Tektronix 2236, Instruction Manual

Page: 103 / 350

Section 5— 2236 Service
ADJUSTMENT PROCEDURE
INTRODUCTION
PURPOSE
The “Adjustment Procedure’ is a set of logically se­
quenced instructions intended to return the instrument to
conformance with the Performance Requirement state­
ments listed in Table 1 -1. Adjustments contained in this pro­
cedure should only be performed after checks from the
“Performance Check Procedure” (Section 4) have indicated
a need for readjustment or after repairs have been made to
the instrument.
STRUCTURE
This procedure is structured into four major subsections,
each of which can be performed independently to permit
adjustment of individual sections of the instrument. For ex­
ample, if only the Vertical section fails to meet the Perfor­
mance Requirements or has had repairs made, it can be
readjusted with little or no effect on other sections of the
instrument.
The Power Supply section, however, affects all other
sections of the instrument. Therefore, if repairs or readjust­
ments have been made that change the absolute value of
any of the supply voltages, the entire Adjustment Procedure
should be performed.
At the beginning of each subsection is a list of all the
front-panel control settings required to prepare the instru­
ment for performing Step 1 in that subsection. Each suc­
ceeding step within a subsection should be performed in
sequence and in its entirety to ensure that control settings
will be correct for ensuing steps. All steps within a subsec­
tion should be completed.
TEST EQUIPMENT
The test equipment listed in Table 4-1 is a complete list of
the equipment required to accomplish both the “Perfor­
mance Check Procedure” in section 4 and the “Adjustment
Procedure” in this section. To assure accurate measure­
ments, it is important that test equipment used for making
these checks meet or exceed the specifications described in
Table 4-1. When considering use of equipment other than
that recommended, utilize the ‘ Minimum Specification’ col­
umn to determine whether available test equipment will
suffice.
Detailed operating instructions for test equipment are not
given in this procedure. If more operating information is re­
quired, refer to the appropriate test-equipment instruction
manual.
LIMITS AND TOLERANCES
The limits and tolerances stated in this procedure are
instrument specifications only if they are listed in the ‘ Per­
formance Requirements’ column of Table 1-1. Tolerances
given are applicable only to the instrument undergoing ad­
justment and do not include test-equipment error. Adjust­
ment of the instrument must be accomplished at an ambient
temperature between + 18°C and +28°C , and the instru­
ment must have had a warm-up period of at least 30
minutes.
ADJUSTMENT INTERACTION
Some adjustments interact with and affect other adjust­
ment settings. Table 5-1 identifies these interaction areas.
Refer to this table if a partial procedure is performed or if a
circuit requires readjustment due to a component replace­
ment. To use Table 5-1, first find the adjustment that was
made (extreme left column). Then move to the right, across
the row, until you come to a darkened square. From the
darkened square, move up the column to find the interactive
adjustment. Check the accuracy and, if necessary, readjust
the adjustment.
PREPARATION FOR ADJUSTMENT
The instrument cabinet must be removed to perform the
Adjustment Procedure. See the “Cabinet” removal and re­
placement instructions located in the “Maintenance” section
of the manual. When making some adjustments in the oscil­
loscope section of the instrument, the CTM circuit board
has to be lifted up and latched to allow access to the adjust­
ments. See the “CTM Circuit Board” procedure in the
“Maintenance” section.
5-1