Tektronix 1502C Telescope User Manual


 
Operating Instructions
110
1502C MTDR User Manual
ii. Noise Diagnostic measures the internal RMS noise levels of the
instrument.
iii. Offset/Gain Diagnostic reports out-of-tolerance steps in the program-
mable gain stage. This can help a service technician to quickly isolate
the cause of waveform distortion problems.
iv. RAM/ROM Diagnostics Menu performs tests on the RAM (Random
Access Memory) and the ROM (Read Only Memory).
v. Timebase Is: Normal - Auto Correction / Diagnostic - No
Correction. When in Normal - Auto Correction, the instrument
compensates for variations in temperature and voltage. This condition
might not be desirable while calibrating the instrument. While in
Diagnostic - No Correction, the circuits will not correct for these
variations.
b. Front Panel Diagnostics aids in testing the front panel.
c. LCD Diagnostics Menu has these choices:
i. LCD Alignment Diagnostic generates a dot pattern of every other
pixel on the LCD. These pixels can be alternated to test the LCD.
ii. Response Time Diagnostic generates alternate squares of dark and
light, reversing their order. This tests the response time of the LCD and
can give an indication of the effectiveness of the LCD heater in a cold
environment.
iii. LCD Drive Test Diagnostic generates a moving vertical bar pattern
across the LCD.
iv. Contrast Adjust allows you to adjust the contrast of the LCD. It
generates an alternating four-pixel pattern. The nominal contrast is set
internally. When in Contrast Adjust mode, VERT SCALE is used as the
contrast adjustment control. This value ranges from 0 to 255 units and
is used by the processor to evaluate and correct circuit variations caused
by temperature changes in the environment. When the diagnostic menu
is exited, the LCD contrast returns to that set by internal adjust.
d. Chart Diagnostics Menu offers various tests for the optional chart
recorder.
i. LCD Chart allows adjusting the number of dots per segment and the
number of prints (strikes) per segment.
ii. Head Alignment Chart generates a pattern to allow mechanical
alignment of the optional chart recorder.