Fine Dac; Spare Gain; Prb Coarse; Prb Fine - Tektronix 11A52 Service Manual

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Diagnostics
Test Failure
Test failure may be caused by problems in the passive circuitry for the offset signal.
FINE DAC
This routine checks the offset scaling error of the fine offset calconstants.
It
generates a percentage error of the
characterized fine offset scaling versus the expected nominal fine offset scaling. If the calculated error exceeds
±2%, the test is flagged as failed.
Test Failure
Test failure may be caused by problems in the passive circuitry for the offset signal.
SPARE GAIN
This routine examines the spare gain calconstant to ensure that the highest-characterized gain is in the linear
region of the M377's varigain range.
Test Failure
1 est failure indicates a problem with the output amplifier (M377) ICs.
PRB COARSE
This routine checks the error in the scaling of the probe coarse offset. The test produces meaningful results only
when a Level 2 offsettable probe is connected, and has been run through a probe calibration cycle. The test
generates a percentage error in the scaling of the probe coarse offset by forming a ratio of the characterized
probe coarse offset scaling versus an expected ideal scaling factor. If the error exceeds ±3%, the test is flagged
as failed.
Test Failure
Failures here may be caused by a faulty probe, bad probe-to-amplifier connection, amplifier signal path
problems, or by a faulty probe coarse offset ACVS channel.
PRB FINE
This routine checks the error in the scaling of the probe fine offset. The test produces meaningful results only
when a Level 2 offsettable probe is connected, and has been run through a probe calibration cycle. The test
generates a percentage error in the scaling of the probe fine offset by forming a ratio of the characterized probe
fine offset scaling versus an expected ideal scaling factor. If the error exceeds ±3%, the test is flagged as failed.
11A52 Extended Service Manual 4-15