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NSD-6
Disassembly/Troubleshooting Instructions
(ICHAR) with the service software. When the PWM is off, current must be approxi-
mately 200uA. When the PWM is on, it must be greater than approximately 300mA.
CAFE
The CAFE ASIC performs various functions with respect to the RF circuitry and audio. It
digitizes the analog voice signals from the microphone as well as converts received digi-
tal data to voice signals to be sent to the earpiece. This also includes accessory micro-
phones and speakers. It also generates and decodes I and Q data for CDMA, and
demodulates FM (AMPS) signals. CAFE also acts as a clock squaring circuit and CDMA
clock generator.
Microphones
The internal microphone is biased using transistor V201, which is powered by VR1_SW
(TPD12, 2.75VDC). Check also the output of V201. V201, R220 and C212 should be
installed, and R202 should not be installed. MICP must be about 1.7VDC, and MICN must
be about 0.4VDC. Internal microphone bias is active only during a call. The XMIC is
biased by the AUXOUT signal (pin 75) through R209 and R208. The output voltage at pin
75 is about 1.5V.
Earpiece and XEAR
The internal earpiece is driven differentially from pins 77 and 80 (EARP and EARN). The
DC voltage on these two pins is 1.35V. The difference in the DC voltage between these
two pins must not be more than 50mV.
The XEAR signal drives audio to the external accessories. The CAFE signal name is HF (pin
81). The DC level on this pin should be 1.35V. HFCM (pin 82) should also be at 1.35V. The
difference in DC voltage between these two pins should not be more than 50mV.
Note that SGND is the return path for XMIC and XEAR.
Clock circuit
A 19.2MHz sinusoid should appear on pin 25 (Also TPD23). This is from the VCTCXO in
the RF. The CAFE will then produce a 19.2MHz clock at pin 18 (TPD25), and a 9.83MHz
clock on pin 19 (TPD24). See also Clocks section.
AMPSMOD
AMPSMOD is the voice signal to modulate (FM) the RF carrier for transmission. It is the
voice signal that has been processed by the DSP(MAD4) for transmission in AMPS mode.
It represents a modified version of the signal produced by the microphone (CAFÉ pin 58).
Transmit and Receive RF Signals
In CDMA mode, receive I and Q channel RF signals [RXIQ(3:0)] come into CAFÉ at pins 44,
45, 47, and 48. C207, C208, C209, and C210 can also be checked for these signals since
they are in series with the CAFÉ pins. Transmit I and Q RF signals [TXIQ(3:0)] can be seen
at pins 55, 56, 59, and 60 and C201, C204, C222, and C224.
Page 12
Nokia Mobile Phones Ltd.
PAMS Technical Documentation
Issue 1 04/01
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Table of Contents
Troubleshooting
