User Guide

PAMS
Technical Documentation
NHD–4
Disassembly & Troubleshooting
Page 30
Original 11/97
DC Node Voltage Checks
Typical nodal voltages are listed below. The phone must be at AMPS
output power level 2 or maximum CDMA output power when measuring
node voltages. These two states can be achieved by using the AMPS or
CDMA Troubleshooting Modes.
NODE CDMA
VDC
AMPS
VDC
VTXS – DC supply at C144 4.40 4.40
VTXT – DC supply at R120 5.30 5.30
V114 – Detector output ( TXI ) at N202 pin 1 1.20 1.10
V114 – Detector supply at R127 ( VTXS ) 4.40 4.40
V113 – CLY–10 PA supply at C160 ( VRFT ) 6.20 6.20
V113 – CLY–10 PA gate at R138 ( VGG ) –2.70 –2.30
V112 – 3rd Gain stage collector at C157 6.00 6.00
V112 – 3rd Gain stage base at C164 0.70 0.70
V112 – 3rd Gain stage supply at R117 6.3 6.20
V110 – 2nd Gain stage collector at C154 2.68 2.67
V110 – 2nd Gain stage base at R129 0.72 0.72
V111 – 1st & 2nd Gain stages supply at C108 4.70 4.70
V111 – 1st Gain stage collector at C146 3.85 3.83
V111 – 1st Gain stage base at R128 0.75 0.75
V106 – AT–109 atten. – supply at C129 ( VTXS ) 4.40 4.40
V106 – AT–109 atten. – control at C109 ( VC ) 3.50 4.35
N100 – Bias to the CDAGCT IC at C133 3.90 3.90
RFE2 at V107 emitter 0.00 3.10
VRFT– Battery voltage at C142 6.80 * 6.80 *
VNEG – Gate Volt. Delay at R111 –4.12 –4.05
TX_PUNC – Puncture Control at V102 3.12 3.12
TX_IREF – Control current reference at C115 3.60 3.50
TX_ICT – Control current at C100 3.60 3.50
Note This is the Battery voltage. It directly reflects the power supply voltage to the
phone. It will only be 6.8 V when the DC supply to the phone is 6.8 V.
Note: The position of the probe’s GND pin is critical to obtain correct readings. The GND
pin MUST be touching the GND plane immediately next to the point being measured!!
RF Node Power Levels
A high impedance passive RF probe may be used with a spectrum
analyzer to obtain the RF node power levels along the transmitter chain.
The author recommends a passive probe with a 500 ohm tip. The
following levels are based on a transmitter output at AMPS power level 7.
Maintain a 1.0 MHz span on the spectrum analyzer. A CDMA test box
with spectrum analyzer capabilities will do.
The RF power levels published below were found with a passive probe
with the 500 ohm tip. The blank column is reserved for values the user
will obtain with their own probe.