LG LG-200 User manual

LG-200
SERVICE MANUAL
SERVICE MANUAL MODEL : LG-200

- 1 -
1. PERFORMANCE ..................................................... 2
1-1. HW Features ........................................................... 2
1-2. Memory Requirment ............................................... 2
1.3. Technical Specification ........................................... 3
1-4. GSM band RF Specifications ................................. 7
1-5. DCS band RF Specifications .................................. 8
1-6. Receiver (GSM) ...................................................... 9
1-7. Receiver (DCS) ...................................................... 9
2. TECHNICAL BRIEF .............................................. 10
2-1. Receiver ............................................................... 10
2-2. Transmitter ........................................................... 14
2-3. The PA Circuit and its Control .............................. 17
2-4. 13 MHz Clock ....................................................... 18
2-5. Main Processor and DSP ..................................... 19
2-6. Power Supplies and Control Signals .................... 21
2-7. User Interface Board ............................................ 28
2-8. Testing Set-up and Checking Signals .................. 32
2-9. Dimensions of Main Components. ........................ 43
3. TROUBLE SHOOTING ....................................... 53
3-1. Power Supply Failure ........................................... 53
3-2. Voice Function Failure .......................................... 55
3-3. Display Function Failure........................................ 55
3-4. Transmission & Receiving Failure ........................ 57
3-5. Other Function Failure........................................... 57
4. TEST POINT DATA ............................................... 60
5. ASSEMBLY INSTRUCTIONS ........................... 68
6. BLOCK DIAGRAM ............................................... 73
7. CIRCUIT DIAGRAM ............................................. 74
8. HOW TO DOWNLOAD S/W .............................. 83
9. HOW TO PROCESS CALIBRATION............... 84
10. EXPLODED VIEW .............................................. 90
11. REPLACEMENT PARTS LIST......................... 91
Table Of Contents

- 2 -
1. PERFORMANCE
1-1. HW Features
1-2. Memory Requirment
Item Feature Comment
Battery Li-Ion Battery, 600mAh
Size : 105.9x44.8x19.7mm
Weight : 89g, 77cc
PCB : M/B:99.5x38.3;K/B:99.5x39.4mm
AVG TCVR current(mA) GSM Imax(390mA),DCS Imax(320mA)
Stand by current(mA) ≤5mA
- Talk time 2.5-hour (GSM Tx Level_7)
- Stand by time 85-hour(Paging Period:2 RSSI:-85dBm)
- Charging time 1.5-hour
RX sensitivity GSM:-107dBm, DCS:-104dBm
TX output power GSM (Level 5:33dBm), DCS (Level0: 30dBm)
GPRS compatibility N/A
SIM card type 3v/5v small
Display 128x64
Status Indicator Soft Icons
Keypad : 0-9, #, *, C, P/book, up/down, on/off
ANT External
System connector : N/A
Ear Phone Jack Yes
PC synchronization N/A
Memory : 1MB
Speech coding EFR/FR
Data & Fax N/A
Vibrator Yes
Melody(for Buzzer Function) 22
Voice Recording N/A
C-Mike N/A
Receiver Yes
Speaker Phone N/A
Portable Handsfree Yes, option
Travel Adapter Yes Switching
Options
Application RAM Size ROM Size
GSM Protocol 120KB 880KB
WAP (AUR Browser) N/A N/A
Zi ezText (2 Languages at N/A N/A
the same time)
ART N/A N/A
Voice Memo (3 Minutes) N/A N/A
Phone Book 1KB 2KB
Voice Tag N/A N/A
Game & Accessory 3K 20K
GPRS N/A N/A

1. PERFORMANCE
- 3 -
Item Description Specification
1 Frequency Band GSM900 band
Tx : 890 + n*0.2 MHz
Rx : 935 + n*0.2 MHz
(n = 1 ~ 124)
GSM1800 band
Tx : 1710 + (n-512)*0.2
Rx : 1805 + (n-512)*0.2
(n = 512 ~ 885)
2 Phase error RMS < 5 degrees
Peak < 20 degrees
3 Frequency error < 0.1ppm : = 90 Hz (for GSM900) or 180 Hz (for GSM1800)
5 Power Level GSM900
Control Level Power Level Tolerance
5 33 dBm ± 2dB
6 31 dBm ± 3dB
7 29 dBm ± 3dB
8 27 dBm ± 3dB
9 25 dBm ± 3dB
10 23 dBm ± 3dB
11 21 dBm ± 3dB
12 19 dBm ± 3dB
13 17 dBm ± 3dB
14 15 dBm ± 3dB
15 13 dBm ± 3dB
16 11 dBm ± 5dB
17 9 dBm ± 5dB
18 7 dBm ± 5dB
19 5 dBm ± 5dB
GSM1800
Control Level Power Level Tolerance
0 30 dBm 2dB
1 28 dBm ± 3dB
2 26 dBm ± 3dB
3 24 dBm ± 3dB
4 22 dBm ± 3dB
5 20 dBm ± 3dB
6 18 dBm ± 3dB
7 16 dBm ± 3dB
8 14 dBm ± 3dB
9 12 dBm ± 4dB
10 10 dBm ± 4dB
11 8 dBm ± 4dB
12 6 dBm ± 4dB
13 4 dBm ± 4dB
14 2 dBm ± 5dB
15 0 dBm ± 5dB
1-3. Technical Specification

- 4 -
Item Description Specification
6 Spectrum due GSM900
to modulation Offset from Carrier(KHz). Max. dBc
100 +0.5
200 -30
250 -33
400 -60
600 ~ <1200 -60
1200 ~ <1800 -60
1800 ~ <3000 -63
3000 ~ <6000 -65
≥6000 -71
GSM1800
Offset from Carrier(KHz). Max. dBc
100 +0.5
200 -30
250 -33
400 -60
600 ~ <1200 -60
1200 ~ <1800 -60
1800 ~ <3000 -65
3000 ~ <6000 -65
≥6000 -73
7 Spectrum due to GSM900
switching transient Offset from Carrier(KHz). Max. dBc(KHz).
400 -19
600 -21
1200 -21
1800 -24
GSM1800
Offset from Carrier(KHz). Max. dBc
400 -22
600 -24
1200 -24
1800 -27
8 Spurious emissions Conduction, Emission Status, Appendix 1
Conduction, Emission Status, Appendix 2
9 Bit Error Rate GSM900
BER(Class II) <2.439% @-102dBm
DCS1800
BER(Class II) <2.439% @-100dBm

1. PERFORMANCE
- 5 -
Item Description Specification
10 Rx Level Report accuracy GSM900 GSM1800
≥-88 ≥-86 2 2
≥-101 ≥-99 3 2
< -101 < -99 4 2
11 SLR 8 ± 3 dB
12 Sending Response Frequency (Hz) Max.(dB) Min.(dB)
100 -12 /
200 0 /
300 0 -12
1,000 0 -6
2,000 4 -6
3,000 4 -6
3,400 4 -9
4,000 0 /
13 RLR 2 ± 3 dB
14 Receiving Response Frequency (Hz) Max.(dB) Min.(dB)
100 -12 /
200 0 /
300 2 -7
500 * -5
1,000 0 -5
3,000 2 -5
3,400 2 -10
4,000 2 /
* Mean that Adopt a straight line in between 300Hz& 1,000Hz
to be Max. level in the range.
15 STMR 13 ± 5 dB
16 Stability Margin > 6 dB
17 Distortion dB to ARL (dB) Level Ratio (dB)
-35 17.5
-30 22.5
-20 30.7
-10 33.3
0 33.7
7 31.7
10 25.5
18 Sidetone Distortion Three stage distortion < 10%
19 <Change> System frequency ≤2.5ppm
(13MHz) tolerance
20 <Change>32.768KHz ≤30ppm
tolerance

- 6 -
Item Description Specification
21 Power consumption Full power: < 390mA (GSM) ; < 320mA (DCS)
Standby : 1. Normal ’≤5mA(Mix. power)
2. Using Test mode on DSP Sleep function ≤6mA
22 Talk time GSM/ Level_7 (Battery Capacity 650mA): 130Min
GSM/ Level_7 (Battery Capacity 600mA): 120Min
23 Standby time Under conditions, at least 85 hours:
1. Brand new and full 600mAh battery
2. Full charge, no receive/send and keep GSM in idle mode.
3. Broadcast set off.
4. Signal strength display set at 3 level above.
5. Backlight of phone set off.
24 Ringer Volume At least 70dB under below conditions:
1. Ringer set as ringer 7.
2. Test distance set as 50 cm
25 Charge Voltage Fast Charge: < 600 mA
Slow Charge: < 100 mA
26 Antenna display GSM DCS
≥-84dBm -80dBm : 4
≥-89dBm -85dBm : 3
≥-94dBm -90dBm : 2
≥-101dBm -97dBm : 1
≥-105dBm -101dBm : 0
Tolerance: ± 2 dB
27 Battery indicator Level Voltage (v)
0V≤3.5V
1 3.5 ≤V ≤3.7
2 3.7 ≤V ≤3.8
3 3.8 ≤V ≤4.0
4 4.0 ≤V
Tolerance: ± 0.1V
28 Low Voltage Warning 3.5V ± 0.1V
29 Forced shut down Voltage 3.3V ± 0.1V
30 Battery Type 1 Li-Ion battery
Standard Voltage = 3.7V
Battery full charge voltage =4.2V
Capacity: 650mAh/600mAh (Li-Ion);
31 Travel Charger Linear Charger
In put: 110V or 240 VAC, 50/60Hz
Out put: 5VDC ± 0.25V, 500mA (No Load)
Switching-mode charger
In put: 96- 246VAC, 50/60Hz
Out put: 5VDC ± 0.25V, 500mA (No Load)

1. PERFORMANCE
- 7 -
1-4. GSM band RF Specifications
Frequency Stability < ± 90Hz
RF Maximum Power Output 33dBm
RF Output Power Levels 15, decrementing in 2dB steps
Power Control Level 5 33dBm ± 2dB
Power Control Level 6 31dBm ± 3dB
Power Control Level 7 29dBm ± 3dB
Power Control Level 8 27dBm ± 3dB
Power Control Level 9 25dBm ± 3dB
Power Control Level 10 23dBm ± 3dB
Power Control Level 11 21dBm ± 3dB
Power Control Level 12 19dBm ± 3dB
Power Control Level 13 17dBm ± 3dB
Power Control Level 14 15dBm ± 3dB
Power Control Level 15 13dBm ± 3dB
Power Control Level 16 11dBm ± 5dB
Power Control Level 17 9dBm ± 5dB
Power Control Level 18 7dBm ± 5dB
Power Control Level 19 5dBm ± 5dB
TX Frequency Output
Low Channel (Ch 1) 890.2 MHz
Mid Channel (Ch 62) 902.4 MHz
High Channel (Ch 124) 914.8 MHz
TX Frequency Calculation (Ftx) 890 + (ARFCN x 0.2) = Ftx MHz
TX UHF VCO Frequency
Low Channel (Ch 1) 1160.2 MHz
Mid Channel (Ch 62) 1172.4 MHz
High Channel (Ch 124) 1184.8 MHz
TX UHF VCO Freq. Calculation (Ftuhf) Ftx + 270 = Ftuhf MHz
IF VCO Frequency 540 MHz
TX IF Frequency 270 MHz
Rx IF Frequency 270MHz
Phase Error
Peak Phase Error < 20 degrees
RMS Phase Error < 5 degrees

- 8 -
1-5. DCS band RF Specifications
Frequency Stability < ± 180Hz
RF Maximum Power Output 30dBm
RF Output Power Levels 16, decrementing in 2dB steps
Power Control Level 0 30dBm ± 2dB
Power Control Level 1 28dBm ± 3dB
Power Control Level 2 26dBm ± 3dB
Power Control Level 3 24dBm ± 3dB
Power Control Level 4 22dBm ± 3dB
Power Control Level 5 20dBm ± 3dB
Power Control Level 6 18dBm ± 3dB
Power Control Level 7 16dBm ± 3dB
Power Control Level 8 14dBm ± 4dB
Power Control Level 9 12dBm ± 4dB
Power Control Level 10 10dBm ± 4dB
Power Control Level 11 8dBm ± 4dB
Power Control Level 12 6dBm ± 4dB
Power Control Level 13 4dBm ± 4dB
Power Control Level 14 2dBm ± 5dB
Power Control Level 15 0dBm ± 5dB
TX Frequency Output
Low Channel (Ch 512) 1710.2 MHz
Mid Channel (Ch 699) 1747.6 MHz
High Channel (Ch 885) 1784.8 MHz
TX Frequency Calculation (Ftx) 1710.2 + (ARFCN x 0.2) = Ftx MHz
TX UHF VCO Frequency
Low Channel (Ch 1) 1530.2 MHz
Mid Channel (Ch 62) 1567.6 MHz
High Channel (Ch 124) 1604.8 MHz
TX UHF VCO Freq. Calculation (Ftuhf)Ftx + 180 = Ftuhf MHz
IF VCO Frequency 540 MHz
TX IF Frequency 180 MHz
Rx IF Frequency 270MHz
Phase Error
Peak Phase Error < 20 degrees
RMS Phase Error < 5 degrees

1. PERFORMANCE
- 9 -
1-6. Receiver (GSM)
1-7. Receiver (DCS)
RX Frequency Input
Low Channel (Ch 1) 935.2 MHz
Mid Channel (Ch 62) 947.4 MHz
High Channel (Ch 124) 959.8 MHz
RX Frequency Calculation (Frx) 935 + (ARFCN x 0.2) = Frx MHz
RX UHF VCO Frequency
Low Channel (Ch 1) 1160-1230 MHz
Mid Channel (Ch 62) 1205.2 MHz
High Channel (Ch 124) 1217.4 MHz
RX UHF VCO Freq. Calculation 1229.8 MHz
(Fruhf)F
rx + 270 = Fruhf MHz
RX VCO Frequency 540 MHz
Demodulation Frequency 270 MHz (540/ 2)
IF Frequency 270 MHz
BER (Bit Error Ratio) Type II BER <2.4% at -102dBm
Type II BER <0.1% at -15dBm
RX Frequency Input
Low Channel (Ch 1) 1805.2 MHz
Mid Channel (Ch 62) 1842.6 MHz
High Channel (Ch 124) 1879.8 MHz
RX Frequency Calculation (Frx) Ftx + 95 Mhz = Frx MHz
1535-1610 MHz
RX UHF VCO Frequency
Low Channel (Ch 1) 1535.2MHz
Mid Channel (Ch 62) 1572.6 MHz
High Channel (Ch 124) 1609.8 MHz
RX UHF VCO Freq. Calculation (Fruhf)Frx - 270 = Fruhf MHz
RX VCO Frequency 540 MHz
Demodulation Frequency 270 MHz (540/ 2)
IF Frequency 270 MHz
BER (Bit Error Ratio) Type II BER <2.4% at -102dBm
Type II BER <0.1% at -15dBm

- 10 -
2. TECHNICAL BRIEF
2-1. Receiver
1. The front end
The RF receive signal (GSM 935Mhz - 960MHz, DCS 1805Mhz - 1880Mhz) is input via the antenna or
coaxial connector. An antenna matching circuit is between the antenna and the connector.
The diplexer U23 is used to control the Rx and Tx paths. And the input signal RX_TX_B of pin 2 of Q19
is connected to U1(SC1688) to switch either Rx or Tx path on. When the Rx path is turned on, the RF
receives signal then feeds into two paths, Rx_1800_RF and Rx_900_RF.
This Rx_1800_RF path contains one SAW filter U46 to filter any unwanted signal apart from the DCS
Rx band. And the U45 in the Rx_900_RF path is to filter out unwanted signal beyond the GSM Rx
band. These two paths are then connected to the DLNAI (# 2) and GLNAI(# 4) of W3020(U31)
respectively.
The RF receive signal is amplified by LNAs in W3020 with the output at DLNAO (# 63) and GLNAO (#
61) respectively, and then pass through the SAW filters B4635 (U22) and B4684 (U10). After this
filtering process, the signal then feeds into U31 for mixing with LO, which is produced by the
synthesiser W3000 (U19), and two VCOs.
In W3020, UHF mixers produce a IF signal of frequency 270 MHz at RMON (# 51) and RMOP (# 50) in
differential mode. This differential signal is filtered by B4836 (U50), a 270 MHz SAW filter, and then fed
to W3020 #34 and #35.

2. TECHNICAL BRIEF
- 11 -
2. RX I&Q Demodulator
The modulated IF signal is demodulated by mixing with a 270 MHz signal, which was derived from the
540Mhz oscillator. Before the mixer is a 32db gain IF amplifier which can be set to either 0 or 32db of
gain. The mixer has 6db gain itself, and then followed by two low-pass filters and five baseband
amplifiers.
The W3020 produces demodulated baseband signals at RIP (# 47), RIN (# 46), RQP(# 45) and RQN(#
44) which are connected to SC1688(U1) .

- 12 -
3. UHF Synthesizer (Rx)
The synthesizer for RX and TX UHF are implemented by W3000 (U19). The outputs of DCS VCO
(1530 ~ 1610 MHz) and GSM VCO (1160 ~ 1230 MHz) are fed to U19 #5 for phase comparison in
order to generate the charge pump output U19 #2 to control the frequency of VCOs. On the locked
state, the frequency of VCO is
Fvco=[(P*M)+A] * fref / R
Where
Fref is the frequency of the signal on U19 #10. Here is 13 MHz.
P, M, A, R are all constants set by the three-wired digital control bus:
DATA #13
LATCH #14
CLOCK #12
The loop filter between U19 #2 and VCO #5 converts the current signal on U19 #2 to the voltage signal
on VCO #5.
Q15 is a switch, which controls the power supply of VCOs.

2. TECHNICAL BRIEF
- 13 -
4. The Rx IF Synthesiser
The major part of Rx IF synthesiser is built in W3020 including a phase comparator, and a charge
pump, etc. Outside the W3020, the C164 and R189 and C225 form the loop filter; Q31 is a power
switch and the VCO would be locked at 540 MHz.
In the W3020, this 540 MHz signal is divided by 2 for the receiver, divided by 2 for the GSM Tx and
divided by 3 for the DCS Tx.

- 14 -
2-2. Transmitter
[The TX IF Modulator in W3020]
1. The TX IF Modulator
The TX I & Q signals from U1 #86-89 are fed to #38-41 of the W3020 TX modulator (U31), where they
are then modulated onto either a TX IF of 270Mhz (for GSM-TX) or 180Mhz (for DCS-TX) by the
quadrature-mixer inside U31.
The signal TX LO IF (180-270Mhz) is input from U31. This signal is produced by the external 540Mhz
oscillator (U42), which has been divided down by a factor of 2 for GSM-TX or 3 for DCS-TX. This
division factor is set by the control signal of U31 #28-30. The TX modulated IF signal of 180/270Mhz is
output on #52-53 of U31 for GSM/DCS.
2. The TX IF Synthesizer
The second local oscillator (LO2), comprising a buffer for the external voltage-controlled oscillator
(VCO) and a phase-locked loop (PLL), feeds the IF portions of both the modulator and the receiver. An
external reference source, voltage-controlled crystal oscillator (VCXO), is divided from 13 MHz to 1
MHz through a counter. The 1 MHz is called the comparison frequency. The VCO(U42) frequency of
540 MHz is also divided down to 1 MHz. Both signals are fed into a phase detector, and the resultant
error signal is fed through an external low-pass filter to the control input of the VCO (U42).

2. TECHNICAL BRIEF
- 15 -
[The UHF Mixer/Amplifier/TX UHF Synthesiser]
3. The UHF Mixer Amplifier
The modulated TX IF signal GSM (270Mhz) or DCS(180Mhz) is mixed onto the GSM(890Mhz-915Mhz)
or DCS(1710Mhz-1785Mhz) TX RF frequency. This is achieved by mixing the TX IF signal with the TX
UHF VCO output from U30 for GSM and U29 for DCS. Hence:
GSM TX = UHF VCO - 270 ie, (1160 - 270 = 890Mhz)
DCS TX = UHF VCO +180 ie, (1530 + 180 = 1710 Mhz)
The modulated RF signal is then output on #59-60 to a BPF and then enters the UPC2771TB (U3/U43)
at #1. The RF modulated signal is then amplified by the Pre-driver with the UPC2771TB IC.
The RF signal is then output on #4 of the UPC2771TB and passed through another stage of filtering
(BPF: U4/U44).

- 16 -
4. The TX UHF Synthesizer
In TX mode the TX UHF VCO output is fed to #5 (U19) and then pre-scaled down to 200khz. The
phase comparator within U19 compares this signal with a 200khz signal derived from the 13Mhz clock
(U35) and outputs a current phase difference at #2. A loop filter then converts this signal into a voltage
phase difference and feeds it to #5 (U29) or (U30). The voltage phase difference determines the UHF
VCO frequency i.e. GSM TX 1160Mhz -1185Mhz, DCS TX 1530Mhz - 1610Mhz. Three control inputs
are used in the UHF Synthesiser SERDA, SERCK, SERLT. It is the SERDA control input, which initially
sets the TX VCO frequency. This is totally dependent on the chosen traffic channel the logic circuit has
selected at the time.
[The Power Amp Circuit]
5. The PA Circuit
The power amplifier control circuit ensures that the RF signal is regulated to the required limits of
operation. The TX RF signal is input on #3(U9) or (U32) and the power amplifier outputs the signal at
#10. The diplexor is tuned to the GSM or PCN duplex spacing so enabling selectivity between GSM
and PCN Rx or Tx.

2. TECHNICAL BRIEF
- 17 -
2-3. The PA Circuit and its Control
1. The PA Circuit and its Control
The power amplifier control circuit ensures that the RF signal is regulated to the required limits of
operation.
Power-control is carried out according to the measurement of the power-output of the P.A. (RF_Detect,
see Fig.: P.A Circuit Control). A voltage drop, which is converted from the RF power through a Diode-
Detector, is then integrated by the operational amplifier (U21) to give an error voltage regulates the
TXP signal.
The TXP input signal to the power control circuit is generated by the U1 #90. TXP provides a limit for
the frequency spectrum caused by burst modulation.
VDD_TXBUF (2.85V) is the main power supply for power control circuit. An op-amp, U21, which
outputs a control signal, but is not enough to drive the P.A. to the maximum output. Q20 and Q26 are
an extra amplifier and buffer stage that use Vbat (more than 3.5V) in order to drive the control signal to
a sufficient level for P.A.
The power control circuitry has two different loop gains for increasing the dynamic power control range
and it is switched by U54 that is controlled by the control supply, PCL_SW.
The control supplies, PA_900_EN_B and PA_1800_EN_B control the switches Q28 and Q29 to make
sure the control signal goes to the right PA, VRAMP_900 and VRAMP_1800.

- 18 -
2-4. 13 MHz Clock
The 13 MHz-clock (END3352B) consists of a TCXO (Temperature Compensated Crystal Oscillator)
which oscillates at a frequency of 13MHz.
It's used within the W3000 Synthesizers, Communication Protocol processor (CPP), and Super Chip 1
(SC1689).
NC7S04 buffer the output to CPP, SC1 and W3000.

2. TECHNICAL BRIEF
- 19 -
2-5. Main Processor and DSP
1. Main Processor CPP-C
The CPP-C is a Lucent Technologies designed processor. The CPP-C performs the following
functions:
• CPU
• CPU Interface
• Interrupt Controller
• Baseband Power Control
• Keypad Control
• Display Interface
• Buzzer Control
• UART Control/Interface
• I/O System Connector Interface
• Battery Voltage Monitoring
• Charge Control
• Real Time Clock
• CPU Timers
• Backlight Control
• Vibrator Control
[System Block Diagram of CPP-C]