Measuring Waveforms
TDS 684A, TDS 744A, & TDS 784A User Manual 3–105
NOTE. Probe Cal is not recommended with the P6139A passive probe. This
probe typically has little gain and offset error, and therefore, the improvement in
performance after a Probe Cal is not worth the time needed to do the Probe Cal.
Probe Cal makes significant performance improvements when performed with
active probes or older passive probes.
To run a probe cal, follow the instructions regarding prerequisites below and then
do the steps that follow:
If you are installing an active probe, such as the P6245, there are no
prerequisites to performing this procedure. Start at step 1.
If you are compensating for a passive probe with this procedure you must
first compensate the low frequency response of the probe. First, do steps 1
and 2 below, and then compensate the probe by following the instructions
that came with your probe. (Or see To Compensate Passive Probes on
page 3–3.) Then continue with step 3 of this procedure.
1. Install the probe on the input channel on which it is to be used.
2. Power on the digitizing oscilloscope and allow a 20 minute warm-up before
doing this procedure.
3. Press SHIFT UTILITY ➞ System (main) ➞ Cal (pop-up).
4. Look at the status label under Signal Path in the main menu. If the status
does not read Pass, perform a signal path compensation (Signal Path
Compensation, page 3–102), and then continue with this procedure.
5. Press the front-panel button corresponding to the input channel on which you
installed the probe.
6. Press VERTICAL MENU ➞ Cal Probe (main).
STOP. Your oscilloscope will detect the type of probe you have installed and
display screen messages and menu choices for compensation of probe gain,
offset, or both. (See Figure 3–63.) The following steps will have you run probe
gain, offset, or both depending on the probe the oscilloscope detects.
7. If the message on screen is Probe Offset Compensation rather than Probe
Gain Compensation, skip to step 15.
8. Connect the probe tip to PROBE COMPENSATION SIGNAL; connect
the probe ground lead to PROBE COMPENSATION GND.
9. Press OK Compensate Gain (side).
10. Wait for gain compensation to complete (one to three minutes).