Tektronix 744A User Manual

Page of 294
Adjustment Procedures
5–10
TDS 684A, TDS 744A, & TDS 784A Service Manual
CAUTION. Be sure to disable the NVRAM Protection switch as instructed below
to protect the adjustment constants against alteration.
a. Locate the two small access holes on the right side of the oscilloscope
cabinet near the front. (See Figure 5–1.)
b. Insert the adjustment tool (Item 3) in the hole nearest the rear of the
oscilloscope about 1/2 inch to engage the rocker switch.
c.
Push to rock the switch to its protected (disabled) position.
d. To do a complete adjustment as defined on page 5–3, you must also do
the procedure Compensate the Probe on page 5–10 if you are using the
optional P6139A probe.
Probe Adjustment for the P6139A Probe
STOP. It is not necessary to do this procedure to perform a complete adjustment
unless you are using the optional P6139A probe.
This probe adjustment is divided into three parts: Compensate the Probe,
Measure the Probe Bandwidth
, and Adjust the Probe — High Frequency
Response.
 If probe bandwidth is within required limits, you will be instructed to
not do the high frequency response adjustment.
Equipment
Required
One P6139A probe (Item 17).
1. Install the test hookup and preset the oscilloscope controls: 
Compensate the Probe