Tektronix 7623, Instruction Manual

Page: 63 / 266

Circuit Description— 7623/R7623 Service
diagram of the Vertical Interface circuit. A schematic of
this circuit is shown on diagram 3 at the rear of this
manual.
Vertical Channel Switch
The Vertical Channel Switch stage determines which
input signal provides the vertical signal to the Delay-Line
Driver stage as controlled by the Mainframe Vertical Mode
Command from the Logic circuit. Resistors R200-R202 and
R204-R206 establish the input resistance of this stage and
provide a load for the left and right vertical units. Resistors
R209-R211-R212 and R216-R218-R219 establish the oper­
ating levels for this stage. R209-R212 and R216-R219 set
the current gain for each channel. C208-R208 and
C215-R215 provide frequency compensation.
Fig. 3-15. Input/output table for T rigger Channel Switch stage.
VERTICAL INTERFACE
The Vertical Interface circuit selects the vertical deflec­
tion signal from the output of the left vertical and/or the
right vertical plug-in unit. Fig. 3-16 shows a detailed block
This stage is made up primarily of integrated circuit
U214, which is the same type as used for the Trigger
Channel Switch. An input/output table for U214 is shown
in Fig. 3-17. U214 provides a high impedance differential
input for the signal from the left vertical unit at pins 2 and
15, and the signal from the right vertical unit at pins 7 and
10. The output signal at pins 12 and 13 is a differential
signal which is connected to the Delay-Line Driver stage
through
R222-R224. The sum of the DC output currents at
3-19