Tektronix 1A5 Instruction Manual page 51

Maintenance — Type 1A5
uator switches Unsolder the shield straps of the 2 Coupling
capacitors (C 1 01 and C201) from the INPUT connector ter ­
minals. Disconnect the two shielded leads which straddle the
rear of the switch assembly and disconnect the 4 square-pin
connectors from the Output Amplifier board.
put Amplifier board, disconnect the 2 square-pin connectors
which lead to the Attenuator section. Remove the 4 screws
form the Output Amplifier board. Remove the cable clamp
from the rear of the attenuator housing by removing one
screw.
Pull the AC-GND-DC switch knobs off. Note the position
of the VOLTS/CM knobs and then remove them. These knobs
pull directly off the front of the shaft after 2 set screws in
each knob are loosened. Remove the nut and washer from
the front of the switch assembly shaft. Remove the nut from
the rear of the front panel Ground terminal. Remove the
nuts from the rear of the INPUT connectors and then re ­
move the connectors. Remove the 2 chassis mounting screws
from the rear of the switch assembly. The attenuator and
switch assembly is now free.
Raise the Output Amplifier board and slide the switch and
attenuator assembly toward the rear of the chassis until
the front is free. Then lift the assembly out of the chassis,
front first.
Replacement Procedure. If sections of the switch mechanism
were switched independent of the rest of the unit while
disassembled, the switches must be re-aligned to each other.
Use the VOLTS/CM Switching schematic as a guide. Before
4-14
replacing the switch, loosen the four screws on the mounting
plate between the Attenuator housing and the rear switch
section. This will allow the parts to slip enough to align them ­
selves during assembly.
At the In ­
Insert the Attenuator and Switch assembly in the chassis
by reversing the removal procedure. Replace and tighten the
INPUT Connector washers and nuts.
the washer and nut on the front of the Switch and Atten ­
uator assembly shaft. Replace and tighten the front panel
ground post. Replace the two chassis screws in the mount ­
ing plate between the attenuator housing and rear switch
section. Draw the mounting plate down to the chassis, but do
not tighten screws. Tighten the 4 screws located on the
mounting plate between the attenuator housing and the rear
switch section, allowing the rear switch section to align it ­
self with the front of the assembly. Tighten the 2 chassis
mounting screws which were previously inserted.
Resolder the following connections: 2 coupling capacitor
shields to INPUT connector terminals; 5 leads to SW110C
wafer 1 and 1 lead to wafer 3; 2 leads to the DISPLAY
switch. Reconnect 2 leads from attenuator housing to square ­
pin connectors on the Input Amplifier Board.
Tighten down the Output Amplifier Board.
leads to 4 square-pin connectors on top of the board and
2 on the bottom.
previously straddled the rear of the switch assembly.
tach the cable clamp to the rear of the attenuator housing.
Fig. 4-10. Attenuator Section — switch side.
Replace and tighten
Reconnect the 2 shielded leads which
Reconnect
At ­