Varios

Service
Diagrams

Introduction
The service diagrams were carefully prepared to allow
a Motorola certified technician to easily troubleshoot
cellular phone failures. Our professional staff provided
directional labels, color coded traces, measurement values and other guidelines to help a technician troubleshoot a cellular phone with speed and accuracy.

Because of the sensitivity of RF,measured readings will
be greatly affected if they’re taken in certain locations.
To get the most accurate readings, take measurements
nearest to the labeled measurement on the service diagram.

We worked hard in trying to provide the best service
diagrams, therefore, to avoid cluttered diagrams, we
may exclude some components from the service diagrams. Our professional staff carefullyselected to excluded components that are unlikely to fail.

Test Point Measurements
The measurements labeled on the service diagrams are
approximate values and may vary slightly. These measurements are dependent on the accuracy of the test
equipment.
It is strongly recommended that the test equipment calibration schedule be followed as stated by the manufacturer. RF probes should be calibrated foreach frequency
in which tests are going to be performed.
The types of probes used will also affect measurement
values. Test probes and cables should be tested for RF
losses and loose connections.

Preliminary

Motorola Confidential Proprietary

4-1

4-2

A920: Antenna Circuit

Int Antenna
M001

Ext Antenna

Ant
Match
WCDMA_RX

GSM_RX

GSM
RF SECTION

FL001
FEMDCS_RX
PCS_RX
GSM_TX
DCS_PCS_TX

N_BAND_0_G

GSM_EXC_EN

Q902

Motorola Confidential Proprietary

N_GSM_EXC_EN

N_BAND_1

N_BAND_0

WCDMA
RF SECTION

FL030

CMOS level shifter
Decoder ASIC

RX_EN_LIFE

MAGIC
LV

WCDMA_TX

FL010

HARMONY
LITE

HL_TX_EN

GSM TX VCO

VRF_TX_2_775V

Description

POG

Q901
NB_EXC_EN

Q906

N_BAND_0

MAGIC LV

Allcellular receive bands are fed into either the internal antenna or external antenna. M001 is a mechanical switch which has the internal antenna path connected when a
no insertion condition exists. The RF path will switch to external antenna upon insertion of a male SMA connector to M001. The internal antenna path is fed to the
FEM(Front End Module) through antenna matching components. The FEMprovides band selection and filtering between the EGSM, DCS, PCS and WCDMA receive
and transmit bands to a single antenna port. GSM band selection is done by control lines N_BAND_1 and N_BAND_0_G. Mode selection is done by control lines
HL_TX_EN, RX_EN_LIFE, N_GSM_EXC_EN, and GSM_EXC_EN. The diplexing arrangement permits reception of WCDMA signals in any FEM switch position.
This allows thephone, while in a GSM call in any band, to detect signals from a WCDMA base station. The decision may then be made to hand over to the WCDMA
system. Similarly, EGSM base station signals can be detected while the phone is in a WCDMA call to permit a handover decision from WCDMA to EGSM (This is not
possible for base station signals in the DCS and PCS bands.).
Signals received at the antenna between2110 - 2170MHz will see the RF switch as an open circuit at any position. Consequently WCDMA Rx signals will go through
FL2 to the WCDMA receiver. FL2 should have a maximum insertion loss of ~0.5dB. Outside of the WCDMA Rx band, FL2 behaves as an open circuit, preventing outof-band signals from reaching the WCDMA receiver.
GSM, DCS, and PCS receive signals from the antenna port through the FEMshould have a maximum insertion loss of -4.4dB. The FEM EGSM transmit path should
have a maximum insertion loss of -2.5dB. The FEM DCS transmit path should have a maximum insertion loss of -3.1dB. The FEM PCS transmit path should have a
maximum insertion loss of -3.7dB.
Q902 is a dual FET package that’s being used to multiplex function of the N_BAND_0 control signal coming from the Magic LV....