5. Troubleshooting
5-1 Main Set
5-1-1 RX Sensitivity Problem
RX ON (RF Input - Frequency : CH Freq. + 20 kHz
- RF Amplitude : - 50 dBm)
No
Check U204, J401, C223
U204 Input e" -60 dBm?
Solder Status Resolder
Yes
No Check U109, U204, C224, F200
F200 Input e" -60 dBm?
Solder Status Resolder
Yes
No Check C219, L205, C217, C218, C216,
Q200 pin 1 e" -65 dBm?
R219 Solder Status Resolder
Yes
No
Q200, C216 Resolder or Replace
Q200 pin 3 e" -50 dBm?
Yes
No
Check L207, L206, R221, C220, C170,
F101 Input e" -50 dBm?
F101 Solder Status Resolder
Yes
U102
No
Input (pin47, 48)
Resolder C172, L104, C171
e" -55 dBm?
Yes
Check U102 (pin 42, 43, 44, 47, 48),
No
U102 pin 42, 43
R107, R109, C925, U839, C926, R504
e" -50 dBm?
Resolder or Change
Yes
F100
Check C168, C167, C164, R137,
No
pin 4, 5 e" -50 dBm
F100, C169, L108, L106, R138
(225 MHz)?
Solder status Resolder
Yes
U102
No Check C160, C159, C161, C162,
pin 38, 39 e" -55 dBm
L105, L204 Resolder or Charge
(225 MHz)?
Yes
No
Check U102, C164, L161
U102 pin 36, 37
e" -45 dBm (45MHz)?
Solder status Resolder
Yes
U102
No
Resolder or Check U102, C124,
pin 25, 26, 27, 28 30
L101, C119, R112 Resolder
mVp_p(20KHz)?
Yes
U411, C464, C445, L403, R466, L404,
No
U411 pin 7, 14
R465, R462, R468, R443, R445, R444,
1Vp_p(20KHz)?
L401, L402, R447 Resolder
Samsung Electronics 5-1
Troubleshooting
5-1-2 TX Power Problem
CH.60 (902 MHz) &
Tx Carrier ON (Power level 5)
RF VCO Resolder C147, C146, R135, R133,
e" -10dBm(1172MHz)?
No No R134, R132, R131, C142, C138, C139,
IF VCO e" -10dBm(540MHz)?
F201 Input e" - 10 dBm?
R504, C165, C927, R121, R120, R123,
TX VCO e" -10dBm
(902MHz)? C130 or replace if damaged.
Yes Yes
Check R208,R209,R210, C943,
F201 or replace if damaged.
No
F201 Resolder or Change F201
F201 Output e" -15 dBm?
Yes
No U202 pin 5 No
ResolderC208, U202 or
U202 Input e" - 15 dBm?
voltage e" 3V rms?
replace if damaged.
Yes Yes
Resolder U202 or
replace if damaged.
Resolder R215, C213, R212, C214,
No U202 pin 4 No
R213, C210, U206, U205,
U202 Output e" 30 dBm?
e" 2.0Vp_p(AC)?
U202,U203 or replace if damaged.
Yes Yes
Resolder FB100, U202, U204
or replace if damaged.
No U202, U204, U205, C225 Resolder
U204 Input e" 30 dBm?
or change poor component(s)
Yes
No
R139, C174, U204, U109
U204 Output e" 30 dBm?
Resolder or Change U204, U109
Yes
No
I/F Connector pin 21
C223, U204 J410 pin 21 Resolder
e" 30 dBm?
5-2 Samsung Electronics
Troubleshooting
5-1-3 Base Band
POWER ON
 POWER ON does not work
Give Battery Power
Yes
Check the Battery Voltage
Charge the Battery
is less than 3.2V
No
No
U402 pin 5 3.6V
Check the path from BATT to U402
(when pushing pwr Key)
Yes
U402 pin 2, 3, 4 No
Check the path from D401 to U402
3.3V (when pusging
(DC/DC convert circuit)
pwr Key)
Yes
No
Check the clock generation circuit
Check for the clock siganl
(related to U201 and U200)
at U408 pin 83
Yes
Check J301
Check the initial operation
END
Samsung Electronics 5-3
Troubleshooting
INITIAL OPERATION
Initial Failure
No
Check for the clock Check the clock generation circuit
signal at U408 pin 83? (related to U201 and U200)
Yes
Is it present
No
Check and repair the important
 CSROM signal on U833
signals of U408 as follows
(flash rom) pin 26?
Yes
No
U408 pin 28 =
Check U843
 H (SYSRST)
Yes
No
U408 pin 77 = Check R433 and
 H (BOOT) related circuit
Yes
No
U408 pin 84 = Check R428 and related
 H (DACT) circuit
Yes
U408
No
pin 37 (BUSREQ), pin 75 Resolder U408 pin 37, 75
(MSIZE) =  H
Check all the other connection
Yes
between U300 (flash rom) and
U450 (kernel)
No
U408 pin 74 =
Resolder U408 pin 74
 H (EXTPROC)
Yes
Check the circuit around LCD
Pin 54
No
(REFTXP) 3.0V
Check R471, R472, R473
Pin 53 (REFTXN)
0V
Yes
Pin 56
Check the circuit around U452
No
(REFADCP) 2.6V?
(E2PROM) and data stored in it
Check R470, R435, R469
Pin 58 (REFADCN)
0.3V?
Yes
END
Resolder all pins of U408
5-4 Samsung Electronics
Troubleshooting
BACKLIGHT
Checking the Menu
No
Backlight  ON mode? Select backlight  ON mode
Yes
U408 pin 76
No
Check the U450 and R426
and R426 =  H ?
Yes
No
Is Q400 drived? Check R425, R426 and Q400
Yes
No
Check the solder status of the LEDS
LED on?
and the related resistors
Yes
END
Samsung Electronics 5-5
Troubleshooting
RING INDICATOR LED
Ring Indicator LED does
not work
No
U408 pin 106 =  H ? Check the U408
Yes
No
Is U403 Drived? Check the U403
Yes
Check the LED
END
5-6 Samsung Electronics
Troubleshooting
SIM CARD PART
Phone can t access SIM card
After power ON,
No
Check the related of U402
U400 pin 4 and 5 =  H ?
Yes
Is there any
Yes
Resolder the connection
opened-connection between
between U400 and U408
U400 and U408?
No
After Power
No
Check continuity from
ON, Check SIMDATA Signal
U408 pin 14 to U400 pin 3
on U400 pin 3 in a
few second
Yes
After SIM card
No
Check the continuity from
insert, Check for the SIM CLK
U408 pin 10 to U400 pin 1
signal on U400 pin 1
Yes
No
After SIM card insert, Check the continuity from
U400 pin 2 (RST) =  H ? U408 pin 9 to U400 pin 2
Yes
Check the circuit around U412
(Serial E2PROM) and data stored in it
END
Samsung Electronics 5-7
Troubleshooting
KEY DATA INPUT
Check Initial operation
Does
the scanning Signals
No
Resolder pin 140, 141, 142, 143
come out from pin 140, 141, 142,
and 144 of U408 (kernel)
143, and 144 of
U408?
Yes
Resolder U408 pin 1, 2, 3, 4 and 5
No
Check the bad contact on any key and
Is the key data input OK?
clean the keypad area on the B D
Yes
END
5-8 Samsung Electronics
Troubleshooting
ALERT TONE
Abnormal Alert tone
Check the connection No
Resolder the connection from
from Buzzer to U308?
Buzzer to U308
Yes
No
Check the circuit related to U307
U307 pin 5 (AVCC) = 3.0V?
Yes
Does
No
the 13 MHz clock signal Check the connection from
Come out from the U405 U408 pin 85 to U405 pin 64
pin 64?
Yes
Is there alert wave
No
Resolder U405 pin 36
form on the U405 pin 36 during
alert tone test?
Yes
Is it present
No
the alert wave form on the Check the circuit around U308
U308 pin 5?
Yes
Check the circuit around
U452 (E2PROM)
END
Samsung Electronics 5-9
Troubleshooting
MICROPHONE PART
Microphone does not work
Resolder the connection
Check the connection
from Mic to J1001 (Ear-jack)
from MIC to J1001 (Ear-jack)
No
U307 pin 5 (AVCC) 3.0V? Check the circuit related to U307
Yes
Is there
No Check the connection from
the 13MHz clock signal on
U408 pin 85 to U405 pin 64
U405 pin 64?
Yes
Check connection
No
Resolder the R413, R417, R419,
from U405 pin 26, 27 to
R420, C430, C407 and C922
MIC+ and MIC-?
Yes
Check connection
No
Resolder the C406, C429,
from U405 pin 21, 22 to
C426 and C425
MIC+ and MIC-?
Yes
END
5-10 Samsung Electronics
Troubleshooting
SPEAKER PART
Speaker does not work
Check
No
Resolder the connection
the connection from Speaker to
from Speaker to SPK+ and SPK-
SPK+ and SPK-?
Yes
No
Check the circuit related to U307
U307 pin5 (AVCC) = 3.0V?
Yes
Is there the
Check the connection from
No
13 MHz clock signal on
U408 (kernel) pin 85 to
the U405 pin 64?
U405 (vocoder) pin 64
Yes
Check the
No
connection from U405 pin 30, 32 Resolder the U405 pin 30, 32
to SPK+ and SPK-
Yes
Check the speaker volume level
is appropriate
END
Samsung Electronics 5-11
Troubleshooting
CHARGING PART
Abnormal charging part
No
TA is OK? Replace TA
Yes
Check
No No
Resolder or replace U304
Is the LCD Display normal?
the voltage of U304 pin 14, 15
pin14, 15
9V?
Yes Yes
No
Check the U303 Resolder or replace
pin 3 4.1V? U303, U304
Yes
No
Check U408
Resolder or replace U408
pin 7 L?
Yes
Repair
END
5-12 Samsung Electronics