Acer Aspire 8940 Service Guide

							Chapter 4191
Troubleshooting
Common Problems
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.
4.If the Issue is still not resolved, see “Online Support Information” on page 265.
Symptoms (Verified)Go To
Power On Issue Page 192
No Display Issue Page 193
Random Loss of BIOS Settings Page 194
LCD Failure Page 195
Internal Keyboard Failure Page 196
TouchPad Failure Page 197
Internal Speaker Failure Page 198
Internal Microphone Failure Page 199
HDD Failure Page 200
USB (Right side) Failure Page 201
Other Functions Failure Page 201
Motherboard CMOS discharge Page 201
Intermittent Failures Page 201
Undermined Failures Page 202
Chapter 4 
						

							192Chapter 4
Power On Issue
If the system doesn’t power on, perform the following actions one at a time to correct the problem. Do not 
replace non-defective FRUs:
Computer Shuts down Intermittently
If the system powers off at intervals, perform the following actions one at a time to correct the problem.
1.Check the power cable is properly connected to the computer and the electrical outlet. 
2.Remove any extension cables between the computer and the outlet.
3.Remove any surge protectors between the computer and the electrical outlet. Plug the computer directly 
into a known good electrical outlet. 
4.Disconnect the power and open the casing to check the Thermal Unit and fan airways are free of 
obstructions.
5.Remove all external and non-essential hardware connected to the computer that are not necessary to 
boot the computer to the failure point.
6.Remove any recently installed software.
7.If the Issue is still not resolved, see “Online Support Information” on page 265.
Start
Ch eck    
AC /Battery 
Power onSw ap AC   /Battery  to 
try
OK
NG
Ch eck 
Daughter/B & 
FFC Wh eth er 
OK
OK
Swap Dau gh ter/B
Re-plug PWR FFC
OK
NG
Swap M/B 
						

							Chapter 4193
No Display Issue
If the Display doesn’t work, perform the following actions one at a time to correct the problem. Do not replace 
non-defective FRUs:
No POST or Video
If the POST or video doesn’t display, perform the following actions one at a time to correct the problem.
1.Make sure that the internal display is selected. On this notebook model, switching between the internal 
display and the external display is done by pressing Fn+F5. Reference Product pages for specific model 
procedures.
2.Make sure the computer has power by checking at least one of the following occurs:
• Fans start up 
• Status LEDs light up
If there is no power, see “Power On Issue” on page 192.
3.Drain any stored power by removing the power cable and battery and holding down the power button for 
10 seconds. Reconnect the power and reboot the computer.
4.Connect an external monitor to the computer and switch between the internal display and the external 
display is by pressing Fn+F5 (on this model). 
If the POST or video appears on the external display, see “LCD Failure” on page 195.
5.Disconnect power and all external devices including port replicators or docking stations. Remove any 
memory cards and CD/DVD discs. Restart the computer.
If the computer boots correctly, add the devices one by one until the failure point is discovered.
6.Reseat the memory modules.
7.Remove the drives (see “Disassembly Process” on page 50).
8.If the Issue is still not resolved, see “Online Support Information” on page 265.
START
Power On?Nogoto no power
trouble shooting
step
Replace
Ext. DDR RAM 
moduleNo
NoScrew it wellReplace
M/B
Connect
it wellNo
LCD module
OK?NoReplace
LCD panel/
LCD cable
Ext. DDRRAM
module well
connected?
Ext. DDRRAM
module OK?
CPU thermal 
module well
screw? 
						

							194Chapter 4
Abnormal Video Display
If video displays abnormally, perform the following actions one at a time to correct the problem.
1.Reboot the computer.
2.If permanent vertical/horizontal lines or dark spots display in the same location, the LCD is faulty and 
should be replaced. See “Disassembly Process” on page 50.
3.If extensive pixel damage is present (different colored spots in the same locations on the screen), the LCD 
is faulty and should be replaced. See “Disassembly Process” on page 50.
4.Adjust the brightness to its highest level. See the User Manual for instructions on adjusting settings. 
NOTE: Ensure that the computer is not running on battery alone as this may reduce display brightness.
If the display is too dim at the highest brightness setting, the LCD is faulty and should be replaced. See 
“Disassembly Process” on page 50.
5.Check the display resolution is correctly configured:
a.Minimize or close all Windows. 
b.If display size is only abnormal in an application, check the view settings and control/mouse wheel 
zoom feature in the application. 
c.If desktop display resolution is not normal, right-click on the desktop and select 
Personalize´ Display Settings. 
d.Click and drag the Resolution slider to the desired resolution. 
e.Click Apply and check the display. Readjust if necessary.
6.Roll back the video driver to the previous version if updated.
7.Remove and reinstall the video driver.
8.Check the Device Manager to determine that:
• The device is properly installed. There are no red Xs or yellow exclamation marks. 
• There are no device conflicts. 
• No hardware is listed under Other Devices.
9.If the Issue is still not resolved, see “Online Support Information” on page 265.
10.Run the Windows Memory Diagnostic from the operating system DVD and follow the onscreen prompts.
11 .If the Issue is still not resolved, see “Online Support Information” on page 265.
Random Loss of BIOS Settings
If the computer is experiencing intermittent loss of BIOS information, perform the following actions one at a 
time to correct the problem.
1.If the computer is more than one year old, replace the CMOS battery.
2.Run a complete virus scan using up-to-date software to ensure the computer is virus free.
3.If the computer is experiencing HDD or ODD BIOS information loss, disconnect and reconnect the power 
and data cables between devices.
If the BIOS settings are still lost, replace the cables.
4.If HDD information is missing from the BIOS, the drive may be defective and should be replaced. 
5.Replace the Motherboard.
6.If the Issue is still not resolved, see “Online Support Information” on page 265. 
						

							Chapter 4195
LCD Failure
If the LCD fails, perform the following actions one at a time to correct the problem. Do not replace non-
defective FRUs:
Start
Check LCD 
modu le?Swap 
LCD cable /LCD  panel
OK
NG
Check MB LCD 
con n ector an d 
cable ?
OK
Reassemble
Re-plu g LCD cable
OK
NG
Swap M/B 
						

							196Chapter 4
Built-In Keyboard Failure
If the built-in Keyboard fails, perform the following actions one at a time to correct the problem. Do not replace 
non-defective FRUs:
STAR T
Keyboar d FPC
wel l connec te d?NoCo n n ec t
it  w el l
Ke yboa rd O K?NoReplace
keyboard
R epl ace  M /B 
						

							Chapter 4197
TouchPad Failure
If the To u c h P a d doesn’t work, perform the following actions one at a time to correct the problem. Do not 
replace non-defective FRUs:
Start
Check M/B T/P 
FFCRe-assemble th e 
T/P  F F C  to   M/B
OK
NG
Ch eck 
To u c h P a d
OK
Swap/Reassemble 
th e T/P  board  or 
T/P  F F C
OK
NG
Swap M/B 
						

							198Chapter 4
Internal Speaker Failure
If the internal Speakers fail, perform the following actions one at a time to correct the problem. Do not replace 
non-defective FRUs:
Sound Problems
If sound problems are experienced, perform the following actions one at a time to correct the problem.
1.Reboot the computer.
2.Navigate to Start´ Control Panel´ System and Maintenance´ System´ Device Manager. Check 
the Device Manager to determine that:
• The device is properly installed. 
• There are no red Xs or yellow exclamation marks. 
• There are no device conflicts. 
• No hardware is listed under Other Devices.
3.Roll back the audio driver to the previous version, if updated recently.
4.Remove and reinstall the audio driver.
5.Ensure that all volume controls are set mid range:
a.Click the volume icon on the taskbar and drag the slider to 50. Ensure that the volume is not muted.
b.Click Mixer to verify that other audio applications are set to 50 and not muted.
6.Navigate to Start´ Control Panel´ Hardware and Sound´ Sound. Ensure that Speakers are selected 
as the default audio device (green check mark).
NOTE: If Speakers does not show, right-click on the Playback tab and select Show Disabled Devices 
(clear by default).
Start
Check M/B  SPK 
cable Re-assemble th e 
SPK cable to  M/B
OK
NG
Ch eck Logic 
Upper/Logic 
upper
OK
Swap Logic 
lower/Logic u pper
OK
NG
Swap M/B 
						

							Chapter 4199
7.Select Speakers and click Configure to start Speaker Setup. Follow the onscreen prompts to configure 
the speakers.
8.Remove and recently installed hardware or software.
9.Restore system and file settings from a known good date using System Restore. 
If the issue is not fixed, repeat the preceding steps and select an earlier time and date.
10.Reinstall the Operating System.
11 .If the Issue is still not resolved, see “Online Support Information” on page 265.
Internal Microphone Failure
If the internal Microphone fails, perform the following actions one at a time to correct the problem. Do not 
replace non-defective FRUs:
Microphone Problems
If internal or external Microphones do no operate correctly, perform the following actions one at a time to 
correct the problem.
1.Check that the microphone is enabled. Navigate to Start´ Control Panel´ Hardware and Sound´ 
Sound and select the Recording tab.
2.Right-click on the Recording tab and select Show Disabled Devices (clear by default). 
3.The microphone appears on the Recording tab. 
4.Right-click on the microphone and select Enable.
5.Select the microphone then click Properties. Select the Levels tab.
6.Increase the volume to the maximum setting and click OK.
7.Test the microphone hardware:
a.Select the microphone and click Configure.
Start
Ch eck M/B  Mic. 
cable Re-assemble th e 
MIC cable to  M/B
OK
NG
Check MIC wire 
of LCD modu le
OK
Swap MIC  wire  of 
LCD modu le 
OK
NG
Swap M/B 
						

							200Chapter 4
b.Select Set up microphone.
c.Select the microphone type from the list and click Next.
d.Follow the onscreen prompts to complete the test.
8.If the Issue is still not resolved, see “Online Support Information” on page 265.
HDD Not Operating Correctly
If the HDD does not operate correctly, perform the following actions one at a time to correct the problem. 
1.Disconnect all external devices.
2.Run a complete virus scan using up-to-date software to ensure the computer is virus free. 
3.Run the Windows 7 Startup Repair Utility:
a.insert the Windows 7 Operating System DVD in the ODD and restart the computer. 
b.When prompted, press any key to start to the operating system DVD. 
c.The Install Windows screen displays. Click Next. 
d.Select Repair your computer. 
e.The System Recovery Options screen displays. Click Next. 
f.Select the appropriate operating system, and click Next. 
NOTE: Click Load Drivers if controller drives are required. 
g.Select Startup Repair. 
h.Startup Repair attempts to locate and resolve issues with the computer.
i.When complete, click Finish. 
If an issue is discovered, follow the onscreen information to resolve the problem.
4.Run the Windows Memory Diagnostic Tool. For more information see Windows Help and Support.
5.Restart the computer and press F2 to enter the BIOS Utility. Check the BIOS settings are correct and that 
CD/DVD drive is set as the first boot device on the Boot menu.
6.Ensure all cables and jumpers on the HDD and ODD are set correctly.
7.Remove any recently added hardware and associated software.
8.Run the Windows Disk Defragmenter. For more information see Windows Help and Support.
9.Run Windows Check Disk by entering chkdsk /r from a command prompt. For more information see 
Windows Help and Support.
10.Restore system and file settings from a known good date using System Restore. 
If the issue is not fixed, repeat the preceding steps and select an earlier time and date.
11 .Replace the HDD. See “Disassembly Process” on page 50.