Skip to main content

Power On Self Test (POST) in iMac 21.5 inch, 2009

Intel-based Mac computers such as the iMac rely on a combination of tones to indicate Power

On Self Test (POST) error codes.

• If the computer detects out-of-specification or no SDRAM, the screen will remain black
but the computer will beep. This error condition may be due to physically damaged RAM,
installing incorrect type of RAM, or not having RAM installed.

• Some RAM may appear to pass the Power-On-Self-Test (POST) but still cannot be used by
the operating system. In this case, the computer will display a gray screen, sound three
tones and repeat tones until computer is turned off.

• The solution to both of these situations is to first re-seat memory and test computer again.
If memory fails POST again, remove all installed memory and test by installing one by one
each memory module that has been verified to work correctly on another system (i.e.,
“known-good”) or order new memory.

• A sequence of tones heard at startup or a no video symptom may also be fixed by
temporarily removing/replacing the backup battery.
Labels:

Comments

Post a Comment

Popular posts from this blog

Run Apple Service Error Diagnostic

Run Apple Service Error Diagnostic  Run Apple Service Diagnostic version 3S135 to determine if any thermal sensors or blowers are malfunctioning. If ASD is not available, run Apple Hardware Test version 3A189 by holding down the D key during startup. When a test reports an error, reseat appropriate connections. If issue persists, replace the corresponding part (sensor, blower, logic board, video card, or power supply). See Apple Hardware Error code chart below for correlation between error code, affected sensor, sensor location, and additional checks to perform. AHT Error code Suspected part and Location Suggested Action Notes 4SNS/1/C0000008: TA0P - xxx mbient temp sensor damaged or disconnected from logic board. Verify sensor cable is securely connected to the top edge of the logic board and attached to the left speaker housing. Replace sensor cable if damaged. All fans ramp at full speed if sensor is disconnected. 4SNS/1/C0000008: T00p-xxx ODD temp sensor dama
Post a Comment
Read more

How to Troubleshoot wireless mouse and keyboard issues

If your Apple wireless mouse, keyboard, or trackpad aren‘t working as expected Try these steps to fix issues with your Apple wireless mouse, keyboard, or trackpad. Your device isn't recognized by your Mac Your mouse, keyboard, or trackpad intermittently stops responding Your mouse doesn't scroll up or down or side to side Your mouse or trackpad doesn't track as expected Your keyboard has one or more keys that don't respond Your device isn't recognized by your Mac Follow these steps if your mouse, keyboard, or trackpad isn't recognized by your Mac. Make sure that your wireless mouse, keyboard, or trackpad is turned on The Magic Mouse and Magic Mouse 2 have a slide switch on the bottom of the device. Slide the switch to turn on the device. On the Magic Mouse, the green LED briefly lights up. On the Magic Mouse 2, green coloring is visible beneath the switch. The Magic Keyboard and Magic Trackpad 2 have a slide switch on the ba
Post a Comment
Read more

how to LED Startup Sequence in iMac 2015

LED #1 = Power available. If no LED is visible: • Verify AC source • Verify known-good AC cable is connected • Verify cable connection between AC inlet and power supply • Verify cable connection between power supply and logic board • Verify power supply LED #1 + LED #2 = Power available, and system is powered on. If second LED is not visible when power button is pressed: • Verify power button connection to logic board • Verify power button functionality • Verify cable connection between power supply and logic board • Verify power supply • Verify logic board LED #1 + LED #2 + LED #3 = Power available, system is powered on, and video card found . If third LED is not visible after power on: • Verify that MXM video card is seated properly • Verify logic board LED #1 + LED #2 + LED #3 + LED #4 = Power available, system is powered on, video card found, and internal LCD found. If fourth LED is not visible after power on: • Verify cable connections between LCD pane
Post a Comment
Read more