Dell Latitude 3400 Service Manual - Page 112

Diagnostics, M-BIST - case

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8. Shut down the computer. 9. Press and hold the Fn key, while pressing the power button, and then release both. 10. Repeat steps 3-7 above. Diagnostics Table 5. Diagnostics Purpose of diagnostic tool Trigger Indicator of fault Repair instruction M-BIST L-BIST Evaluates the health condition of the system board to have further resolution on "No Power", "No Post", and "No Video" symptom and reduce repeated dispatches. Checks if the system board is supplying power to the LCD display by performing an LCD Power Rail test, which allows for isolation of "No Video" symptom to Mainboard, LCD or Cable. Pressing M key and Power button Integrated into the single LED error code diagnostic. Automatically initiated during POST. Battery LED light with "Solid Amber" Battery indicator LED blink error code [Amber, White] = [2,8] Indicates a problem with the system Indicates a problem with the system board. board. M-BIST M-BIST is the system board's built-in self-test diagnostics tool that improves the diagnostics accuracy of system board embedded controller (EC) failures. M-BIST can be manually initiated before POST. NOTE: M-BIST can be manually initiated before POST(Power On Self Test). How to run M-BIST? M-BIST must be initiated on the system from a power-off state that is either connected to AC power or with battery only. 1. Press and hold both the M key on the keyboard and the power button to initiate M-BIST. 2. With both the M key and thepower button that is held down, the battery indicator LED may exhibit two states. a. OFF: No fault detected with the system board. b. SOLID AMBER: Indicates a problem with the system board. L-BIST L-BIST (LCD Power Rail Test) is an enhancement to the single LED error code diagnostics and is automatically initiated during POST. LBIST will check the LCD power rail. If there is no power being supplied to the LCD (i.e., the L-BIST circuit fails), the battery status LED will flash an error code [2,8]. NOTE: If L-BIST fails, LCD-BIST cannot function as there is no power being supplied to the LCD. Running the L-BIST 1. Press the power button to start up the system. 2. If the system does not start up normally, look at the battery status LED. If the battery status LED flashes an error code [2,8], there is a failure on the LCD power rail of the system board, hence there is no power supplied to the LCD. 3. Replace the system board in this case. 112 Troubleshooting

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8.
Shut down the computer.
9.
Press and hold the Fn key, while pressing the power button, and then release both.
10.
Repeat steps 3–7 above.
Diagnostics
Table 5. Diagnostics
M-BIST
L-BIST
Purpose of diagnostic tool
Evaluates the health condition of the
system board to have further
resolution on "No Power", "No Post",
and "No Video" symptom and reduce
repeated dispatches.
Checks if the system board is supplying power to the
LCD display by performing an LCD Power Rail test, which
allows for isolation of "No Video" symptom to Mainboard,
LCD or Cable.
Trigger
Pressing
M
key and Power button
Integrated into the single LED error code diagnostic.
Automatically initiated during POST.
Indicator of fault
Battery LED light with "Solid Amber"
Battery indicator LED blink error code [Amber, White] =
[2,8]
Repair instruction
Indicates a problem with the system
board.
Indicates a problem with the system board.
M-BIST
M-BIST is the system board's built-in self-test diagnostics tool that improves the diagnostics accuracy of system board embedded
controller (EC) failures. M-BIST can be manually initiated before POST.
NOTE:
M-BIST can be manually initiated before POST(Power On Self Test).
How to run M-BIST?
M-BIST must be initiated on the system from a power-off state that is either connected to AC power or with battery only.
1.
Press and hold both the
M
key on the keyboard and the
power button
to initiate M-BIST.
2.
With both the
M
key and the
power button
that is held down, the battery indicator LED may exhibit two states.
a.
OFF:
No fault detected with the system board.
b.
SOLID AMBER:
Indicates a problem with the system board.
L-BIST
L-BIST (LCD Power Rail Test) is an enhancement to the single LED error code diagnostics and is automatically initiated during POST. L-
BIST will check the LCD power rail. If there is no power being supplied to the LCD (i.e., the L-BIST circuit fails), the battery status LED will
flash an error code [2,8].
NOTE:
If L-BIST fails, LCD-BIST cannot function as there is no power being supplied to the LCD.
Running the L-BIST
1.
Press the power button to start up the system.
2.
If the system does not start up normally, look at the battery status LED. If the battery status LED flashes an error code [2,8], there is a
failure on the LCD power rail of the system board, hence there is no power supplied to the LCD.
3.
Replace the system board in this case.
112
Troubleshooting