Voxtel V310, Service Manual

Page: 35 / 66

5-12
Troubleshooting
5.12 TX Power Trouble (E-GSM)
Set
• Phone : Test mode
62CH, 7 level setting (TCH)
62CH, -60dBm setting (BCCH)
•
Spectrum analyzer as shown in Remarks.
• Oscilloscope as shown in Remarks
REMARKS
1. Call connection : RF Repairs Program , Tx test
a. Test mode init
b. Test mode set
c. Band , Channel set (GSM , 62ch)
d. Power Level SET (7 level)
e. Tx ON
2. Spectrum analyzer : SPAN = 1 MHz
VBW = Auto
RBW = Auto
Press the trace button of spectrum analyzer on checking
test point and press the max hold of spectrum analyzer
3. Oscilloscope : 500mV/div , 2ms/div
4. RF Cable Loss : about 10dB
START
Check VC-TCXO
[X201 pin 3] is 26MHz oscillation.
Frequency = 26.00MHz
Power
≥ ≥ ≥ ≥
-15dBm
NO
NO
YES
YES
Check RF Main chip
U201 pin 4,5,6,7
I/Q signal
≥
≥ ≥
≥
DC1.35V&0.5Vp-p.
Check :
· X201 soldering.
· X201 pin 4 DC 2.85V + - 5%
· X201 pin 3 DC 1.4 + - 0.1V
Replace X201 if it’s defective.
Check :
· U201 pin soldering.
· Calypso.
· S/W.