram of VBAT &VBUS
is shorted or damaged.
3. Re-Solder the 26M crystal (X0601) or change it.
4. Re-Solder the CPU (U0100) or change it.
Figure--Powerkey circuit

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X377 L3 Service Manual
2.3 Can’t getting charged
Solution：
1. Use a fresh USB data cable or charger, re-solder the IO connector.
2. Check T0391 is poor soldering, shorted or damaged.
3. Check Mid PIN of battery connector is poor soldering or not ,check the related component is shorted
,broken or not (J0392 might be broken, T0398might be shorted).
4. Re-Solder the CPU (U0100)or change it.

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2.4 LCD Display fail
Solution：
1. Re-Solder the LCD or change it.
2. Re-Solder the CPU (U0100)or change
it.
Figure – LCD circuit

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2.5 Camera is not working
Solution：
1. Re-Solder the camera or change it.
2. Re-Solder the CPU(U0100)or change it.
Figure – Camera circuit

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2.6 RECEIVER is not working
Solution：
1. Assembly the receiver or change it.
2. Check the receiver circuit verify it is shorted with grounding or
not(B0547/B0548/B0557/B0558/R0557/R0558/C0547/C0548/C0549/).
3. Re-Solder the CPU U0100 or change it.
4. Figure--Receiver circuit

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2.7 SPEAKER is not working
Solution：
1. Assembly the speaker or change it.
2. Check the speaker circuit verify it is shorted with grounding or
not(B0547/B0548/C0541/C0542/C0547/C0548/C0549).
3. Re-Solder the CPU U0100 or change it.
Figure -- Speaker circuit

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2.8 MICPHONE is not working
Solution：
1. Assembly the micphone or change it.
2. Check the micphone circuit soldering quality
(R0501/R0502/R0503/R0504/R0505/C0500/C0501/C0502/C0503/C0504/C0507/C0508/C0509/
B0501/B0502/B0507/B0508).
3. Re-Solder the CPU U0100 or change it.
Figure -- Micphone circuit

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2.9 VIBRATOR is not working
Solution：
1. Assembly the vibrator or change it.
2. Check the vibrator circuit soldering quality (D0531/C0531).
3. Re-Solder the CPU U0100 or change it.
Figure – Vibrator circuit

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2.10 FM is not working
Solution：
1. Check phone jack (J0881).
2. Check the FM circuit (built-in) soldering quality (R0137/C0137/L0137/R0138/R0881/L0881/T0881).
3. Re-Solder the CPU U0100 or change it.
Figure -- FM circuit (built-in)

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2.11 BT
Solution：
1. Check BT antenna connection.
2. Check the BT circuit soldering quality (R0134/C0134/L0134/R1130/R1139/L1139/L1138).
3. Re-Solder the CPU U0100 or change it.
Figure -- BT circuit
2.12 Can’t detect the SIM CARD
Solution：
1. Check the connection of SIM card or change a fresh SIM card to verify it.
2. Check soldering quality of the SIM connector (J0831/J0841)
3. Check the SIM diagram to verify whether component is shorted with grounding, the component missed
or broken.
4. Re-Solder the CPU(U0100)or change it.

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Figure – SIM Card circuit
2.13 Can’t detect the TF CARD
Solution：
1. Check the connection of TF card or change a fresh TF card to verify it.
2. Check the soldering quality of TF slot (J0851).
3. Check the TF diagram to verify whether component is shorted with grounding, the component missed
or broken.
4. Re-Solder the CPU(U0100)or change it.
Figure – TF circuit

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2.14 RF Module
Solution：
1. Flash the SW.
2. Check the GSM antenna connection.
3. If there was no signal, then re-solder or change the RF PA(U0601).
4. Re-solder the CPU (U0100) or change it

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Figure -- RF Front-end Module