User Guide

Power Mac G4 Cube Troubleshooting - 3
General Information
Power Adapter Verification
To power on, the computer’s logic board requires a "trickle" power of 28 V. If the system
fails to power on, first reset the PMU. Then follow the procedure below to determine if the
symptom is related to the external power adapter.
Note: To verify the power adapter, you need a volt meter. When connecting the volt meter
leads to specific pins, make sure the power adapter cable remains securely plugged into
its connector on the logic board.
1. Ensure all cards and cables in the computer are securely seated.
2. Ensure a known-good power source and power cord are connected to the power
adapter.
3. Plug the power adapter into the computer.
4. Verify the green LED on the DC-to-DC board is lit as shown below.
The LED on the DC-to-DC board is a good indication the power adapter is
functioning; however, you can further verify the power adapter by checking the
voltage at connector J3 on the video riser card.