Apple eMac User Manual

							20 - eMac  Troubleshooting
No Power Symptom Charts
No Power
The computer will not power on.
1. Verify the power outlet is good. Plug a different device into the socket to ensure there is power, or plug 
computer into another outlet.
2. Check the power cord. Use a known good power cord.
3. Check connection of the power cord on both ends. Verify that the plug is securely plugged into both the 
A/C outlet and back of the computer.
4. Remove keyboard, mouse, and other peripherals such as speakers.
5. Position the computer so it rests on the CRT face.
6. Remove the user access door.
7Touch a metal surface inside the computer.   
8 Unplug the unit.
9 Verify the battery is good before replacing modules. A drained battery may be indicative of a 
crashed Power Management Unit. Does the battery measure at least +3.5v? If not, replace 
the battery and reset the PMU. 
10. Reset PMU. Refer to “Resetting the PMU on the Logic Board” mentioned earlier in this chapter. 
						

							eMac  Troubleshooting - 21
No Power Symptom Charts 11. Remove the rear housing.
Warning: This product contains high voltage and a high-vacuum picture tube. To prevent serious injury:
•Review the CRT safety information on Service Source online.
•Discharge the CRT 
•Never use a grounding wriststrap until after discharging the CRT and setting up an ongoing ground 
connection.
12. Check the power button. Attach a known good power button to the unit. Do you have power now? If yes, 
replace the power button. If no, go to the next step.
13. Unplug the unit. Warning: Make sure the ground screw (see below) is attached to the frame when 
testing power. 
						

							22 - eMac  Troubleshooting
No Power Symptom Charts 14. Check the AC connector. Make sure it’s connected. Do you have power now? If yes, test the unit and 
return it to the customer. If no, go to the next step.
15.Warning: Make sure the computer is unplugged. Check the fuse (see graphic below).You will need an 
ohm meter to do a continuity test on the fuse. Using an ohm meter, touch the red and black probes to 
the two metal points at location F901 and check for continuity (reading of “0”). If the ohm meter 
registers “0”, the fuse is good. If the meter registers “infinite”, the display/analog assembly should be 
replaced.  
						

							eMac  Troubleshooting - 23
No Power Symptom Charts 16. Plug the unit in. Check for AC voltage (see below). Warning:  Do not force the probes into the connector. 
Doing so could break the connector. Do you measure 120V (line voltage)? If yes, go on to the next step. 
If no, replace the display/analog assembly. 
17. Make sure the computer is plugged in. Check for 5V trickle on capacitor C3202 (located near the modem 
board) on the logic board (see graphic below). Do you get 5V? If yes, go to the next step. If no, replace 
the display/analog assembly. 
						

							24 - eMac  Troubleshooting
No Power Symptom Charts 18.  Check the down converter connector. Verify that it is properly connected. 
19. Plug the unit in, but don’t press the power button. Check the down converter. Be extremely careful 
when checking voltages. It is easy to short between the pins. Ground to the frame with the black 
probe and check pin 1 on P801 with the red probe. A reading of 10.5V up to 17.5V is acceptable. If you 
get a reading in that range, replace the display/analog assembly. If not, replace the logic board. 
						

							eMac  Troubleshooting - 25
No Power Symptom Charts
Random Shut Down
While using the computer it just shuts down for no reason.
1. Check the jumper settings, make sure they are set correctly. Refer to the “Digital/Analog Voltage Setting 
and LHR Module Instructions” mentioned earlier in this chapter. Note: There is one jumper for the 
voltage and one jumper for the LHR coil. Both jumpers should be installed when the computer is 
operating in the 110V environment. If the jumpers are set correctly, refer to “No Power”.
                                                         Voltage Jumper Location
                                                       LHR Coil Jumper Location 
						

							26 - eMac  Troubleshooting
No Video Symptom Charts
No Video
No video to the internal display, the fan is spinning, there is drive activity
1. Reset parameter RAM. Press Command-Option-P-R during startup.
2. The system software could be damaged. Start up from the system CD that came with the computer.
3. Remove the user access door.
4Touch a metal surface inside the computer.   
5. Disconnect the A/C power cord. Press the PMU reset button on the logic board. Refer to “Resetting the 
PMU on the Logic Board” mentioned earlier in this chapter.
6. Check for external video. Connect an external monitor to the video out port. Did you get external 
video? If yes, replace the display/analog assembly. If no, go on to the next step.
7. Replace the main logic board. 
						

							eMac  Troubleshooting - 27
Vertical Raster Shift Symptom Charts
Vertical Raster Shift 
The raster moves up to the point where the menu bar is no longer visible. Replace the IVAD 
cable (922-5806). Follow the procedure below.
Tools
This procedure requires the following tools:
•2.5 mm hex tool
•Phillips #2 screwdriver
•Hot-melt glue gun (recommended)
•Nylon probe tool (922-5065)
Procedure
1. Remove the rear housing from the eMac.
2.
Discharge the CRT. Warning: This product contains high voltage and a high-vacuum picture tube. To 
prevent injury, review the Service Foundations course: “CRT Displays” for safety information. 
3 . Locate the IVAD assembly shown below.  
						

							28 - eMac  Troubleshooting
Vertical Raster Shift Symptom Charts
4.Note: The screws on IVAD assembly need to be removed to access one end of the IVAD cable. 
Remove the screw (circled below) and then remove the metal cable cover.
5 . Remove the remaining two screws on the IVAD assembly. 
						

							eMac  Troubleshooting - 29
Vertical Raster Shift Symptom Charts
6. With the nylon probe tool or needlenose pliers, remove the glue from the connector. Note: If 
you find it difficult removing the glue use a heat gun to soften the glue a bit and then remove it. 
Disconnect the cable after removing the glue.
7 . Locate the other end of the IVAD cable.