Tektronix 114, Instruction Manual, Page: 17 / 50

Maintenance and Calibration — Type 114
3. If the voltage and resistance measurements taken in
the proceeding steps are normal, use an oscilloscope to
check the waveforms at the points shown on the schematics
in Section 5. Checking the waveforms will help in isolat ­
ing the trouble to a particular circuit. Once the trouble is
isolated to a particular circuit, take voltage and resistance
measurements until the defective component is identified.
Component Identification. The circuit number of each
electrical part is shown on the circuit diagrams in Section 5.
Note that a functional group of circuits (such as the power
supply) is assigned a particular series of numbers. Switch
wafers are identified by counting from the first wafer locat­
ed behind the detent section of the switch towards the last
wafer. The letters F and R indicate whether the front or
rear of the wafer is used to perform the particular switch ­
ing function. For example, the designation 2R printed by a
switch section on a schematic identifies the switch section
as being on the rear side of the second wafer when counting
back from the detent section.
Parts Replacement. Most of the electronic components
in the Type 114 are standard items available locally. The
remainder of the electronic components and most of the
mechanical parts are manufactured or selected by Tek-
tronix to satisfy particular requirements, or are manufac ­
tured for Tektronix to our specifications. However, all parts
are obtainable through your Tektronix Field Engineer or
Field Office. Before purchasing or ordering, consult the
Parts List (Section 5) to determine the value, tolerance, and
ratings required. See “ Parts Ordering Information" and
"Special Notes and Symbols" on the first page of Sec ­
tion 5.
When selecting the replacement parts, it is important
to remember that the physical size and shape of a com ­
ponent may affect its performance in the circuit. Parts
orientation and lead dress should duplicate those of the
original part, since many of the components are mounted
in a particular way to reduce or control stray capacitance
and inductance. After repair, portions of the instrument may
require recalibration.
Replacing Components on Etched-Circuit Boards. Use
ordinary electronic grade 60/40 solder and a 35- to 40-
watt pencil soldering iron with a '/ 8 " wide chisel tip. The
tip of the iron should be clean and properly tinned for best
heat transfer in a short time to a soldered connection. A
higher wattage soldering iron, if used and applied for too
long a time, ruins the bond between the etched wiring and
base material by charring the glass epoxy laminate.
The step-by-step technique is as follows:
1. Remove the component by cutting the leads near the
body. This frees the leads for individual unsoldering.
2. Grip the lead with needle-nose pliers. Apply the tinned
tip of a 40-watt pencil soldering iron to the lead between
the pliers and the board; then pull gently.
3. When the solder first begins to melt, the lead will
come out, leaving a clean hole. If the hole is not clean,
use the soldering iron and a toothpick or a piece of enamel
wire to open the terminal hole. Do not attempt to drill the
solder out since the "through-hole" plating might be de­
stroyed.
4. Clean the leads on the new component and bend
them to the correct shape. Carefully insert the leads into
the holes from which the defective component was removed.
5. Apply the iron for a short time at each connection on
the side of the board opposite the component to properly
seat the component.
6. Apply the iron and a little solder to the connections
to finish the solder joint.
Calibration and Verification
Recalibrate the Type 114 after each 500 hours of opera ­
tion, or every six months if used intermittently. It may also
be necessary to recalibrate certain sections of the instru ­
ment when transistors or other components are replaced.
Before recalibrating the instrument, clean it as previously
described.
Do not preset the internal adjustments as a preliminary
to recalibration. Presetting internal adjustments makes it
necessary to completely recalibrate the instrument.
The following portion of this manual presents a step-by-
step calibration and verification procedure. The title of each
numbered step begins either with "Adjust" or
"Check", thereby identifying the step function as calibra­
tion or verification. The steps are identified in this manner
because any or all groups of numbered "Checks" can be
skipped without disrupting the continuity of the procedure.
However, all adjustments must be completed in the order
given and none should be skipped. Remember that proper
overall operation is ensured only when all steps in the pro­
cedure have been completed and all adjustments have
been made as accurately as possible.
NOTE
The performance standards described in this sec­
tion of the manual are provided strictly as guides
to calibration of the Type 114 and should not be
construed as advertised performance specifica ­
tions. However, if the Type 114 performs within
the guide tolerances given in the calibration pro ­
cedure, it will also perform as listed in the Char ­
acteristics section of this manual.
Equipment Required. (See Fig. 4-1.)
1. Oscilloscope, Tektronix Type 547/1 Al or equivalent.
2. Time mark generator, Tektronix Type 180A or equiv ­
alent.
3. Volt-Ohm-Milliammeter, 20,000 Ω per volt, Simpson
Model 260 or equivalent.
4. Three 50 Ω coax cables with BNC connectors (Tek­
tronix Part No. 012-057).
5. 50 Ω BNC termination (Tektronix Part No. 011-049).
6. Variable line voltage source such as a variable auto­
transformer.
4-3