Maintenance And Troubleshooting - Symmetricom XLi User Manual

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The data transmitted is in a user selectable format as follows (the actual string length is too long to place
on a single line of type, so it is broken into two lines here):
<stx>AAAdd.mmm<cr><lf>BBBsd.mmm<cr><lf>CCCsdd.mmm<cr><lf>
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DDDHH MM SS.mmm<cr><lf>EEEDDD HH MM SS<tqf><cr><lf><etx>
AAA, BBB, CCC, DDD, and EEE represent the three-digit addresses for System Frequency, Frequency
Deviation, Time Deviation, System Time, and Local Time, respectively. The lower case 's' represents the
sign (±), lower case 'dd' and 'd' is the decimal portion of the value represented, and 'mmm' represents
the fractional portion of the value represented.
Addresses entered with a negative value aren't transmitted from the Display Port. Thus, if a non-
addressable display is to be used, setting only one address positive causes that associated data to be
transmitted alone.
Up to 10 displays may be connected to the RS-422 port in a multi-drop configuration.

Maintenance and Troubleshooting

This option has been designed to provide maintenance-free operation and requires no periodic servicing
or calibration. There are no user serviceable components in the FTM card. A qualified service technician
may replace the surge protection fuse (pig-tail solder type) if it is determined to be faulty.
Warning:
Only a qualified technician should attempt troubleshooting of this option. Dangerous
voltages are present which can cause electric shock that could result in severe injury
or death.
Before proceeding, see "Operation" on page 196 for a description of normal operation and user
configurations. Sometimes an apparent failure may simply be an incorrect user configuration entry (e.g.,
50 Hz instead of 60 Hz).
• Ensure the FTM card configuration is correct.
• Ensure that the line voltage to be measured is in the range of 95 - 260 VAC and that the power
cord is properly seated into the AC line connector of the FTM card rear panel (not the line cord
used for XLi power).
• If Frequency Deviation is reading "-9 " and Time Deviation is incrementing 1 second/second, then
the problem might be that no line voltage signal is reaching U6 pin 41.
• Turn off the power to the XLi and remove the power connector to the FTM card.
• Unscrew the securing screws and remove the lid of the XLi.
• Use static sensitive component handling procedures when handling the FTM PCB.
• Install the FTM card board back into the XLi and replace the four rear panel retaining screws.
• Replace the XLi lid and retaining screws.
• Replace the line cord into the FTM rear panel and re-apply power to the XLi. If Frequency
Deviation is reading "-9 " and Time Deviation continues to increment 1 second/second, then the
FTM must be sent back to the factory for repair. If any "event" occurred coincidentally to a failure
of the option, please relate the event to the factory. The information may be useful in repairing the
option, and allow for improvements in the design of the FTM card.
• If no information is being transmitted from the FTM RS-422 Display Port, ensure that the baud
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XLi Time & Frequency System
XLi-man, Issue 8, 6/17/2008, Rev. H
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