DBTEL Incorporated
DB-6568 Service Manual Level 1 ~ 3
2003.11.13
DBTEL Copyright Reserved
Page 29 of 66
5.1.2 Classification of Malfunction
一
.
Operation related malfunction without handset disassembling: It divided into 3
categories.
1.
Fail to power on
: Fail to power on the phone or no response at all after connecting to
power source.
2.
Power on successfully but not working
: Current detected when pressing power key
after connecting to power source, but no power on/off prompt message and fail to activate
keypad backlight, LCD display backlight, ringer tone or vibration…etc.
3. Power on successfully but some of the functions do not function properly or are lost:
For
example, keypad malfunction, display error (such as arcane message displayed, LCD
display becomes totally black or white, font error), no sound and unable to dial.
二
. PCB related malfunction with housing disassembling: It divided into 3 categories.
i.
Power circuit failure
ii.
Logical malfunction:
13MHz oscillator, handset software defect
iii.
Reception/ transmission circuit failure
The above 3 categories are correlated, for example: the defect of handset software may
affect the input voltage, phase-lock loop in reception/transmission circuit, transmission
power level control, reception/transmission circuit time division synchronization and also,
the hardware circuit timing signal that provided by oscillator of reception/transmission
circuit for software operation may affect software performance as well.
5.1.3 Repairing Guidelines
Always follow guidelines listed below before fixing a defected handset:
：
一、
Determining the possible cause:
•
Always ask for the necessary information on possible cause of malfunction, such as
what’
s the problem and symptom, how and when does it occur; how often it does, etc.
before start fixing a handset.
•
Inspect the handset surface visibly to check that if housing is cracked or broken;
antenna is deflection or broken, keypad is being worn out and so on. Query
about whether the defect handset is purchased from other user or has ever been
repaired in elsewhere; the usage age of the handset, etc.
For an experienced technician, such critical information can help him to find out the
possible cause and defected components or parts effectively.
二、
Recording the type of malfunction
