FLY DS186 Operating and maintenance instructions

DS186_Maintenance
Instruction
Prepared by：xiaoyu wan
Approved by：
Date：2010.9.25

TABLE OF CONTENTS
1 Overview DS186
1.1 About DS186 Phone
1.2 Distribution of the mainboard components
2 RF
2.1 RF Overview
2.2 Transmit
2.3 Receive
2.4 Common RF Malfunction
3 Baseband
3.1 Baseband Overview
3.2 Logic
3.3 Power management
3.4 Baseband common malfunction
4 Reference for maintenance
4.1 No power on
4.2 Shut off automatically
4.3 Dead halt
4.4 No charge
4.5 Quantity of electricity faulty detection
4.6 No display
4.7 LED NG (on the LCD)
4.8 LED NG (on the keyboard)
4.9 Key NG
4.10 No ring
4.11 No receiving voice
4.12 No sending voice or voice is small
4.13 No vibration
4.14 SIM card inefficacy
4.15 TF card inefficacy
4.16 Camera inefficacy
4.17 Bluetooth inefficacy
4.18 Earphone inefficacy
4.19 FM inefficacy

1 Overview DS186
1.1 About DS186 Phone
DS186 mainboard is based on the MTK platform designed to support 2-
band which supporting the FM and Bluetooth calls and transmission, the
mainboard system consists of the base-band （CPU：
MT6253+TY6701111184KC）and the RF (MT6253+SKY77518).

Flash
CPU
Audio PA
BT area
RF PA
LED Driver
FM
LCD
K/B FPC
MT6253
MT6612
TY6701111184KC
SKY77518 RDA5802ES
1.2 Distribution of the mainboard components

Antenna
Socket of SIM card
and TF card
Battery CONN
Earphone CONN
Adapter CONN
Camera FPC

2 RF
2.1 RF Overview
RF part mainly consists of transceiver MT6253 (adopts program of near-zero IF
receiver, supporting the EGSM / DCS and 26M VCTCXO as the clock input,
integrated clock buffer, LO VCO and TX VCO and regulator, only need for
external connections of VBAT / AVDD), SKY77518 (it supports EGSM / DCS
and integrated automatic power control and transceiver switch).
Transceiver (MT6253) with the RF modulation and demodulation functions
contains IF frequency synthesizer and VCO RF, which is part of the core
component of the RF. PA has a major role in amplification of modulation
signal, and it must be controllable and the speed should meet the GSM
agreement.

2.2 Transmit
TX is composed of the modulation loop, power amplifier and antenna
switch. PLL is mainly in the internal MT6253, I / Q signal first
enters into the MT6253, after entering the PLL the signal is
modulated to RF, and then it outputs from the chip to PA, converts
into electromagnetic energy through antenna by the antenna
switch after enlarged.
PA:
This part adopts voltage control to achieve and its role is to amplify
the signal power in accordance with the requirements. It is divided
to two different power levels through VRAMP signal. The transmit
signal of GSM is 5 to 19, power is from 3.2MW to 2W while DCS is
0 ~ 15, power from 1MW ~ 1W. PA is time-sharing work controlled
by TX-EN chip, the output power of PA is controlled by VRAMP
(APC) through the voltage. PA is intermittent work, by the BS to
achieve the choice of frequency bands.
2.3 Receive
Antenna RX - MT6253 (RX_VCO mixer) - band-pass - Amplification -
filter - Amplification - RX_VCO mixer - CPU

2.4 Common RF Malfunction
Detection and Maintenance Flow Chart of MS Transmit malfunctio

3 Baseband
3.1 Baseband Overview
DS186 Baseband consists of CPU MT6253 and Program Memory. MT6253
baseband, the core device of the mainboard, is responsible for the normal work
among various parts of mainboard, such as voice processing, image processing,
power management as well as MS communications.
MT6253 digital baseband contains ARM7EJ-S 32-bit core and 144Kbyte SRAM.
MT6253 which is an enhanced GSM Processor integrated Channel Codec
subsystems interiorly including Channel Codec, Intertlace / Deinterleave,
Encryption / Decryption and Control Processor subsystems including ARM7EJ-S
and its peripheral circuits. There are 25 address lines,16 data lines, 8 chip select
lines, provided 7 external interrupt Interface, 52M/104M operation clock.
Analog baseband contains MT6253 analog baseband chip, audio, baseband
codec and power management. Four major functional blocks integrated internal:
Audio codec including Voice input / Output channel, Buzzer output; Baseband
codec including Differential I, Q input / output, GMSK modulation and A / D, D / A;
Auxiliary parts including AFC DAC, RAMP DAC, AGC DAC and a seven-channel
A / D. And WATCHDOG interface is set internal to enhance the stability of the
system.

3.2 Logic
Logic part is composed of MTK base-band management chip MT6253, power
management chip MT6253 and Nor Flash.
CPU ：MT6253
Nor Flash：TY6701111184KC
PMU ：MT6253
3.3 Power management
Power management consists of the charging circuit integrated in MT6253 and the
external charging circuit. It provides 11 road LDO voltage. Besides, it completes
the logic level conversion of SIM card. The chip also outputs the system reset
signal.

Boot process:
The normal boot is to press boot key which is that the PWRKEY is being dragged down.
Once the boot key is pressed, all LDO are open except VSIM. After VCORE opening RESET
timer and timer out, RESET is being pitched up to start the digital baseband chip, that is,
UMT6253 starts to run and roll polling its ROWX pin, pitch up its PWRONIN pin, then you can
release the boot key. This is the initial boot process.

3.4 Baseband common malfunction
3.4.1 Nor 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.

3.4.2 Detection and Maintenance Flow Chart of No download malfunction

4.1 No power on No power on
Check whether the
battery voltage is
higher than 3.4V
Check whether the battery
and the key pad is
oxidized or there is
anything else on it
Charge the battery
Wipe off the thing
or clean the key pad
Check whether the
connection of KEY PCB &
MB is OK
Reassemble or Charge
the KEYPAD FPC
Take out the LCD and
SPK, Check whether it is
powered on
Cross-testing the
LCD&SPK,
Change the defective
Y
N
Y
N
N
N
Y
Y
4 Reference for maintenance

Check whether
R4401，R1107 is
broken Change R4401,R1107
Replace the earthed capacitor
corresponding to the
defective pin, Check whether
it is OK
ChangeU1100
C1119:1.8V
C1119:2.8V,
C1120:2.8V,
C1121:2.8V,
C1122:2.8V,
C1123:2.8V,
Y
N
NN
Connect with the battery,
press “ON” key, check
whether the output voltage
of U1100 is normal
Y
Check whether the output
frequency of X1100 is 32.768K ChangeX1100， C1100，C1101
N
Y

Change the Flash (U1101),
check whether it is OK
ChangeU1100
OK
Y
Check whether the output voltage
of U2602 pin 3 is 0.5V around Change U2602 Change U2605
N
Y
N
Change U1101
N

4.2 Shut off automatically
Shut off automatically
D/L the latest software,
Check whether it is OK
Replace with a
good battery, Check
whether the
primary cell is broken
ok
Change the battery
Check whether the
rubber, used to fix the
battery, is lost or at the
other location
Reassemble the
rubber
Check whether the battery
and the Connector of J9410 is
oxidized or there is
anything else on them
Wipe off the thing
or clean the Connector
N
N
N
N
Y
Y
Y
Y