Tektronix 7834 User Manual

Theory of Operation-7834
(DISPLAY B)
3- 1 2
ALT MODE (HORIZ)---
A GATE -
X-COMPENSATION INHIBIT
(A HORIZONTAL)
X-COMPENSATION
INHIBIT
(B
HORIZONTAL)-°~
DELAYMODE CONTROL ---
B HOLDOFF-
MAIN
FRAME CHANNEL SWITCH SIGNAL
(DISPLAY B)
ALT MODE (HORIZ)-{
X-COMPENSATION INHIBIT (A
HORIZONTAL)
X-COMPENSATION INHIBIT (B HORIZONTAL)-
DELAY MODE CONTROL---
MAIN FRAME CHANNEL
SWITCH
SIGNAL-
X-COMPENSATION
INHIBIT
(A
HORIZONTAL)-
X-COMPENSATION INHIBIT (B HORIZONTAL)-
A HOLDOFF-
B MODE ----~
B HOLDOFF----~
A MODE -- °
DELAYMODE CONTROL --- 1
As
shown by Figure 3-6B, the output of this stage is H I only
under one set of input conditions to V4428 . This -set of
conditions disables the B sweep while the A sweep is being
displayed in the ALT, HORIZONTAL MODE switch posi-
tion, if both time-base units are in a sweep mode and non-
delayed sweep is used . For any other
combination of input
conditions, the
B Sweep Lockout level is determined by the
Delay
Gate
(from A time-base unit) and the Storage Lock-
out signal (from Storage Control, diagram 18) .
Figure 3-6A shows Delay Gate and Storage Lockout con-
nections to the output of the B Sweep Lockout stage
through a phantom-OR gate . (A phantom-OR gate performs
the OR logic function merely by interconnection of two or
more signal lines
.)
ALTERNATE PULSE STAGE . The third function
per-
formed by the Horizontal Logic stage is to produce an
Alternate Pulse signal for use by the Horizontal and Vertical
Binary stages, and the Storage Sweep Gate circuit on the
mode switch circuit board .
(1) A (Only) Mode
A LOCKOUT
--- ALT OUT
Figure 3-4 . Breakdown of separatg :stages'within Horizontal Logic IC (U4428) :
showing inputs and outputs for each stage .
(1195-4) 1988-29
The Alternate Pulse is
produced at the end of either sweep,
depending
upon the operating conditions as shown
in
Figure 3-7B
. The holdoff gate produced at the end of the
sweep by the
respective time-base unit is differentiated by
either
C4420 or C4423 to provide a positive-going
pulse to
pin 6 or 9 of U4428 .
In Figure 3-7A,
note the resistors shown connected to pins
6 and 9 . These resistors,
which are internal to the IC, hold
the
levels
at
pin 6 and 9 LO unless a HI level is applied to
the
corresponding input . Since the holdoff gate is
capacitively-coupled to pins 6 and 9, these inputs are at the
LO level except when a differentiated A or B Holdoff gate
is received .
The following discussions describe the operation of
the
Alternate Pulse stage in relation to the various
combinations
of input conditions shown in Figure 3-7B
.
An Alternate Pulse is produced at the end of each
A
sweep when the HORIZONTAL
MODE
switch
is set to
the A position .

Tektronix 7834 Specifications

General

Brand	Tektronix
Model	7834
Category	Test Equipment
Language	English