Apple eMac User Manual

							10 - eMac  Troubleshooting
 General Information
Power-On Self Test
There is a power-on self test that resides in the ROM of the eMac. This test automatically runs 
whenever the eMac is powered on after being fully shut down (the power-on self test does not 
run if the machine is only restarted).
If a problem is detected during the test, you will not hear a normal startup chime. Instead, the 
system will beep as explained below. Refer to “Error Beeps” later in this chapter for 
instructions on how to troubleshoot and repair an eMac that sounds error beeps at startup time.
Following is a definition of what the error beeps at startup time signify.
One Beep:   No RAM is installed or detected.
Two Beeps: Incompatible memory is installed. (The slots accept standard PC-100 or PC-
133, 168-pin DIMMs). 
Three Beeps: No RAM banks passed memory testing. 
Four or Five Beeps: Bad checksum for the remainder of the boot ROM. The ROM is bad. 
						

							eMac  Troubleshooting - 11
 General Information
Logic Board Battery
Important: Apple highly recommends removing the battery when handling the logic board. Make 
sure to use proper ESD protection when handling modules.
The battery on the logic board controls the stored system settings, such as date and time. It is only 
necessary to test the battery when you can’t power on the computer, or the date and time are reset 
every time the AC power is removed. 
The battery is also used to power the PMU chip (because the PMU chip keeps time and must always 
be running) when the computer is unplugged from the wall (AC power). The PMU is 
very sensitive 
and touching any circuitry that is connected to the PMU can cause it to crash. If the PMU crashes, 
the battery life goes from about five years to about two days if the PMU is not reset. Once the 
battery goes dead, the PMU will reset the time and date every time the AC power is removed. To fix 
this situation, replace the battery and reset the PMU (refer to “Resetting the PMU on the Logic 
Board” mentioned earlier in this chapter).
Testing the Battery
If the computer has a “No Power” situation, check the battery before replacing modules. A drained 
battery may be indicative of a crashed Power Management Unit. 
With the battery in the battery holder (under load), measure the voltage across the battery’s 
positive and ground terminals. 
Does the battery measure at least +3.5v? If not, replace the battery and reset the PMU. If the 
battery does measure over +3.5v, reinstall the battery and reset the PMU as above
Connect the power cord and power up the system again.  
						

							12 - eMac  Troubleshooting
 General Information
Display/Analog Voltage Setting and LHR Module Instructions
The display/analog assembly contains a non-switching power supply which is preset at a 220V 
configuration.The voltage selection needs to be manually set (on the service module) by way of a voltage 
jumper. This means if you are operating the computer in a 110V environment, you will have to install the 
voltage jumper. 
The following instructions explain how to configure the voltage and LHR jumpers on the digital/analog 
assembly. Note: The LHR (a line conditioning module) is required in some international countries.
Refer to Table 1 for jumper settings and refer to Figures1, 2, and 3 for jumper and LHR locations.
Tools
This procedure requires the following tools:
•needlenose pliers to remove/attach the voltage jumper
•phillips #2 screwdriver if attaching the LHR module
 
Table 1: Jumper Settings
Voltage 
EnvironmentVoltage Jumper 
SettingLHR Jumper 
Setting
110 V Jumper is on Jumper is on
220 V 
no LHR moduleJumper is off Jumper is on
220 V 
with LHR moduleJumper is off Jumper is off 
						

							eMac  Troubleshooting - 13
 General Information
Procedure
1. Locate the voltage jumper circled below in Figure 1. Note: this jumper won’t be installed on a 220V 
computer. Next, refer to Table 1 (on the previous page) for the voltage jumper setting and set the jumper 
accordingly. Warning: 
Be careful around the CRT. Discharge the CRT before removing or 
replacing the jumper.
 
                                                         Figure 1: Voltage Jumper Locator
2. Locate the LHR coil jumper circled in Figure 2. Then refer to Table 1 for the LHR jumper setting and set 
the jumper accordingly.
                                                       Figure 2: LHR Jumper Locator 
						

							14 - eMac  Troubleshooting
 General Information 3. Identify if you have the LHR coil (Figure 3) on the eMac. Note: The LHR coil (a line conditioning 
module) is required in some international countries. 
                                                       Figure 3: LHR Module Locator
4.  If y
ou don’t have an LHR module, install the replacement display/analog assembly and ensure the 
jumpers are set correctly.   If you have an LHR, go on to step 5.
5. Remove the LHR from the faulty display/analog assembly, place the LHR on the replacement digital/
analog assembly, and set the jumpers according to Table 1. 
						

							eMac  Troubleshooting - 15
 General Information
Thermal Paste Application
The microprocessor uses a heatsink/thermal pipe to transfer heat away. Whenever the heatsink is removed, 
the bottom side of the heatsink and the top of the microprocessor must be cleaned and thermal paste must 
be applied. If the mating surfaces are not cleaned and thermal paste is not applied, the CPU may overheat 
and become damaged.
Tools
This procedure requires the following tools:
•Plastic stylus or nylon probe tool (922-5065) to remove the old thermal paste
•Thermal paste (922-4757), each tube contains 4-5 applications
Procedure
1. Thoroughly clean the thermal film from the heatsink surface with a plastic stylus or the nylon probe tool. 
Do not use an abrasive material or liquid cleaner. Important: Be e
xtremely careful not to bend the 
heatpipes on the heatsink. 
						

							16 - eMac  Troubleshooting
 General Information 2. Carefully clean the surface of the microprocessor with a plastic stylus or nylon probe tool (922-5065) to 
remove the old thermal paste. 
3.
Squeeze a drop of thermal paste onto the middle of the microprocessor as shown. 
						

							eMac  Troubleshooting - 17
 General Information 4. Spread the paste evenly over the processor. 
5. Reinstall the heatsink. 
						

							18 - eMac  Troubleshooting
 General Information
CRT Neck/Display/Analog Assembly Handling Information
Handling 
Important: It is imperative that proper handling and packaging guidelines be followed when working with 
the display/analog assembly.
Do NOT lift, handle, bump, or manipulate the CRT neck/neck board (see red arrows below) on the Display/
Analog assembly. Modules damaged by mishandling are NOT covered by Apple Warranty. Apple 
Authorized Service Providers can be liable for broken CRT necks due to improper handling. 
Caution: The metal chassis has sharp edges, you may want to wear gloves when handling the assembly. 
Lift the assembly from the metal chassis; never lift the assembly from the neck. I
Packing a Defective Display/Analog Assembly
The packing procedure is included with the replacement display/analog assembly. Incorrect packaging can 
result in damaged eMac displays. Please read and follow the directions enclosed in the shipping box of the 
new display prior to packaging the defective assembly. AASPs can be liable for broken CRT necks due to 
improper packing and handling. 
						

							eMac  Troubleshooting - 19
 Symptom Charts
Symptom Charts
How to Use the Symptom Charts
The Symptom Charts included in this chapter will help you diagnose specific 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 you have replaced a module, reinstall the original module before you proceed to the next cure.
Apple Hardware Test
Apple Hardware Test is a diagnostic tool for detecting problems with Apple internal hardware components 
such as logic board, memory, modem, video RAM, and Apple AirPort Card. The test does not check 
externally connected hardware components such as USB or FireWire devices; it also does not check non-
Apple devices such as third-party PCI cards. 
Note:  The most recent Apple Hardware Test software can be downloaded from the CD Images page on 
AppleCare Service Source; go to the Service Source home page and select ‘Disc Images’ from the quick-
click table.
Error Codes
If Apple Hardware Test detects a problem with a computer, it displays an error code, which is defined in the 
products Error Code List. Consult the list for appropriate repair procedures associated with the code.
All Error Code Lists are included in the Service Diagnostics Matrix, Knowledge Base article 112125. You can 
also access this matrix by clicking the Service Diagnostics rollover link under any of the product areas on the 
Service Source home page.