The Power Mac G4 computer screen is black. The boot tone is not present, the drive does not operate, but the fan is running, and LED is lit.

This article covers repair procedures for authorized service providers on selected Apple products, but we have published them in the Knowledge Base for the general public for educational purposes. At this time, there are a limited number of repairs that a customer can perform and these are covered under the customer installable parts program http://www.info.apple.com/installparts . If you have not been authorized to perform these procedures, please contact Apple (800-APL-CARE in the USA) or your local authorized service provider to schedule a repair.

Symptom

The Power Mac G4 computer screen is black. The boot tone is not present, the drive does not operate, the fan is running, and LED is lit.

Affected Products

• Power Mac G4
• Macintosh Server G4
• Macintosh Server G4 with Mac OS X Server

DANGER! This procedure exposes you to high voltages that can result in death or serious injury. DO NOT ATTEMPT THIS PROCEDURE IF YOU HAVE NOT BEEN CERTIFIED AS AN APPLE-AUTHORIZED TECHNICIAN.

1. Power Mac G4 (PCI Graphics): Check jumper block at J25. Make sure jumper is correct color for processor type, includes all required inner metal clips, and is installed in correct direction. See "Processor Module" in Service Source Take Apart for more information.

2. Check video cable/card connections.

3. Reset the Cuda chip. Refer to article 95065: " Power Macintosh G4 (PCI Graphics): Resetting the Cuda Chip"

4. Reset the logic board. Power Mac G4 (AGP Graphics): Refer to resetting the PMU in article 95037: " Power Mac G4 (AGP Graphics/Gigabit Ethernet): Resetting the PMU on the Logic Board ". If you have a Power Macintosh G4 (PCI Graphics): Refer to article 95066: " Power Macintosh G4 (PCI Graphics): Resetting the Logic Board" .

5. Reseat video card.

6. Reseat SDRAM DIMMs. Make sure DIMMs are PC-100 DIMMs.

7. Reseat the processor module.

8. Remove all SDRAM DIMMs and try replacing them one at a time to test. Replace any bad DIMMs.

9. Replace video card.

10. Replace processor module.

11. Replace logic board.

12. Replace the power supply.