Tektronix 7834

VERTICAL INTERFACE
The Vertical Interface circuit selects the vertical deflection
signal from the output of the LEFT and/or RIGHT VERT
plug-in compartment(s) for display on the crt . Figure 3-25
shows a detailed block diagram of the Vertical Interface
circuit . A schematic of the Vertical Interface circuit is
shown on diagram 7, at the rear of this manual .
Left and Right Vertical Channel
The operation of the Left and Right Vertical Channel stages
are identical . Therefore, only a discussion of the Left Verti-
cal Channel stage is given .
The Left Vertical Channel stage operates as a switched amp-
lifier . The vertical deflection signal from the left vertical
plug-in unit is either terminated within the stage or coupled
through to the Vertical Amplifier (diagram 14) as deter-
mined by the VERTICAL MODE switch . This stage is made
up primarily
of integrated circuit U4625 .
The input
pins 13
and 16 provide a differential input for the signal from the
left vertical plug-in unit
.
The output signal
at
pins
5
and
8 is
a differential signal, which is
connected to J4688 and
J4689 . Resistors R4625 and R4627 provide termination for
FROM
the left vertical signal
when pin
3 is
LO and pin 10 is HI ; in
this condition the vertical signal is
now allowed
to pass
through the stage to the Vertical Amplifier circuit . Resistors
R4610 and R4611 are selected in conjunction with C4610
and C4611 for optimum bandwidth of the stage .
Vertical Channel Selector
The Vertical Channel Selector controls the Left and Right
Vertical Channel stages . The control signals are applied to
U4625 and U4685 through pins 3 and 10 of both stages .
When
the VERTICAL
MODE
switch is set to
LEFT, the
Vertical Mode Command signal is LO
.
This level allows
the
signal from the left vertical unit to pass to
the
output
while
the signal from the right vertical unit is blocked . In the
RIGHT position of the VERTICAL MODE switch, the
Vertical Mode Command signal is H I . Now, the signal from
the right vertical unit is connected to the output, while
the signal from the left vertical unit is blocked .
When the VERTICAL MODE switch is set to either ALT,
or CHOP, the Vertical Mode Command signal switches be-
tween the
LO and HI
levels
at
a rate determined
by
either
the
Chop Counter or Vertical Binary stages (see Logic
Circuit description) . This action allows the signal from the
VERTICAL
CHANNEL
SELECTOR
Q4633, Q4652
U4641
A, B, C, D
Figure 3-25 . Detailed block diagram of the Vertical Interface circuit .
Theory of Operation-7834
SIGNAL
TO
VERTICAL
AMPLIFIER
1988-50
3- 33