Networking TIC

Network Devices - LANplex 2500 Troubleshooting

• Overview - 3Com Technical Support
• Diagnosing Problems
• Related Maintenance Procedures
• Table : Troubleshooting Power Failures
• Table : Troubleshooting Abnormal System Processor LED Activity
• Table : Troubleshooting Abnormal Module LED Activity

Overview - 3Com Technical Support

This section describes how to troubleshoot specific problems, such as no system power or abnormal LED activity. This section shows you how to:
- Identify and correct system problems
- Perform related diagnostic tasks, such as replacing fuses or cleaning fiber optic cables

Diagnosing Problems

By observing system diagnostics, you can identify and correct problems ar system power up.

Power Failures

If the system does not respond during power up, See "Troubleshooting Power Failures."

Abnormal LED Activity

The system procesor contains several status LEDs to indicate system problems. Also each option module has status LEDs that alert you to problems with a module or port. See "Troubleshooting Abnormal System Processor LED Activity" or "Troubleshooting Abnormal Module LED Activity" for troubleshooting suggestions in the event of abnormal LED activity on either the system processor or an option module.

CAUTION: When handling modules, always use a wrist strap that is connected to a proper ground. This prevents the module from being damaged by electrostatic discharge.

Related Maintenance Procedures

During system troubleshooting, you may have to perform minor maintenance procedures to correct the problem. These maintenance procedures are described below. For assistance not described below, contact 3Com Technical Support.

Checking the LANplex System Fuses

If the LANplex System does not power up, you may want to check the fuses. Two fuses are located inside the AC power switch assembly on the rear of the chassis. The fuses are mounted in removable cartridges.

WARNING: Before beginning this procedure, power down and unplug the system to prevent electric shock and / or sytem damage.

You need a small, flat-blade screwdriver to complete this procedure.

Removing the Fuse:

To remove the fuse, follow the following steps:

1. Insert a small flat blade screwdriver into the slot at the top of the power switch assembly and flip open the hinged panel covering the fuse cartridges.
   
   
   Accessing the AC Power Fuses
   
2. Release the fuse cartridge by gently pushing on the cartridge in the direction of the arrow until the fuse cartridge is released.
3. Remove the fuse cartridge from the fuseholder.
   
   
   Removing / Replacing the AC Power Fuses
   
4. Pull the fuse out of the cartridge and inspect the wire. If the wire is broken, install a new fuse.

Installing a New Fuse:

To install a new fuse:

1. Insert the new 4-amp fuse into the cartridge. See the above figure.
   
   CAUTION: For continued protection against file hazard, replace the fuses with fuses of the same type and rating. Using an incorrect fuse can subject your system to overcurrent conditions, resulting in damage or unsafe operating conditions.
   
2. Reinstall the fuseholder cartridge into the power switch assembly.
3. Close the panel covering the fuseholder cartridge.
4. Ensure that the power switch is in the off position. Plug the appropriate end of the power cord into the power supply receptacle and the other end into the power outlet.
5. Power on the system.

Cleaning Dirty Fiber Optic Cables

Fiber optic transceivers are sensitive optical devices that need to be handled carefully. If dirt collects on the fiber optic lens, you may notice that the LED for an FDDI port either does not light or lights yellow. You may also notice degradation in port performance, indicated by an increase in the Link Error Rate (LER) count for that port.

To prevent dust from collecting on the fiber optic lens, keep dust covers on the ports at all times when not in use. To clean a fiber optic lens, follow the pocedure below:

1. Remove any accumulated dust or debris from the port or connector by blowing off all surfaces with a canned air duster. Compressed gas is recommended, such as Chemtronic's Untrajetâ or the Triangle Tool Group's Liqui-Toolä Dust-A-Way. Do not use commercial compressed air or "house air" because of the risk of oil contamination.
2. Reconnect the cable to the port to see if the dusting corrected the problem.
   If the LED still does not light, or if it lights yellow, continue with steps 3 and 4.
3. Gently wipe the ports with a lint-free, nonabrasive, nonadhesive swab. Microswabsä by Texwipeä are recommended.
4. Gently wipe the connectors with a lint-free, nonabrasive wipe or pad. Texwipe pads are recommended.
   Avoid touching all surfaces after cleaning the connectors, and keep all unusedports covered.

Troubleshooting Power Failures

Troubleshooting Abnormal System Processor LED Activity

Troubleshooting Abnormal Module LED Activity