Sony Ericsson K750 User manual

Trouble Shooting Guide, Mechanical
4/000 21-1/FEA 209 544/94 C
© Sony Ericsson Mobile Communications AB
Trouble Shooting Guide, Mechanical
Applicable for K750
Contents
1
General...........................................................................................2
1.1. Service functions in the software....................................2
1.2. Misuse and other no warranty issues.............................3
2 Appearance Problems....................................................................6
3 Network/Signal Problems ...............................................................9
4 On/Off Problems...........................................................................10
5 Audio Problems ............................................................................12
6 Key Problems ...............................................................................16
7 Display Problems..........................................................................19
8 Illumination Problems ...................................................................21
9 Alert Problems..............................................................................23
10 SIM Problems...............................................................................25
11 Charging/Capacity Problems........................................................26
12 Camera Problems.........................................................................27
13 Data Communication Problems....................................................30
14 Hands-Free Problems...................................................................32
15 Software Problems .......................................................................32
16 Revision History............................................................................33

Trouble Shooting Guide, Mechanical
4/000 21-1/FEA 209 544/94 C
© Sony Ericsson Mobile Communications AB 2(33)
1 General
This document outlines the mechanical repairs that should be made in an attempt to fix the common failures that are seen in the field. To gain a
complete understanding of how to test and repair a specific failure, this document should be used in conjunction with the Test Instructions,
Mechanical and the Working Instructions, Mechanical.
1.1. Service functions in the software
The service menu will be accessed with the following key combination. Use the joystick.
⇒*⇐⇐*⇐*
They are as follows:
Service info
Service tests
Text labels
The phones software has a built in service functionality that allows you to test some of the phones functions. (See point 2 above) It looks like this:
Main display
LED/illumination
Keyboard
Speaker
Earphone
Microphone
Vibrator
Camera
Flash LED
Memory Stick
Real time clock
FM radio (You need a headset to test)
Total call time
NOTE: Different names may occur depending on language setting and customization.

Trouble Shooting Guide, Mechanical
4/000 21-1/FEA 209 544/94 C
© Sony Ericsson Mobile Communications AB 3(33)
1.2. Misuse and other no warranty issues
Misuse is not covered by warranty. This chapter will explain what’s not covered by warranty. Phones that have been exposed to misuse will not
be covered by warranty.
This means: if it is possible to repair the phone, the customer will have to pay for the repair. SEMC will not allow any of these phones to be
claimed into WCMS. Some local perspectives may interfere with this. Please reference to local directives.
1.1.1 Action
Make a general visual inspection for misuse.
Below are some examples of what is not covered by warranty.
Front window broken due
to misuse. LCD cracked due to drop. Clear scratches Mark after drop Corrosion components on the PCB.
Corrosion components on the PCB. Corrosion components on the PCB. SIM reader damaged by liquid. System connector damaged by liquid

Trouble Shooting Guide, Mechanical
4/000 21-1/FEA 209 544/94 C
© Sony Ericsson Mobile Communications AB 4(33)
Components around system
connector damaged by liquid System connector pad(s) damaged by liquid
1.1.2 Liquid damage sticker
In the phone there is placed a sticker that can give you a hint to see if the phone is damage by liquid or not. This sticker is located near the SIM
reader (Fig. 1.2.1) and it is possible to see it without disassemble the phone.
Fig. 1.2.1

Trouble Shooting Guide, Mechanical
4/000 21-1/FEA 209 544/94 C
© Sony Ericsson Mobile Communications AB 5(33)
On the pictures below you will see the different between a sticker that has been in contact with liquid (Fig. 1.2.3) and with one that hasn’t (Fig.
1.2.2).
1.1.3 Action
Make a general visual inspection for misuse, corrosion or oxidation from liquid damage. No further action should be taken for a liquid damaged
phone. Handle the unit according to local directives.
This sticker is ok This sticker is not ok
The white sticker that has been in contact with
liquid turns into a red or pink sticker. In this case
you should check the phone for liquid damage
(See point 1.1.1).
Note: There must be clear marks after liquid on the
PCB before rejecting the phone for repair.
Fig. 1.2.2 Fig. 1.2.3

Trouble Shooting Guide, Mechanical
4/000 21-1/FEA 209 544/94 C
© Sony Ericsson Mobile Communications AB 6(33)
2 Appearance Problems
Problem Area Items to Check Repair Action Reference Image
Appearance Visually inspect the cosmetic quality of all
user viewable surfaces
Front
System connector
Joystick button
Frame assembly
IRDA window
Memory card rubber lid
Antenna cover assembly
Battery cover assembly
Co-brand inlay
• If dirty – Clean parts as necessary.
• If unacceptably scratched or damaged –
Replace damage parts as necessary.
NOTE: Misuse is not covered by warranty.
Refer to chapter 1.2

Trouble Shooting Guide, Mechanical
4/000 21-1/FEA 209 544/94 C
© Sony Ericsson Mobile Communications AB 7(33)
Problem Area Items to Check Repair Action Reference Image
Visually inspect all keys
Keyboard
On/Off key
Music key
Volume key
Camera key
• If dirty – Clean parts as necessary.
• If unacceptably scratched or damaged –
Replace damaged parts as necessary.
NOTE: Misuse is not covered by warranty.
Refer to chapter 1.2

Trouble Shooting Guide, Mechanical
4/000 21-1/FEA 209 544/94 C
© Sony Ericsson Mobile Communications AB 8(33)
Problem Area Items to Check Repair Action Reference Image
Visually inspect for improper gap between
seams • Reassemble or replace damaged parts as
necessary.

Trouble Shooting Guide, Mechanical
4/000 21-1/FEA 209 544/94 C
© Sony Ericsson Mobile Communications AB 9(33)
3 Network/Signal Problems
Problem Area Items to Check Repair Action Reference Image
Before proceeding !Perform a flash upgrade.
Visually inspect SIM holder • If dirty or oxidized – Clean it.
• If damaged – Send to an electrical repair
location.
No Signal or Poor
Signal
Visually inspect antenna contact pads • If dirty or oxidized – Clean the pads and
replace the antenna assembly.

Trouble Shooting Guide, Mechanical
4/000 21-1/FEA 209 544/94 C
© Sony Ericsson Mobile Communications AB 10(33)
Problem Area Items to Check Repair Action Reference Image
Visually inspect antenna • If dirty or oxidized – Replace it.
• If damaged – Replace it.
If the issue has not been resolved !• Handle the unit according to local
directives.
4 On/Off Problems
Problem Area Items to Check Repair Action Reference Image
Check whether the phone vibrates 10 to 15
seconds after pressing the power key and
whether the keypad illuminates
• If activation of the vibrator and keypad are
detected, refer to the “Display Problems”
section
Power On problems
Before proceeding !• Perform a flash upgrade.

Trouble Shooting Guide, Mechanical
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© Sony Ericsson Mobile Communications AB 11(33)
Problem Area Items to Check Repair Action Reference Image
Visually inspect contact pads on battery • If dirty or oxidized – Clean pads.
• If damaged – Replace it.
Visually inspect battery connector • If dirty or oxidized – Clean it.
• If damaged – Send to an electrical repair
location.
Visually inspect the power key • If damaged – Replace it.
If the issue has not been resolved !• Handle the unit according to local
directives.

Trouble Shooting Guide, Mechanical
4/000 21-1/FEA 209 544/94 C
© Sony Ericsson Mobile Communications AB 12(33)
5 Audio Problems
Problem Area Items to Check Repair Action Reference Image
Before proceeding !• Perform a flash upgrade and a setting
reset.
Visually inspect the microphone’s external
port • If clogged - Clean or replace frame
assembly.
Visually inspect the microphone’s dust
cloth • If dirty or damaged – Replace frame
assembly.
Microphone:
If the issue has not been resolved !• Handle the unit according to local
directives.
Speaker:
No sound or poor
Before proceeding !• Perform a flash upgrade and a setting
reset.

Trouble Shooting Guide, Mechanical
4/000 21-1/FEA 209 544/94 C
© Sony Ericsson Mobile Communications AB 13(33)
Problem Area Items to Check Repair Action Reference Image
Visually inspect speaker’s external port • If clogged – Clean or replace front
assembly.
Visually inspect speaker’s dust cloth • If dirty or damaged – Replace front cover.
quality sound
Visually inspect the speaker’s contact pads
on the PCB • If dirty or oxidized- Clean pads.

Trouble Shooting Guide, Mechanical
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© Sony Ericsson Mobile Communications AB 14(33)
Problem Area Items to Check Repair Action Reference Image
Visually inspect the speaker pins • If damaged, dirty or oxidized – Replace
speaker box.
If the issue has not been resolved !• Replace speaker box.
If the issue has not been resolved !• Handle the unit according to local
directives.
Before proceeding !• Perform a flash upgrade and a setting
reset.Poly.-Speaker:
No sound or poor
quality sound Visually inspect speaker’s external port • If clogged – Clean or replace antenna
cover.

Trouble Shooting Guide, Mechanical
4/000 21-1/FEA 209 544/94 C
© Sony Ericsson Mobile Communications AB 15(33)
Problem Area Items to Check Repair Action Reference Image
Visually inspect the speaker’s dust cloth • If dirty or damaged - Replace antenna
cover.
Visually inspect the speaker’s contact pads
on the PCB • If dirty or oxidized- Clean pads.
Visually inspect the speaker pins • If damaged, dirty or oxidized – Replace
speaker box.
If the issue has not been resolved !• Replace speaker box.
If the issue has not been resolved !• Handle the unit according to local
directives.

Trouble Shooting Guide, Mechanical
4/000 21-1/FEA 209 544/94 C
© Sony Ericsson Mobile Communications AB 16(33)
6 Key Problems
Problem Area Items to Check Repair Action Reference Image
Keyboard:
A key on the
keyboard is not
functioning or is
intermittent
Visually inspect for debris between
keyboard and keyboard foil, and for
damage to the keyboard and the keyboard
foil.
NOTE: Camera switch is located on the
keyboard foil.
NOTE: Camera switch is a dual switch.
• If dirty – Clean both parts.
• If damaged - Replace keypad and/or
keyboard foil as necessary.

Trouble Shooting Guide, Mechanical
4/000 21-1/FEA 209 544/94 C
© Sony Ericsson Mobile Communications AB 17(33)
Problem Area Items to Check Repair Action Reference Image
Visually inspect whether the keyboard flex
film is properly connected to its connector
on the PCB
• If improperly connected – Re-establish
proper connection.
If the issue has not been resolved !• Replace the keyboard foil, if it has not
already been replaced.
If the issue has not been resolved !• Handle the unit according to local
directives.
Joystick: Visually inspect the joystick button • If dirty or damaged – Replace it.

Trouble Shooting Guide, Mechanical
4/000 21-1/FEA 209 544/94 C
© Sony Ericsson Mobile Communications AB 18(33)
Problem Area Items to Check Repair Action Reference Image
Visually inspect for damage to the side keys
Volume keys
Music key
Camera key
On/Off key
• If damaged - Replace keys as necessary.
Side keys
If the issue has not been resolved !• Handle the unit according to local
directives.

Trouble Shooting Guide, Mechanical
4/000 21-1/FEA 209 544/94 C
© Sony Ericsson Mobile Communications AB 19(33)
7 Display Problems
Problem Area Items to Check Repair Action Reference Image
Check whether the phone vibrates 10 to 15
seconds after pressing the power key and
whether the keypad illuminates
• If activation of the vibrator are not
detected, refer to the On/Off Problems”
chapter 2
Before proceeding !• Perform a flash upgrade and a setting reset.
LCD problem
Visually inspect whether the LCD flex film
is properly connected to its connector on
the PCB
• If improperly connected – Re-establish
proper connection.

Trouble Shooting Guide, Mechanical
4/000 21-1/FEA 209 544/94 C
© Sony Ericsson Mobile Communications AB 20(33)
Problem Area Items to Check Repair Action Reference Image
If the issue has not been resolved !• Replace the LCD.