Operating Instructions
1502C MTDR Service Manual
1–9
5. Diagnostics Menu lists an extensive selection of diagnostics to test the
operation of the instrument.
NOTE. The Diagnostics Menu is intended for instrument repair and calibration.
Proper instrument setup is important for correct diagnostics results. Refer to the
1502C Service Manual for more information on diagnostics.
a. Service Diagnostics Menu has these choices:
i. Sampling Efficiency Diagnostic displays a continuous efficiency
diagnostic of the sampling circuits.
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
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