Samsung SCH-A302 Service Manual page 12

SCH-A302
Trouble Shooting
4. Repair Guide
4-1. TX Part Check Point
Using commands in test mode
-01, 09 (0363), 07, 34, 71 (380)
(1) 130.38 MHz (TX IF) output line
- RFT3100 (U204) PIN #14,#15 (about -30 dBm)
- IF TXIF problem Then Check TX 2
nd
- TX 2 LOCAL check - RFT 3100 PIN #19 (about 23 dBm)
(2) TXRF (824~849 MHz) out lines.
From RFT3100 (U204) pin #15 to CELLA_OUT
- F201 input and output is ok? - Pin #2 and #5 (about 16 dBm)
- PAM input is ok? U201 pin #2 (about 20 dBm)
- PAM voltage is ok? U201 pin #3 (3 V), 1,4 (3.7 V)
- PA output is ok? U201 pin #5 (about +10 dBm)
- Duplex input and out put is ok? Duplex input is same with PAM output.
Output is You can check CN302 #2 (about 10 dBm)
4-2. RX Part Check Point
(1) RX RF (869~894 MHz) Signal input lines.
- HP Equipment setting
- RF ch 363 (RX:880.89 MHz, TX:835.89 MHz)- at CALL CTRL MENU
- sctr A pwr : -25 dBm (for more easy to check use Spectrum Analyzer)
- Rf Lvl offset : -1.4 at config screen
- Spectrum Analyzer Setting
- center Freq: 880.89 MHz (when check RXRF in 363 Ch)
- span : 5 MHz
- RF input line from Duplex to Mixer check point
- CN302 input and Duplex out (You can check Duplex out at C652) is ok?
- LNA (U360)input ,output and operating voltage is ok?
:Operating voltage-pin#1 (2.5 v) in & out (#3 66 dBm,#4 49 dBm)
- F303 input and output is ok? #2,#5 (about 50 dBm)
- RX Mixer (U361) input is ok? #1 (about 49 dBm)
(2) RF IF circuit (Received RXRF Signal + 1
st
- 1 local is ok? U361 #4,#5 (about 13 dBm)
- Voltage is ok? U361 pin #3 3.0v
- Mixer output is ok? U361 pin #6 RXIF (85.38 Mhz-fixed) (about 50 dBm)
- F301 input and output is ok?
(3) IFR (U302) neighbor circuit
- IF input is ok? U300 pin #11,12 (about 75 dBm)
nd
- RX 2 local is ok? U300 pin #21,22 (about 25 dBm)
- 3.0 V IF (3.0IF) lines are ok? IFR operating voltage
nd
LOCAL (260.76 MHz)
st
SAMSUNG Proprietary-Contents may change without notice
local = RX IF (85.38 MHz fixed)
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