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 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. 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.
Diagnostic LED
This section details the diagnostic features of the battery LED.
Instead of beep codes, errors are indicated through the bicolor Battery Charge/Status LED. A specific blink pattern is followed by flashing
a pattern of flashes in amber, followed by white. The pattern then repeats.
NOTE: The diagnostic pattern consists of a two-digit number being represented by a first group of LED blinks (1–9) in
amber, followed by a 1.5 s pause with the LED off, and then a second group of LED blinks (1–9) in white. This is then
followed by a three second pause, with the LED off, before repeating over again. Each LED blink takes 0.5 s.
110 Troubleshooting
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