Tektronix Type 82 PLUG-IN Instruction Manual page 25

SECTION 4
MAINTENANCE
Visual Inspection
Many potential or existing troubles can be detected by a
visual inspection of the unit. For this reason, a complete
the unit is inoperative, needs repair, or needs recalibration.
Visual defects may include loose or broken connections,
frayed coax-shield that could cause a short, damaged con-
nectors, improperly seated tubes or transistors, scorched or
burned parts, and broken terminal strips.
The remedy for these troubles is readily apparent except
in the case of heat-damaged parts. Damage to parts due
to heat is often the result of other less apparent troubles
in the unit. It is essential that the cause of overheating be
determined and corrected before replacing the damaged
The Type 82 is a stable plug-in unit that will provide many
hours of trouble-free operation. However, to insure the
reliability of measurements, check the calibration of the unit
after each 500-hour period of operation (or every six months
if the unit is used intermittently). A complete step-by-step
procedure for calibrating the unit and checking its operation
is given in the Calibration section of this manual.
COMPONENT REPLACEMENT
General Information
Useful information concerning the replacement of impor-
tant parts in the Type 82 is given in this portion of the
manual, Because of the nature of the unit, replacement of
certain parts such as the V/CM switches, variable capacitors,
nuvistors, transistors or tubes, will require that you recalibrate
the unit to insure proper operation. Refer to the Calibration
section of this manual for the complete procedure.
Switches
If the AC-DC-GND or CHOP RATE switch is defective re-
place the switch. Use normal care in unsoldering and dis-
connecting the leads.
If any of the rotary switches (excluding the AC-DC-GND
switch} are defective, single wafers on these switches are not
normally replaced. If a wafer is defective, the entire switch
should be replaced. The V/CM and GAIN MODE switches
may be ordered from the factory either unwired or wired,
as desired. Refer to the Parts List to find the unwired and
wired switch part numbers. Since the unwired switches re-
When soldering leads to a terminal on a rotary-
type switch, do not let solder flow around and
beyond the rivet on the terminal. Otherwise the
spring tension of the switch contact can be de-
(1) Removing the Attenuator Unit
The attenuator unit contains the VOLTS/CM switch wafers
and attenuator chassis. It can be replaced with a wired unit
ordered through your Field Representative. To remove the
attenuator unit, proceed as follows:
1. Unsolder the output of the attenuator from the grid at
the junction of C126, R126 and R117. Unsolder connections
to AC-DC-GND switch.
2. Use a thin 1" open end wrench to loosen and remove
the nut from the AC-DC-GND switch.
3. Loosen the /14% hex set screw in the VOLTS/CM knob
and remove the knob.
4. Remove the ." nut from the shaft on the front panel
that holds the attenuator unit casting.
5. Remove screws holding the back of the etched circuit
board in place
6. Fold the complete unit back on the etched circuit board
7. Unsolder and unscrew the etched circuit board from the
attenuator chassis at the front of the unit. Do not over-
heat and damage etched circuit board.
8. Remove the attenuator unit by removing the gear on the
shaft of the attenuator. Leave the etched circuit board
in Type 82 chassis.
9. To replace the unit, reverse the order of the preceding
NOTE
The gears which drive the VOLTS/CM switch do
(2) Removing the Etched circuit Board
A replacement wired etched circuit board can be ordered
through your Field Representative. To remove the etched
circuit board, proceed as follows:
a. Remove the attenuator unit as described in 'Removing the
Attenuator Unit".
b. Unsolder all leads on the back of the etched circuit board.
Keep the leads in order so they can be replaced in the
c. Remove the etched circuit board.