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2-8
SCH-A302
Trouble Shooting
4-3. PLL Part Check Point
(1) VCO (Voltage Controlled Oscillator)
- Operating voltage is ok? OSC402 pin #7
- VT voltage is ok? OSC402 pin #5 (VT voltage was changed according to CH)
- Out is ok? OSC402 pin#1 output 1
st
local frequency each CH
(2) PLL(Phase Looped Lock)
- Operating voltages are ok? It use + 3.0 VR lines voltages
- TCXO_IN input is ok? U402 pin#8 It use TCXO Freq (19.68 MHz) for Reference.
4-4. Power Line Check Point
(1) U501 VBATT - #4 check
Reset - #B7 check
(2) X501 (Sleep X-tal) 32.768 MHz (pk-pk 2.7 v)
(3) TCXO(OSC401) 19.68 MHz
(4) IFR3000(U302) - #37 check TCXO-N (4.96 MHz) TCXO/N
#38 check CHIP X8-(9.84 MHz)
4-5. Reference Regulators
PM1000 U501
RESET : B7 RESET SIGNAL OUT
3.0_RX : H5 - RX CIRCUIT OPERATING VOLTAGE
3.0_TX : G5 TX CIRCUIT OPERATING VOLTAGE. (Controlled By Idle Signal)
3.0_IF : H7 RFT3100,IFR3000 AND Etc.
4-6. SAMPLING REPAIR RESULT (SCH-A302)
(1) No.1 : 24108148669 Tx Power Problem
- TX IF does not out from RFT3100 (U204) pin#1,2.
- 2
nd
local and operating voltages (3.0 IF,3.0 VR,VDC) are ok.
- Estimated factor: IFT After replace IFT It working ok.
(2) No.2 : 24108205255 - Tx Power Problem
- TX IF does not out from RFT3100 (U402)pin#6,7.
- 2
nd
local and operating voltages (3.0_MP, 3.0_TX, 3.0_TX_IF, 3.0_TXRF, 3.0_TX_LO) are ok.
- PA ON signal does not out from MSM.
- MSM also failed to J-TAG Tester.
- Estimated factor: MSM defect