Measuring Waveforms
TDS 684A, TDS 744A, & TDS 784A User Manual 3–107
13. Press SHIFT UTILITY ➞ System (main) ➞ Diag/Err (pop-up) ➞ Error
Log (main). If there are too many error messages to be seen on screen, rotate
the general purpose knob clockwise to scroll to the last message.
14. Note the compensation error amount. Skip to step 19.
15. Disconnect the probe from any signal you may have connected it to. Leave
the probe installed on its channel.
16. Press OK Compensate Offset (side).
17. Wait for offset compensation to complete (one to three minutes).
When offset compensation completes, the following occurs:
The clock icon will disappear.
If offset compensation did not complete successfully, you may get the
message “Compensation Error.” This error implies that the probe offset
scale (10% error) and/or offset (50 mV) is too great to be compensated.
You can substitute another probe and continue. Have your probe checked
by service personnel. You can also check the error log by doing steps 13
through 14.
18. After the clock icon is removed, verify the word Initialized changed to Pass
under Cal Probe in the main menu. (See Figure 3–63.)
19. If desired, repeat this procedure beginning at step 1 to compensate for other
probe/channel combinations. But before you do so, be sure you take note of
the following requirements:
Remember to first low frequency compensate any passive probe you
connect (see the prerequisites listed on page 3–105 at the beginning of
this procedure).
Remember to connect all but simple passive probes to the oscilloscope
for a twenty minute warm up before running Probe Cal.
Changing Probes After a Probe Cal. If a Probe Cal has never been performed on
an input channel or if its stored Probe Cal data is erased using the Re-use Probe
Calibration Data menu (discussed later), the oscilloscope displays Initialized
status in its vertical menu. It also displays initialized whenever you remove a
probe from an input.
If you execute a successful Probe Cal on an input channel, the oscilloscope
stores the compensation data it derived in nonvolatile memory. Therefore, this
data is available when you turn the oscilloscope off and back on and when you
change probes.