Self Tests - Tektronix 11A52 Service Manual

Diagnostics
Self-Tests
After the amplifier has successfully powered up, initialized its settings, and established communication with
the oscilloscope, the oscilloscope requests that the amplifier execute its self-test routines (unless the
oscilloscope's self-tests have been disabled, in which case all self-tests will be skipped) by sending the
message TEST BEGIN to the amplifier. At this point, the amplifier starts executing self-test routines that
require no oscilloscope resources (Calibrated Voltage Reference or Measurement System). The following self-
test routines are executed:
• RELAY DRVR-Attenuator Driver Test
•
PROBECODE~heck
for Stable Probecode
• CKSM PLUG-Check Signal Path Calconstant Checksum
• CKSM PROBE-Check Probe Calconstant Checksum
• ADC TEST-Test Analog to Digital Converter
• FUSE TEST-Check Probe Power Fuses
• ACVS TEST-Test Analog Control Voltage System
• Check Calconstants for Channel 1
• Check Calconstants for Channel 2
For descriptions of each of the tests, refer to the Diagnostics part of this section.
Each test is run in turn, starting with the Attenuator Driver Test. If any of the test routines return a failure
indication, the area and routine number of the failing routine are saved (First Failed Area/Routine), and a
block of descriptive information relating to the failure is stored in the amplifier for later retrieval by the
oscilloscope (via the DIAG CONFIG command). All of the tests are executed, regardless of their exit status.
When all tests are complete, a TEST STATUS message is sent to the oscilloscope indicating
a) all tests passed, or
r)
the Area and Routine number of the first routine that failed.
If large numbers of tests failed, the amplifier, which has limited storage resources, saves as much failure
information as possible. (The number of failure information blocks that may be stored in the amplifier varies,
depending on the types of failures involved; any 'overflow' failure information is discarded.)
After running the tests that require no oscilloscope resources, the oscilloscope requests that the amplifier
execute the remaining self-test routines which require oscilloscope resources, by sending the command TEST
COMPLETE. Upon receipt of this command, the amplifier performs a series of tests that use the oscilloscope's
Calibrated Voltage Reference (CVR), and the oscilloscope's measurement system. The following tests are
executed:
• Gain Off
• Gain On
These tests are executed in the same manner as the preceding tests which do not require oscilloscope resources,
with each test executing in turn.
If
a failure is found, failure information blocks are stored in the amplifier for
later retrieval by the oscilloscope. For more information on the specific functioning of these tests, refer to the
Diagnostics part of this section. When the tests are complete, the amplifier will report their success or failure
with a TEST STATUS message. .
4-4 11AS2 Extended Service Manual