Tektronix 7613 User Manual

Circuit Description —7613/R7613 Service
Display Limited
Current from
Vertical Amplifier
+
CR531
Horizontal
signal from
horizontal
plug-in
compartment ___».
Horizontai
Channel
Switch
CR532
Horizontal
Readout
Signal
Display
Right Output Horizontal deflection
Amplifier signal to right
0539, Q551 deflection plate
Q558, 0560
Left Output Horizontal deflection
Amplifier signal to left
| 0553, 0547 deflection plate
0578, Q580
of CRT
of CRT
Limit Command
from BEAM
FINDER switch
Fig. 3-19. Horizontal Amplifier detailed block diagram.
Display Limit Command is connected to the —15 supply
through the BEAM FINDER switch. When the BEAM
FINDER switch is actuated, the —15 volt is interrupted to
limit the current to U510. At the same time, current is
added through CR531 and CR532 from the display limited
current line. This added current maintains about the same
DC currents through the output circuit in both positions of
the BEAM FINDER switch. The signal at the output is
connected to the right and left amplifier inputs. Resistor
R525 adjusts the amplifier for center screen deflection in
the absence of an input signal to U510.
Output Amplifier
Transistors 0539, 0551, 0558, and O560 function as a
current driven feedback amplifier. The input current is
converted to a voltage output signal to drive the right
horizontal CRT deflection plate. R558 establishes the
quiescent current level for series connected transistors
0558 and O560.
The CRT deflection plates present a capacitive load to
the amplifier, which requires additional current during fast
transients. Extra current for positive excursions is provided
3-22
by 0551 via R555, C555, and O558; for negative excur-
sions, by 0560 via R563.
Resistor R556 reduces the power dissipation in Q558,
Resistors R566, R567, and R569 provide DC feedback and
establish low frequency gain. Capacitors C566 and C588
(C568 for lower serial numbers) are adjusted for correct
gain at fastest sweep rates {in later serial numbered
instruments, C588 replaces C568 and a differently located
C588, a thermal compensation network C584-R584 is
added).
Basic operation of the Left Output Amplifier stage is the
same as described for the Right Output Amplifier. C586
and C588 set the gain for the fastest sweep rates (C588 is
relocated for later serial numbers and affects both Right
and Left Output Amplifiers). The output signal at the
collectors of 0578-0580 connects to the left deflection
plate of the CRT through R585.
The series circuit CR549 and R549 stabilize the output
amplifier during fast retrace intervals. R535 is adjusted to
balance the negative excursions of the right and left sides of
the amplifier when the time base plug-in is used in X10
Magnified mode.
7613

Tektronix 7613 Specifications

General

Brand	Tektronix
Model	7613
Category	Test Equipment
Language	English