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Service Instructions
Ericsson Mobile Phone EF738
Service Instructions
2
Service Instructions
Contents
System Connector Signals ____________________________ 5
Disassembly________________________________________ 6
Reassembly ________________________________________ 7
Flip Mount Inspection______________________________________ 8
Warranty Seal ____________________________________________ 8
Exchanging the Circuit Board_________________________ 9
Fault Finding and Alignment ________________________ 10
Sequence of Adjustments __________________________________ 11
Item 1: VCTCXO ____________________________________________ 11
Item 2: RSSI Calibration ______________________________________ 12
Item 3: RF Output Power ______________________________________ 13
Item 4: Maximum Deviation ___________________________________ 14
Item 5: Nominal Deviation _____________________________________ 15
Item 6: SAT Deviation ________________________________________ 16
Item 7: TX Data Deviation _____________________________________ 17
Item 8: AFMS and Harmonic Distortion __________________________ 18
Item 9: Receiver Sensitivity ____________________________________ 19
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Service Instructions
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Service Instructions
System Connector Signals
External units are connected to the Transceiver Board via the 12-pin System Con-
nector.
1 2 3 11 12
Pin Signal In/Out Function
1 AFMS Out Audio From Mobile Station
2 ATMS In Audio To Mobile Station
3 EXTAUD In External Analog Audio Accessory Sense
4 AGND Audio Signal Ground, 0V reference
5 PORTHF In Portable Handsfree
6 MUTE Out Music Mute
7 VPPFLASH In Flash Memory Voltage and Service Voltage
8 VDD Out Logic Reference, Status ON
9 DFMS Out Data From Mobile Station
10 GND Digital Ground and DC Return
11 DTMS In Data To Mobile Station
12 DCIO In/Out DC positive pole for phone battery charging
and external accessory powering
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Service Instructions
Disassembly
1. Remove the battery and the antenna
Before opening the unit for further disassembly, make sure that the parts can be
placed on a dust-free ESD-protected surface.
NOTE! Do not touch the display with your fingers!
2. Place the phone on its front and remove four screws with the appropriate torx
screwdrivers.
3. Remove the back cover carefully from underneath.
4. Loosen the remaining screws (6, 10).
Be careful not to damage the antenna connector (7).
5. Carefully remove the board (1) from the front cover (2) by lifting it upwards.
6. Remove the keypad (4).
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Service Instructions
Reassembly
1. Place a front cover (2) on the workbench
Assemble the keypad (4).
2. Carefully place the board (1) into the front cover with the shield can upwards.
NOTE! Do not touch the display with your fingers
3. Drop a screw (10) into the upper right corner hole in the board.
Tighten the screw with a screwdriver (0.15Nm).
4. Drop an antenna connector (7) into the placement cavity of the antenna connec-
tor placement guide.
Ensure that the locating posts of the antenna connector are positioned in the mat-
ing holes of the board.
5. Drop a screw (6) into the screw hole in the antenna connector.
Tighten the screw with a scredriver (0.15Nm).
6. Mount the back cover (13) on the front cover (12).
Hold down the lower part of the back cover against the front cover and press the
upper part of the phone together.
7. Drop the four screws (14) into the holes on the back cover.
Tighten the screws with a screwdriver (0.15Nm).
8. Mount the antenna by screwing it clockwise into the thread.
9. Insert the battery pack into the phone and push until a click is heard.
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Service Instructions
Flip Mount Inspection
After mounting the flip;
Hold the telephone upside down and check that the flip is not open.
The flip must be closed as shown in fig. 1; not open as shown in fig. 2.
Fig. 1: Flip Closed
Fig. 2: Flip Open
Warranty Seal
Place the warranty seal over the right hand torx screw at the bottom.
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Service Instructions
Exchanging the Circuit Board
1. Transfer the EEPROM contents of the phone to the PC as described in section 3,
Test/Service Programs.
2. Disassemble as previously described in this section.
3. Exchange the board.
4. Reload the EEPROM customer data into the phone.
5. Check the function of the phone and, if necessary, align as described next in
Fault Finding and Alignment.
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Service Instructions
Fault Finding and Alignment
The table below shows information about test points and test data of the radio and
logic/audio parts of the board. This information will become an aid in testing as well
as fault finding. In general, the following procedure can be used:
1. Align the boards in the sequence stated below.
2. If a specific value cannot be obtained, use the tools mentioned in step 3 below to
trace the reason.
3. The built-in Test Program will provide access to the function or signal to become
investigated, and any signal data that may be required is found in the section
Connectors and Signals, where the distribution of signals at the respective con-
nector pins is found.
The telephone is tested, unless otherwise explicitly stated, with DC-power 6.2V
supplied via a dummy battery.
Channel 1 TP-1:1 (RX = 935.0125MHz, TX = 890.0125MHz)
RF Power Off TP-2:8
AFC Active TP-15:2
Audio Switches On TP-20:3 (TX & RX audio paths unmuted)
SAT Tone Off TP-22:3
Manchester Out Off TP-23:0
Volume 4 TP-25:4 (mid range)
TX Source ATMS TP-27:0
Earpiece External TP-28:2
Compandor Disabled TP-29:0 (disabled)
Softlimiter Off TP-32:0
Green LED Off TP-41:MENU+4:0
Red LED Off TP-41:MENU+5:0
ICTRL Off TP-41:MENU+2:0
Illumination Off TP-41:MENU+6:0
TP = Test Program
The above settings are automatically executed when entering the test program.
For detailed information regarding the adjustments, refer to subsection Test Pro-
gram in this section.
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Service Instructions
Sequence of Adjustments
Item 1: VCTCXO
Purpose:
Checking and, if necessary, calibrating the reference frequency generator for the
synthesizers
Test method:
Radio test set in TX mode, measured with a frequency counter
Input signal:
None
Measurement point:
Transmitter frequency at antenna connector
Limit:
890.0125MHz