Maintenance—Type 324
CRT pin location and orientation in the oscilloscope is
shown in Fig. 4-12.
Do not strike the flanges (near the face of the CRT)
against the shield when inserting the CRT in the shield.
Fig. 4-12. Sketch of CRT base as viewed from rear when installed
in oscilloscope.
When putting the CRT and shield in place, install the
C RT shield inside the flanges on the right and left sides of
the front panel CRT opening. The top of the shield must fit
below the double flange at the top of the front casting.
(The oscilloscope case fits between the flanges.)
Replace the shield-bracket nut and bolt before the nylon
screw, but do not tighten them until the plastic spacer and
the nylon screw have been installed and tightened. The
flanged side of the plastic spacer should face the front of
the assembly, and the nylon screw must fit in the depres
sion at the center of the spacer.) Use moderate torque to
fasten the nylon screw, and then tighten the shield-bracket
nut and bolt.
It is recommended that the Type 324 be recalibrated
whenever a replacement CRT is installed.
Vertical Circuit Board
Most of the circuit components can be replaced without
removing the circuit board. However, if access to the under
side of the board is necessary or the board needs to be
removed from the instrument, proceed as follows:
Before unsoldering the wires connected to the vertical
circuit board, record their color codes to facilitate installa
tion.
The four transistors mounted in heat sinks on the instru
ment rear panel can be slipped out of the heat sinks. It is
not necessary to unsolder the transistor leads from the cir
cuit board.
Remove the three screws that hold the circuit board to
the chassis and lift the board away from the chassis.
Horizontal Circuit Board
Most of the circuit components on the horizontal circuit
board can also be replaced w ithout removing the circuit
board. However, removal of the board can be easily
accomplished by proceeding as follows:
Before unsoldering the wires connected to the horizontal
circuit board, record their color codes to facilitate re-
-installation.
Remove the three screws that hold the circuit board to
the chassis and lift the board away from the chassis.
Position Bracket
Remove both POSITION knobs. Remove one securing
nut and lock washer from each end of the POSITION
bracket. Move the rear of the bracket away from the
chassis, as far as the cables will allow. Then move the
bracket back and out, hinging it on the cables at the rear of
the bracket.
TRIGG ER Control Assembly
Remove the T R IG G E R knob; then remove the nut and
flat washer from the exposed bushing. L ift the back of the
assembly away from the chassis and pull it back until the
shaft clears the front panel. Note that the internal lock
washer is in place between the T R IG G E R assembly and the
front panel during re-installation.
INPUT and Trig/Horiz Coupling Switches
These can be removed after two nuts have been removed
from the back, and the pressure-fit knob has been pulled
from the lever arm. To avoid damage to switch contacts,
unsolder the coupling capacitor (C20) before removing the
IN PU T Coupling switch.
POWER Switch
The face plate must be removed from the oscilloscope to
expose the two screws holding this switch in place. The
4-14
