324 Chapter7
General Troubleshooting
Troubleshooting to a Functional Section
Troubleshooting to a Functional Section
1. Refer to Table 7-1 on page 325 for the location of troubleshooting
information.
2. If error messages are displayed, refer to "Error Messages" in this
chapter. You will find both error descriptions and troubleshooting
information.
3. If a signal cannot be seen, and no error messages are displayed, the
fault is probably in the RF Section. Refer to Chapter 12 , “RF
Section.”
4. Blank displays result from problems caused by either the controller
or display/power supply sections. Because error messages 700 to 759
caused by the controller section cannot be seen on a blank display,
use the following BASIC program to read these errors over GPIB. If
the program returns an error code of 0, there are no errors.
10 DIM Err$[128]
20 OUTPUT 718;"ERR?;"
30 ENTER 718; Err$
40 PRINT Err$
50 END
a. If there is no response over GPIB, set an oscilloscope to the
following settings:
Sweep time ................................................... 2ms/div
Amplitude scale .............................................. 1V/div
b. The signals at A2J202 pin 3 and pin 14 should measure about
4 Vp-p. If the levels are incorrect, refer to Chapter 10 and
troubleshoot the A2 controller assembly.
c. Set the oscilloscope to the following settings:
Sweep time ........................................................ 1ms/div
Amplitude scale ................................................... 2V/div
d. The signal at A2J202 pin 15 should consist of TTL pulses. If the
signal is at a constant level (high or low), troubleshoot the A2
controller assembly.
5. Display problems such as intensity or distortion are caused by either
the controller or display/power supply sections. Refer to Chapter
10 or Chapter 13 .
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