Mainframe troubleshooting
Table 2-4: Mainframe troubleshooting procedures (cont.)
Problem Troubleshooting steps
Fan not working
Run diagnostics and check the fan voltage:
If the 5 V for the fan is not present, replace fuse F 1 on the Main board or replace the
Main board.
If the 5 V for the fuse is OK, the replace the fan. If that does not fix the problem, then
replace the LAN/Fan board.
Instrument not able to genlock
Adjust/check the master clock. (See page 2-2, Mainframe clock adjustment.) After adjustment,
go into the mainframe diagnostics and verify that the CAL value readout is less than ±2.5e–6.
If not then replace the oven or the Main board.
In Factory mode, run the PLL Range Check from the mainframe diagnostics (perform the
common diagnostic tests in the TG8000 Specifications and Performance Verification Technical
Reference manual. Verify that all the secondary clocks can tune at least ±90e -6. If not,
then replace the Main board.
Display problems
On power up, the LCD display should initially be dark but have a visible set of black squares on
the top row. After a second or two, the LCD backlight should come on and a booting message
should appear. If the backlight does not come on, check fuse F700 on the Main board, and
then replace the display. If the text is not there, replace the display, then the cable, and finally
the Main board if necessary.
Keyboard/front panel problems On power up, the front panel buttons and indicators should light up in groups of 3 to 5. This
sequence will repeat about 4 times while waiting for the instrument to boot. The flashing
sequence is controlled by the front panel, only power is required from the Main board. So if
there flashing does not occur then replace the front panel.
Note that the new front panel will not flash until the mainframe software has fully booted and
loaded the code into the front panel. After the system has booted, go to the mainframe utilities
and run the keyboard diagnostic to check all the keys, if this does not pass, replace the Key
board, then the cable, and if still bad then replace the Main board.
Remote interface problems Use the UTILITY menu to verify that the GPI alarm output is enabled and that the desired
error c onditions are also enabled.
Module(s) not working properly Use a GPS7 module to run the I/O slot tests. (See page 2-12, I/O slot tests.)
TG8000 Multiformat Test Signal Generator Service Manual 2–17
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