MacBuild Laptop Eval

MacBuild Laptop Eval

Troubleshooting Guide

The laptop does not turn on

If a laptop does not turn on, or turns on for a split-second and turns off again, it usually indicates one of the following things:

• Drained battery AND bad power supply
• Bad RAM
• Logic board failure
• Power connector/DC-in board failure

Follow these steps to see if you can determine the cause of the problem:

1. Check for spilled liquid on the laptop. This is probably the most common reason laptops are donated to Free Geek. There is not much hope for spill victims, and since the extent of the damage cannot be adequately assessed in a reasonable amount of time, the laptop should be recycled. Obvious signs of a spill victim are:
   • sticky keys and/or stains on the keyboard
   • pools of sticky residue under the keyboard, on the logic board, around seams in the casing, and/or in the battery slot
2. Apple power supplies don't have particularly high-quality cables and have a tendency to get frayed. Find a known working power supply and try it on the laptop. If that doesn't work, move on to the next step.
3. As some Apple laptops do not have clear indicators as to whether or not they are on, it can be difficult to tell when are on or not if the internal speakers are disconnected or if the startup chime is disabled in Open Firmware. You should pick up the laptop, press the Power button, and feel for any vibrations. If you can feel something move in the laptop when you do this, it is probably getting power from somewhere. If nothing moves, move on to the next step.
4. Gently shake the laptop. If you can hear something rattling around in there, that's a good indicator that either something snapped off the logic board or someone monkeyed around with it to catastrophic effect. If that's the case, the laptop can get recycled. If you don't hear any rattling, move on to the next step.
5. Apple laptops use Power Management Units (PMUs) to manage power, and occasionally they will flip out and stop working properly. Resetting the PMU will sometimes fix the problem. To learn how to reset the PMU for various models, please follow this link for directions. If that doesn't resolve the problem, move on to the next step.
6. Bad RAM will sometimes prevent a system from starting up. Remove all RAM from the system and trying powering it on. If it does not have any RAM built onto the logic board, it should complain by beeping. If it beeps, try adding different RAM. If there is no change in behavior, replace the RAM and move on to the next step.
7. Find a known working battery for the particular type of laptop you are working on, charge it for a bit in a working laptop, and swap it into the one you are evaluating. If the laptop turns on, odds are the logic board is good but the power connector/DC-in board is bad.

If following these steps does not change the behavior of the laptop, odds are it is irreparably broken and should get recycled.

Laptop turns on, but the display does not work

There are several failure modes laptop displays will fail with, and they are all useful to some degree for diagnosing problems. Among the more common failure modes are, as taken from here:

• partial blanking of the LCD (eg: lower third of screen): probably a bad cable, generally caused by physical damage. However, edge separation of the LCD from its integrated controller board's cabling can also cause this problem. First case requires cable replacement, second requires LCD replacement.

• all-white screen, external display still works: maybe controller failure on the LCD itself, but more likely failed output circuit on the logic board. See my page on the subject here.

• vertical lines: almost certainly failure of contacts at the edge of the LCD itself. Replace LCD.

• dark screen, image faintly visible: failed backlight - either the backlight's power source (inverter) or a failed TTFL bulb in the LCD itself. It's also possible the wiring from the inverter to the LCD have been severed or grounded. Last case can destroy inverter, check wires before replacing inverter.

• dim screen: old backlight bulbs give off less light as they age. Generally the cure is to replace the LCD, but it is possible to replace just the bulb itself though the job is not for the faint of heart.

• moving display causes display issues: usually caused by failing LVDS cable, though LCD edge connection failure can also be the cause. While keeping the entire assembly still, try squeezing the edges of the display gently to see if you can stimulate the problem. If merely squeezing the edge causes it, it's almost certainly an LCD problem.

If the problem is likely to be caused by the LCD panel as opposed to the logic board, there is hope for the laptop.

Booting with an external display

There are a few ways to boot with an external display. This is the process:

1. Turn the laptop off
2. Connect the external display
3. Turn the laptop on while holding the Option key

You should see the Startup Manager display on the external monitor if this works. If it doesn't work, try hitting the Detect Displays button (usually Command - F2, but it may differ for particular models). If it still doesn't work, it's a good indicator that something is very wrong, making this laptop NO GOOD.