Power Control Loop - Nokia NSW-6 Series Disassembly & Troubleshooting Instructions

NSW-6
Disassembly & Troubleshooting

Power control loop

Power control section is basically similar for both bands, except for that
both bands have their own directional coupler and detector. The power
control is actually made in EROTUS IC.
Is V929, V930
voltage drop about
0.3–0.4 V
Y
Is TXLX functionality
OK ?
TXLX are LOW on
power levels PL 2 7
Y
Is DETO vs. output
power and TXC
OK?
See chart below.
TYPICAL DETECTED VOLTAGES AT POWER LEVELS PL2 PL10
800D
Pout
PL dBm
2 26.8
3 23.5
4 20.0
5 16.0
6 12.0
7 8.0
8 4.0
9 0.0
10 –4.0
Page 40
Check V930, V929
N
Check bias circuit
around diodes.
N Check PIN diode
bias components.
Check BB controls.
(BaseBand)
Check power
N
control components
near N700
Press N700
Change N700
Change N700
TXC LB–DETO
dac mV
250 1650
77 1350
–40 1120
–127 930
–187 840
–228 750
–188 840
–229 740
–290 650
E Nokia Mobile Phones Ltd.
PAMS Technical Documentation
Note !
See DETO vs. Output power
curve
Note:
1. DETO and TXC will be
about same in each mode.
2. TXA is high during modulation.
3. TXLX signals will draw about
4mA current in high state.
1900
D
Pout TXC
PL dBm dac
2 26.8
3 23.0
4 20.0
5 16.0 –128
6 12.0 –177
7 8.0 –215
8 4.0 –205
9 0.0 –253
10 –4.0 –329
UB–
DETO
mV
124 1478
27 1275
–53 1120
937
831
762
768
693
531
Issue 1 12/99