Circuit Description—475
SWEEP G ENERATORS
General
The Sweep Generators produce the sawtooth voltages
that are amplified by the Horizontal Amplifier to provide
horizontal deflection on the C R T. These sawtooth voltages
are produced on command (trigger pulses) from the Trigger
Generator circuits. The Sweep Generator circuits also
produce gate waveforms that are used by the Z Axis Logic
circuit to unblank the C RT during sweep time, and by the
Sweep Logic circuit to terminate sweep generation. There
are three Sweep Generator circuits in the instrument.
Operation of all three is very similar; therefore only the
operation of the Delaying Sweep Generator and the
differences in operation of the three generators is discussed.
Fig. 3-6 shows a detailed block diagram of the Sweep
Generators. A schematic of the Sweep Generators is shown
on Diagram 8 at the rear of this manual.
Delaying Sweep Generator
Basically the Delaying Sweep Generator is composed of
Q904, Q920, Q 922# and Q914. This generator only runs in
the A IN T E N , M IX , and B D L Y 'D positions of the H O R IZ
DISPLAY switch and generates the A portion of the
display. The sweep rate is selected by the A T IM E /D IV
switch.
Main Gate Amplifier
Q902 is the Main Gate Am plifier stage. The negative
going Main Gate waveform from the Sweep Logic circuit is
applied to the base of Q902. The amplified and inverted
waveform at the collector of Q902 is applied to the
Delaying Sweep Generator (through C R 903), or to both of
the Non-Delaying Sweep Generators (through Q 992). This
initiates sweep generation.
Sweep Disconnect Amplifier
Q904 is the Sweep Disconnect Amplifier. The biasing on
the base of this stage determines whether the Delaying
Sweep Generator will run. In the A position of the H O R IZ
D ISPLAY switch, the anode of CR907 is connected to +5
volts through R908 and the H O R IZ DISPLAY switch. This
biases the base of Q904 far enough positive that the
positive-going gates on the emitter cannot turn off Q904.
Q904 therefore conducts all of the timing current through
timing resistor Rt , keeping timing capacitance Ct dis
charged. When the H O R IZ D ISPLAY switch is in any
position other than A , the anode of CR907 is connected to
—8 volts. CR907 is now reverse-biased, which lets the base
of Q904 be biased at a level that will allow the positive
going gates on the emitter of Q904 to interrupt the current
flow through Q 904. When Q 904 turns off, the timing
current starts to charge timing capacitance Ct-
DELAY PIGKOFF
3-12
®
Summary of Contents for 475
Page 6: ...475 475 Oscilloscope ...
Page 20: ......
Page 46: ......
Page 151: ...A B C D E F G Fig 7 4 P 0 A4 Vertical Mode Switch circuit board ...
Page 152: ...n m m m 1 t siumm c ii im ...
Page 154: ...Diagrams 475 A B C D E F G ...
Page 155: ...GRID LOCATOR Fig 7 8 P O A3 Vertical Preamp circuit board ...
Page 157: ...Diagrams 475 ...
Page 158: ...GRID LOCATOR 2 3 4 5 6 7 8 9 1 10 11 1 12 Fig 7 10 P 0 A3 Vertical Preamp circuit board ...
Page 160: ...Diagrams 475 GRID LOCATOR Fig 7 11 A5 Vertical Output circuit board ...
Page 163: ...Diagrams 475 GRID LOCATOR Fig 7 12 P O A8 Trigger Generator And Sweep Logic circuit board ...
Page 167: ... 415 OSCILLOSCOPE B T R IG G E R G E N E R A T O R g B TR IG G E R GEN ER A TO R ...
Page 168: ...Diagrams 475 GRID LOCATOR ...
Page 172: ...SWEEP G E N ER A TO R S ...
Page 175: ...TIM IN G HORIZONTAL DISPLAY SWITCHING ...
Page 177: ...A 011 HORIZONTAL AMPLIFIER 8 l j k J Ll J Ol Z o N C O X U 1 C L O o v O o _J V v P O in r ...
Page 179: ... 476 OSCILLOSCOPE ...
Page 180: ...POWER SUPPLY ...
Page 182: ...CRT CIRCUIT ...
Page 185: ...C A L IB R A T O R A N D F A N C I R C U I T 4 C A LIB R A TO R FAN MOTOR C IR C U IT ...
Page 189: ......
Page 190: ...4 T 475 OSCILLOSCOPE FIG 1 FRO NT PANEL ...
Page 191: ...475 OSCILLOSCOPE FIG 2 MAIN FRAME ...
Page 199: ......
Page 200: ...FIG 3 RIGHT SIDE l 475 OSCILLOSCOPE ...
Page 201: ...V S X O t l B O T T OVJ 8 8 ...
Page 209: ......
Page 210: ...5 ...
Page 211: ...4 4 75 O S C ILLO S C O P E FIG 5 CAB IN ET ...
Page 215: ......
Page 237: ......
Page 241: ... 1 I R I II9A po S IT I o n f i n e I R l 130 PAGE 4 OF 5 R 1234 Ml 9 91 9 473 ...