Acer Travelmate 4720 Service Guide

Chapter 4101
*  If the BIOS detects error 2C, 2E, or 3O (base 512K RAM error), it displays an additional word-bitmap (xxxx) indicating 
the address line or bits that failed. For example, 2C 0002 means address line 1 (bit one set) has failed. 2E 1020 
means data bits 12 and 5 (bits 12 and 5 set) have failed in the lower 16 bits. Note that error 30 cannot occur on 386SX 
systems because they have a 16 rather than 32-bit bus. The BIOS also sends the bitmap to the port-80 LED display. It 
first displays the...

102Chapter 4
Index of Symptom-to-FRU Error Message
LCD-Related Symptoms
Symptom / ErrorCheck or do the following in sequence
LCD backlight doesnt work
LCD is too dark
LCD brightness cannot be adjusted
LCD contrast cannot be adjusted
TRun “Load Setup Defaults” in BIOS Setup Utility, then reboot 
system.
TReconnect the LCD connectors.
TKeyboard (if contrast and brightness function key doesnt 
work).
TLCD inverter ID
TLCD cable
TLCD inverter
TLCD
TMainboard
Unreadable LCD screen 
Missing pels in characters...

Chapter 4103
The system doesn’t power-off.TPower source (battery pack and power adapter). See “Power 
System Check” on page 93. 
THold and press the power switch for more than 4 seconds.  
TMainboard
Battery can’t be charged
TSee “Check the Battery Pack” on page 93. 
TBattery pack
TMainboard
PCMCIA-Related Symptoms
Symptom / ErrorCheck or do the following in sequence
System cannot detect the PC Card 
(PCMCIA) 
TPCMCIA slot assembly
TMainboard
PCMCIA slot pin is damaged. PCMCIA slot assembly...

104Chapter 4
The system doesnt resume from 
hibernation mode.TSee “Save to Disk (S4)” on page 44.
THard disk connection board
THard disk drive
TMainboard
The system doesnt resume from standby 
mode after opening the LCD.
TSee “Save to Disk (S4)” on page 44.
TLCD cover switch
TMainboard
Battery fuel gauge in Windows doesn’t go 
higher than 90%. 
TRemove battery pack and let it cool for 2 hours.
TRefresh battery (continue use battery until power off, then 
charge battery).
TBattery pack
TMainboard
System...

Chapter 4105
NOTE: If you cannot find a symptom or an error in this list and the problem remains, see “Undetermined 
Problems” on page 107. Modem-Related Symptoms
Symptom / ErrorCheck or do the following in sequence
Internal modem does not work correctly.
TModem phone port
TModem combo board
TMainboard 

106Chapter 4
Intermittent Problems
Intermittent system hang problems can be caused by a variety of reasons that have nothing to do with a 
hardware defect, such as: cosmic radiation, electrostatic discharge, or software errors. FRU replacement 
should be considered only when a recurring problem exists.
When analyzing an intermittent problem, do the following:
1.Run the advanced diagnostic test for the mainboard in loop mode at least 10 times.
2.If no error is detected, do not replace any FRU.
3.If any...

Chapter 4107
Undetermined Problems
The diagnostic problems does not identify which adapter or device failed, which installed devices are incorrect, 
whether a short circuit is suspected, or whether the system is inoperative.  
NOTE: Verify that all attached devices are supported by the computer.
NOTE: Verify that the power supply being used at the time of the failure is operating correctly. (See “Power 
System Check” on page 93.)
Follow procedures below to isolate the failing FRU. Do not isolate...

108Chapter 4 

Chapter 5109
System Block Diagram
System Block Diagram and Connector Locations
Chapter 5 

11 0Chapter 1
Board Layout
Top and Bottom View