12778474-002-2 Revision F – March 2004
TSG-3800 User’s Guide 117
Maintenance and Troubleshooting
Troubleshooting Guidelines
Test Equipment and Tools
Table 4-2
lists test equipment and tools required to perform maintenance and
diagnostics. The frequency reference is only required when checking input signal
accuracy.
During troubleshooting, when a terminal is directly connected to Comm port A or B
and you inadvertently set the mode to Binary, TL1, or Passthru, the CPU will not
respond to typed characters. To exit from TL1 mode, type the Esc key three times.
To exit from Passthru mode, type Alt B. To exit from Binary mode, type the ? key.
When a terminal is directly connected to Comm port A or B and you inadvertently
set the mode of the opposite port to Binary, TL1, or Passthru, use the COMM «port»
ASCII command to return the other port to ASCII mode.
If hardware handshaking is enabled and the CTS line cannot be pulled high, there is
no communication. To correct this, use the other Comm port to turn CTS/RTS
handshaking off. An alternative method is to jumper RTS to CTS on the CPU
module.
Fault Indicators
Most fault lights indicate a hardware failure (for instance, loss of output signal, LOS)
or a detected input signal defect (for example, Out of Frame, OOF). Computed
errors, such as MTIE, can trigger the MAJOR and MINOR indicators.
Chapter 5,
Input Modules
,
Chapter 6, CPU, Frame Generator, and Clock Modules
, and
Chapter 7, Output Modules
describe the indicators on each module.
Error Messages
Error messages are automatically sent to the EIA-232 ports. Each message is date
and time stamped and lists the cause of alarm and any relevant data (for example, a
frequency difference between the active reference and the clock). Appendix B
provides a listing of alarm messages.
Table 4-2. Test Equipment and Usage
Test Equipment
Characteristics
Purpose
Oscilloscope
Dual Trace; 10 MHz sweep
(equivalent to Tektronik #745)
Frequency comparisons; Signal
amplitude measurements
Terminal
Capable of 9600 Baud
Receiving error messages and
entering commands
Frequency
reference
Meeting or exceeding the accuracy
of the signals to be measured
Reference for frequency comparisons
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