Acer Aspire 7420 Service Guide

							Chapter 4103
Use the following procedure as a guide for computer problems.
NOTE: The diagnostic tests are intended to test only Acer products. Non-Acer products, prototype cards, or 
modified options can give false errors and invalid system responses.
1.Obtain the failing symptoms in as much detail as possible.
2.Verify the symptoms by attempting to re-create the failure by running the diagnostic test or by repeating 
the same operation.
3.Use the following table with the verified symptom to determine which page to go to.
Symptoms (Verified)Go To
Power failure. (The power indicator does 
not go on or stay on.)“Power System Check” on page 105.
POST does not complete. No beep or error 
codes are indicated.“Power-On Self-Test (POST) Error 
Message” on page 108
“Undetermined Problems” on page 122
POST detects an error and displayed 
messages on screen.“Error Message List” on page 109
Other symptoms (i.e. LCD display problems 
or others).“Power-On Self-Test (POST) Error 
Message” on page 108
Symptoms cannot be re-created 
(intermittent problems).Use the customer-reported symptoms and 
go to “Power-On Self-Test (POST) Error 
Message” on page 108
“Intermittent Problems” on page 121
“Undetermined Problems” on page 122
Troubleshooting
Chapter 4 
						

							104Chapter 4
System Check Procedures
External Diskette Drive Check
Do the following to isolate the problem to a controller, driver, or diskette. A write-enabled, diagnostic diskette is 
required.
NOTE: Make sure that the diskette does not have more than one label attached to it. Multiple labels can cause 
damage to the drive or cause the drive to fail. 
Do the following to select the test device.
1.Boot from the diagnostics diskette and start the diagnostics program.
2.See if FDD Test is passed as the program runs to FDD Test.
3.Follow the instructions in the message window.
If an error occurs with the internal diskette drive, reconnect the diskette connector on the system board.
If the error still remains:
1.Reconnect the external diskette drive/DVD-ROM module.
2.Replace the external diskette drive/CD-ROM module.
3.Replace the main board.
External CD-ROM Drive Check
Do the following to isolate the problem to a controller, drive, or CD-ROM. Make sure that the CD-ROM does 
not have any label attached to it. The label can cause damage to the drive or can cause the drive to fail.
Do the following to select the test device:
1.Boot from the diagnostics diskette and start the diagnostics program.
2.See if CD-ROM Test is passed when the program runs to CD-ROM Test.
3.Follow the instructions in the message window.
If an error occurs, reconnect the connector on the System board. If the error still remains:
1.Reconnect the external diskette drive/CD-ROM module.
2.Replace the external diskette drive/CD-ROM module.
3.Replace the main board.
Keyboard or Auxiliary Input Device Check
Remove the external keyboard if the internal keyboard is to be tested.
If the internal keyboard does not work or an unexpected character appears, make sure that the flexible cable 
extending from the keyboard is correctly seated in the connector on the system board.
If the keyboard cable connection is correct, run the Keyboard Test. 
If the tests detect a keyboard problem, do the following one at a time to correct the problem. Do not replace a 
non-defective FRU:
1.Reconnect the keyboard cables.
2.Replace the keyboard.
3.Replace the main board.
The following auxiliary input devices are supported by this computer:
Numeric keypad 
						

							Chapter 4105
External keyboard
If any of these devices do not work, reconnect the cable connector and repeat the failing operation. 
Memory check
Memory errors might stop system operations, show error messages on the screen, or hang the system.
1.Boot from the diagnostics diskette and start the doagmpstotics program (please refer to main board.
2.Go to the diagnostic memory in the test items.
3.Press F2 in the test items.
4.Follow the instructions in the message window.
NOTE: Make sure that the DIMM is fully installed into the connector. A loose connection can cause an error.
Power System Check
To verify the symptom of the problem, power on the computer using each of the following power sources:
1.Remove the battery pack.
2.Connect the power adapter and check that power is supplied.
3.Disconnect the power adapter and install the charged battery pack; then check that power is supplied by 
the battery pack.
If you suspect a power problem, see the appropriate power supply check in the following list:
“Check the Power Adapter” on page 106
“Check the Battery Pack” on page 107 
						

							106Chapter 4
Check the Power Adapter
Unplug the power adapter cable from the computer and measure the output voltage at the plug of the power 
adapter cable. See the following figure
1.If the voltage is not correct, replace the power adapter.
2.If the voltage is within the range, do the following:
Replace the System board.
If the problem is not corrected, see “Undetermined Problems” on page 122.
If the voltage is not correct, go to the next step.
NOTE: An audible noise from the power adapter does not always indicate a defect.
3.If the power-on indicator does not light up, check the power cord of the power adapter for correct 
continuity and installation.
4.If the operational charge does not work, see “Check the Battery Pack” on page 107.  Pin 1: +19 to +20.5V
Pin 2: 0V, Ground 
						

							Chapter 4107
Check the Battery Pack 
To check the battery pack, do the following:
From Software:
1.Check out the Power Management in control Panel
2.In Power Meter, confirm that if the parameters shown in the screen for Current Power Source and Total 
Battery Power Remaining are correct.
3.Repeat the steps 1 and 2, for both battery and adapter.
4.This helps you identify first the problem is on recharging or discharging. 
From Hardware:
1.Power off the computer. 
2.Remove the battery pack and measure the voltage between battery terminals 1(+) and 6(ground). 
3.If the voltage is still less than 7.5 Vdc after recharging, replace the battery. 
To check the battery charge operation, use a discharged battery pack or a battery pack that has less than 50% 
of the total power remaining when installed in the computer. 
If the battery status indicator does not light up, remove the battery pack and let it return to room temperature. 
Re-install the battery pack.
If the charge indicator still does not light up, replace the battery pack. If the charge indicator still does not light 
up, replace the DC/DC charger board. 
Touchpad Check
If the touchpad doesn’t work, do the following actions one at a time to correct the problem. Do not replace a 
non-defective FRU:
1.Reconnect the touchpad cables.
2.Replace the touchpad.
3.Replace the system board.
After you use the touchpad, the pointer drifts on the screen for a short time. This self-acting pointer movement 
can occur when a slight, steady pressure is applied to the touchpad pointer. This symptom is not a hardware 
problem. No service actions are necessary if the pointer movement stops in a short period of time. 
						

							108Chapter 4
Power-On Self-Test (POST) Error Message 
The POST error message index lists the error message and their possible causes. The most likely cause is 
listed first.
NOTE: Perform the FRU replacement or actions in the sequence shown in FRU/Action column, if the FRU 
replacement does not solve the problem, put the original part back in the computer. Do not replace a 
non-defective FRU.
This index can also help you determine the next possible FRU to be replaced when servicing a computer.
If the symptom is not listed, see “Undetermined Problems” on page 122.
The following lists the error messages that the BIOS displays on the screen and the error symptoms classified 
by function. 
NOTE: Most of the error messages occur during POST. Some of them display information about a hardware 
device, e.g., the amount of memory installed. Others may indicate a problem with a device, such as the 
way it has been configured. 
NOTE: If the system fails after you make changes in the BIOS Setup Utility menus, reset the computer, enter 
Setup and install Setup defaults or correct the error.  
						

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Index of Error Messages
Error Code List
Error CodesError Messages
006 Equipment Configuration Error
Causes:
1. CPU BIOS Update Code Mismatch
2. IDE Primary Channel Master Drive Error
(THe causes will be shown before “Equipment 
Configuration Error”)
010 Memory Error at xxxx:xxxx:xxxxh (R:xxxxh, W:xxxxh) 
070 Real Time Clock Error
071 CMOS Battery Bad
072 CMOS Checksum Error
110 System disabled.
Incorrect password is specified.
 Battery critical LOW
In this situation BIOS will issue 4 short beeps then shut 
down system, no message will show.
 Thermal critical High
In this situation BIOS will shut down system, not show 
message.
Error Message List
Error MessagesFRU/Action in Sequence
Failure Fixed Disk Reconnect hard disk drive connector.
“Load Default Settings” in BIOS Setup Utility.
Hard disk drive
System board
Stuck  Key see “Keyboard or Auxiliary Input Device Check” on page 104. 
Keyboard  error see “Keyboard or Auxiliary Input Device Check” on page 104. 
Keyboard Controller Failed see “Keyboard or Auxiliary Input Device Check” on page 104. 
Keyboard locked - Unlock key switch Unlock external keyboard
Monitor type does not match CMOS - Run 
SetupRun “Load Default Settings” in BIOS Setup Utility.
Shadow RAM Failed at offset: nnnn BIOS ROM
System board
System RAM Failed at offset: nnnn DIMM
System board
Extended RAM Failed at offset: nnnn DIMM
System board
System battery is dead - Replace and run 
SetupReplace RTC battery and Run BIOS Setup Utility to 
reconfigure system time, then reboot system.
System CMOS checksum bad - Default 
configuration usedRTC battery
Run BIOS Setup Utility to reconfigure system time, then 
reboot system. 
						

							11 0Chapter 4
System timer error RTC battery
Run BIOS Setup Utility to reconfigure system time, then 
reboot system.
System board
Real time clock error RTC battery
Run BIOS Setup Utility to reconfigure system time, then 
reboot system.
System board
Previous boot incomplete - Default 
configuration usedRun “Load Default Settings” in BIOS Setup Utility.
RTC battery
System board
Memory size found by POST differed from 
CMOSRun “Load Default Settings” in BIOS Setup Utility.
DIMM
System board
Diskette drive A error Check the drive is defined with the proper diskette type in 
BIOS Setup Utility
See “External Diskette Drive Check” on page 104. 
Incorrect Drive A type - run SETUP Check the drive is defined with the proper diskette type in 
BIOS Setup Utility
System cache error - Cache disabled System board
CPU ID: System board
DMA Test Failed DIMM
System board
Software NMI Failed DIMM
System board
Fail-Safe Timer NMI Failed DIMM
System board
Device Address Conflict Run “Load Default Settings” in BIOS Setup Utility.
RTC battery
System board
Allocation Error for device Run “Load Default Settings” in BIOS Setup Utility.
RTC battery
System board
Failing Bits: nnnn DIMM
BIOS ROM
System board
Fixed Disk n None
Invalid System Configuration Data BIOS ROM
System board
I/O device IRQ conflict Run “Load Default Settings” in BIOS Setup Utility.
RTC battery
System board
Operating system not found Enter Setup and see if fixed disk and drive A: are properly 
identified.
Diskette drive
Hard disk drive
System board Error Message List
Error MessagesFRU/Action in Sequence 
						

							Chapter 4111
Error Message List
No beep Error MessagesFRU/Action in Sequence
No beep, power-on indicator turns off and 
LCD is blank.Power source (battery pack and power adapter). See “Power 
System Check” on page 105.. 
Ensure every connector is connected tightly and correctly. 
Reconnect the DIMM.
LED board.
System board.
No beep, power-on indicator turns on and 
LCD is blank.Power source (battery pack and power adapter). See “Power 
System Check” on page 105.. 
Reconnect the LCD connector
Hard disk drive
LCD inverter ID
LCD cable
LCD Inverter
LCD
System board
No beep, power-on indicator turns on and 
LCD is blank. But you can see POST on an 
external CRT. Reconnect the LCD connectors.
LCD inverter ID
LCD cable 
LCD inverter
LCD
System board
No beep, power-on indicator turns on and a 
blinking cursor shown on LCD during 
POST.Ensure every connector is connected tightly and correctly.
System board
No beep during POST but system runs 
correctly.Spe ak er
System board 
						

							11 2Chapter 4
Phoenix BIOS Beep Codes
CodeBeepsPOST Routine Description
02h Verify Real Mode
03h Disable Non-Maskable Interrupt (NMI)
04h Get CPU type
06h Initialize system hardware
08h Initialize chipset with initial POST values
09h Set IN POST flag
0Ah Initialize CPU registers
0Bh Enable CPU cache
0Ch Initialize caches to initial POST values
0Eh Initialize I/O component
0Fh Initialize the local bus IDE
10h Initialize Power Management
11h Load alternate registers with initial POST 
values
12h Restore CPU control word during warm 
boot
13h Initialize PCI Bus Mastering devices
14h Initialize keyboard controller
16h 1-2-2-3 BIOS ROM checksum
17h Initialize cache before memory autosize
18h 8254 timer initialization
1Ah 8237 DMA controller initialization
1Ch Reset Programmable Interrupt Controller
20h 1-3-1-1 Test DRAM refresh
22h 1-3-1-3 Test 8742 Keyboard Controller
24h Set ES segment register to 4 GB
26h Enable A20 line
28h Autosize DRAM
29h Initialize POST Memory Manager
2Ah Clear 215 KB base RAM
2Ch 1-3-4-1 RAM failure on address line xxxx
2Eh 1-3-4-3 RAM failure on data bits xxxx of low byte 
of memory bus
2Fh Enable cache before system BIOS 
shadow
30h 1-4-1-1 RAM failure on data bits xxxx of high byte 
of memory bus
32h Test CPU bus-clock frequency
33h Initialize Phoenix Dispatch Manager
36h Warm start shut down
38h Shadow system BIOS ROM
3Ah Autosize cache