Apple power mac g4 cube User Manual

							Power Mac G4 Cube Take Apart - 99
 Optical Drive11. Install the screws, but do not tighten until all four are in place. Do not overtighten.
12. Close the AirPort Card door and secure the antenna cable (and AirPort Card).
13. Starting with the two bottom tabs, attach the side panel as shown. Ensure all four tabs 
engage and no cables get caught.
 
14.Important: Ensure the side panel tucks into the chassis.
 
15. Reassemble and test the computer.
Warning: Never turn on the computer unless all of its internal and external 
parts are in place and it is closed. Operating the computer when it is open or 
missing parts can damage the computer or cause injury. 
						

							 
© 2002 Apple Computer, Inc. All rights reserved. 
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Service Source
Troubleshooting
 
Power Mac G4 Cube 
						

							 
Power Mac G4 Cube Troubleshooting -   
1  
 General Information 
General Information
 
Overview
 
This chapter includes symptom charts and other troubleshooting information for this 
computer. Troubleshooting information can also be found online in the Knowledge Base 
link at the Service Source site.  
Resetting the PMU on the Logic Board
 
The PMU (Power Management Unit) is a microcontroller chip that controls all power 
functions for this computer. The PMU is a computer within a computer. Its function is to: 
¥ tell the computer to turn on, turn off, sleep, wake, idle, etc.
¥ manage system resets from various commands.
¥ maintain parameter RAM (PRAM).
¥ manage the real-time clock.  
Important:  
 Be very careful when handling the logic board. The PMU is very sensitive and 
touching the circuitry on the logic board can cause the PMU to crash. If the PMU crashes 
and is not reset, the battery life goes from about Þve years to about two days.
Many system problems can be resolved by resetting the PMU chip. When you have a 
computer that fails to power up, follow this procedure before replacing any modules: 
1. Disconnect the power adapter from the computer and check the battery in the battery 
holder. The battery should read 3.3 to 3.7 volts. If the battery does not have the 
minimum voltage, replace it, wait ten seconds, and then reset the PMU (refer to the 
next step). If the battery is good, go to the next step.  
						

							 
2 -  
Power Mac G4 Cube Troubleshooting
 General Information 2. Press the PMU reset switch (S1) once on the logic board. Make sure the connector J4 
on the video riser card and the video riser card is installed in its connector, then 
proceed to step 3.  
Warning:  
 Do not press the PMU reset switch a second time because it could affect 
the PMU chip. S1 is located on the logic board, under the video card, near the edge 
of the logic board at the end opposite the video ports.
3. Wait ten seconds before connecting the power (adapter) and turning on the computer. 
If the computer turns on, go to the next step. If the computer does not turn on, there is 
something else wrong with the computer. 
4. Use Apple Hardware Test to check the computer.  
Important:  
  This procedure resets the computerÕs PRAM. After resetting the PMU, be sure 
to reset the time, date, and other system parameter settings. 
						

							 
Power Mac G4 Cube Troubleshooting -   
3  
 General Information 
Power Adapter VeriÞcation
 
To power on, the computerÕs logic board requires a trickle power of 28 V. If the system 
fails to power on, Þrst 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 speciÞc 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.  
						

							 
4 -  
Power Mac G4 Cube Troubleshooting
 General Information 5. Locate J3 on the video riser card, and check the voltages from the back of the card as 
shown below. 
6. The voltage should read 28 V (+0.5 V -1 V). Make sure the cable is securely seated in 
connector J3 on the video riser card and at J11 on the logic board. 
The testing is complete. You have just veriÞed that the power adapter is not the cause of 
the No apparent power symptom.  
						

							 
Power Mac G4 Cube Troubleshooting -   
5  
 General Information 
ROM and Processor VeriÞcation: Power-On Self Test
 
The ROM of the Power Mac G4 Cube computer contains a self test that runs whenever the 
computer is turned on after having been shut down. It does not run if the computer is only 
restarted. If a potential issue is detected during the test, you will not hear a startup sound; 
instead, you will see the power-on light ßash two, three, or four times.   
Note:  
 In this case, a ßash is considered to be 1/4 second or 250 ms or greater in length. 
If you do not hear a startup sound, the power-on light will ßash as explained below: 
Two Flashes: No memory is installed or detected
 
If memory is installed, ensure it is seated properly, as follows:
1. Shut down the computer by holding down the power button (about 5 sec.) until it shuts 
off. Then disconnect the power cord from the computer.
2. Remove the computer core.
3. Rotate the core so you can see the memory.
4. Eject and reinsert the memory to ensure the memory is seated properly.
5. After reseating the memory, replace the core in the enclosure.
6. Plug in all the cables, and turn on the computer.
7. If the light still ßashes, contact Apple Support for assistance.
If no memory is installed, install compatible memory, as follows:
8. Shut down the computer by holding down the power button (about 5 sec.) until it shuts 
off. Then remove the power cord from the computer.
9. Remove the computer core.
10. Rotate the core so you can see the memory slots.
11. Install compatible memory. Refer to the Power Mac G4 Cube owners manual, which 
discusses the type of memory that is compatible with the computer. You can also refer 
to http://www.apple.com/guide/, and Knowledge Base article 58776: Power Mac G4 
Cube: Memory SpeciÞcations.
12. After installing memory, reassemble the computer and test for the symptom. 
						

							 
6 -  
Power Mac G4 Cube Troubleshooting
 General Information 
Three Flashes: Incompatible memory types are installed (for example both 
SDRAM and EDO installed)
 
Install compatible memory, as follows:
1. Shut down the computer by holding down the power button (about 5 sec.) until it shuts 
off. Then remove the power cord from the computer.
2. Remove the computer core.
3. Rotate the core so you can see the memory slots.
4. Install compatible memory. Refer to the Power Mac G4 Cube owners manual which 
discusses the type of memory that is compatible with the computer. You can also refer 
to http://www.apple.com/guide/, and Knowledge Base article 58776: Power Mac G4 
Cube: Memory SpeciÞcations.
5. After installing memory, reassemble the computer and test for the symptom. 
Four Flashes: No memory banks passed memory testing
 
Either the memory or the memory slots need replacement, as follows:
1. Shut down the computer by holding down the power button (about 5 sec.) until it shuts 
off. Then remove the power cord from the computer.
2. Remove the computer core.
3. Rotate the core so you can see the memory.
4. Remove all the memory.
5. Check to make sure there are no bent pins in the memory slots. 
						

							 
Power Mac G4 Cube Troubleshooting -   
7  
 General Information6. If there are no bent pins, reset the logic board as follows:
¥ Remove the video card and video riser card from the logic board.
¥ Replace the video riser card back in its slot.
¥ Locate the reset button (S1) on the logic board.
¥ Wait 10 seconds, then press S1 once. Do NOT press the reset button a second 
time.
7. Reinstall memory, and reassemble the computer and test for the symptom.
8. If the light still ßashes, replace the memory modules. 
						

							 
8 -  
Power Mac G4 Cube Troubleshooting
 Symptom Charts 
Symptom Charts
 
How to Use the Symptom Charts
 
The Symptom Charts included in this chapter will help you diagnose speciÞc symptoms 
related to the product. Because cures are listed on the charts in the order of most likely 
solution, try the cures in the order presented. Verify whether or not the product continues 
to exhibit the symptom. If the symptom persists, try the next cure.  
Note: 
  If a cure instructs you to replace a module, reinstall the original module before you 
proceed to the next cure. 
Important: 
  The only way to shut off power completely to the computer and display is to 
disconnect their power plugs from the power source. Make sure the power cords to the 
computer and display are within easy reach.  
Startup
 
No apparent power (no sound and power LED is not lit)
 
1. Verify the power outlet is good.
2. Replace the power cord. 
3. Reset the logic board. Refer to Resetting the PMU on the Logic Board in this 
chapter.
4. Check for trickle voltage on the power adapter connector. Refer to Power Adapter 
VeriÞcation in this chapter. If veriÞcation fails, replace the power adapter.
5. Disconnect external devices, including the monitor, and start up the computer.
6. Remove internal cards and start up the computer.
7. Disconnect internal hard drives from the logic board and start up the computer.
8. Reseat the DC-to-DC board in its connector.
9. Check the modem connector. If the connector has any bent pins, replace the logic 
board.
10. Replace the logic board.