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Theory of Operation— 2236 Service
GENERAL DESCRIPTION
NOTE
When reading this general circuit description of the
2236 Oscilloscope, refer to the block diagrams (Fig
ures 9-4 through 9-7) located in the “Diagrams" sec
tion of this manual. The numbered diamond symbol in
each major block refers to the appropriate schematic
diagram number.
OSCILLOSCOPE
Signals to be displayed on the crt are applied to either
the CH 1 OR X input connector or the CH 2 OR Y input
connector. These signals may be directly (DC) coupled to
the attenuator circuit or ac (AC) coupled through an input
coupling capacitor. The input signals may also be discon
nected from the oscilloscope circuitry and the input
attenuator grounded by setting the coupling switch to the
GND position.
The output signal from the Attenuator circuit is applied to
the Vertical Preamplifier for further amplification. Addition
ally, the Channel 2 Attenuator can invert the Channel 2 dis
play on the crt. Trigger Pickoff Amplifiers in each channel
supply an internal trigger signal from either or both channels
to the Internal Trigger Amplifier.
Input signals are selected for display by the Channel
Switching circuit under control of the front-panel VERTICAL
MODE switches. The output signal from the Channel
Switching circuit is applied to a Diode Gate circuit to enable
either the vertical or trigger view signal to drive the Delay
Line Driver stage. This stage converts a current input to a
voltage output and provides an impedance match for the
Delay Line. The Delay Line produces approximately 90 ns of
delay in the vertical signal. This allows the Horizontal cir
cuitry time to start the sweep so that the operator can see
the signal that triggered the sweep.
Final amplification of the vertical signal is performed by
the Vertical Output Amplifier. This Amplifier supplies the sig
nal levels necessary for vertical deflection of the electron
beam in the crt. The upper frequency response of the Ampli
fier can be reduced by enabling the Bandwidth Limit cir
cuitry. For locating the position of off-screen displays, the
dynamic range of the Amplifier can be limited with the Beam
Find circuitry. This circuitry also intensifies the trace and
limits horizontal deflection.
The A/B Sweep Separation circuitry supplies a dc-offset
current to the Vertical Output Amplifier which vertically posi
tions the B trace with respect to the A trace when Alt Hori
zontal Mode is selected.
The A Trigger circuitry uses either an Internal Trigger sig
nal, an External Trigger signal, or a Line Trigger signal ob
tained from the ac power line to develop the gate signal for
the A Sweep Generator. The B Trigger circuitry uses only
the Internal Trigger signal to gate the B Sweep Generator. A
P-P Auto Trigger circuit ensures that the range of the A
TRIGGER LEVEL control tracks the peak-to-peak ampli
tude of the trigger signal when either the P-P Auto or TV
Field trigger mode is selected. This allows triggering on
most signals without needing to adjust the A TRIGGER
LEVEL control. In Norm Mode, the A TRIGGER LEVEL con
trol must be adjusted for the correct trigger signal level be
fore a sweep can be generated. When the TRIG VIEW
switch is activated, the signal appearing at the input of the A
Trigger circuit is applied to the Delay Line Driver and dis
played on the crt.
A TV Field sync circuit provides stable triggering on tele
vision vertical-sync pulses. Triggering at the television line
rate is accomplished when either P-P Auto or Norm mode is
selected.
The A Sweep Logic circuit controls sweep generation
and Z-Axis unblanking for the A Sweep display. When the A
TRIGGER Mode switches are set to either P-P AUTO or TV
FIELD and no trigger signal is present, the Auto Baseline
circuit causes the Sweep Logic circuit to produce a sweep
for reference purposes. In the NORM setting, the Auto
Baseline circuit is disabled and sweeps are inhibited until a
trigger event occurs. This is useful for triggering on low-
repetition-rate signals. The SGL SWP setting enables only
one sweep to be generated after being reset. Following the
single sweep, the A Trigger circuit is disabled until the SGL
SWP button is pressed again.
The A Sweep Logic circuit controls the operation of the A
Miller Sweep Generator circuit. The Sweep circuit produces
a linear sweep output with a ramp time that is controlled by
the A SEC/DIV switch. The sweep signal is applied to the
Horizontal Preamplifier for initial amplification and then to
the Horizontal Output Amplifier to drive the crt horizontal
deflection plates.
The Horizontal Preamplifier gain is increased by a factor
of 10 when the X I0 Magnifier is used. Horizontal positioning
of the display is accomplished in the Horizontal Preamplifier
circuit.
3-2
Содержание 2236
Страница 10: ...2236 Service viii The 2236 Oscilloscope ...
Страница 28: ...Specification 2236 Service 1 18 ADD JAN 1985 Figure 1 2 Physical dimensions of the 2236 Oscilloscope ...
Страница 74: ...Theory of Operation 2236 Service 3 30 ...
Страница 75: ...Theory of Operation 2236 Service Figure 3 13 Typical waveforms for the Delta Time function with Valt HI 3 31 ...
Страница 102: ...Performance Check Procedure 2236 Service 4 21 Figure 4 1 Test setup for DMM common mode check ...
Страница 240: ...2236 Service CTM INTERFACE SIGNALS F ig u re 9 4 O s c illo s c o p e b a sic b lo c k diag ram 4294 46 ...
Страница 241: ... VERT DEFL 2236 Service 4 2 0 6 3 5 4 2 0 4 4 7 F ig u re 9 5 O scillo sco p e d e ta ile d b lo c k diag ram ...
Страница 242: ...2236 Service 4204 34 Figure 9 6 CTM basic block diagram ...
Страница 243: ...DMM POWER S U P P LIE S 2236 Service F ig u re 9 7 C T M d e ta ile d b lo c k diag ram ...
Страница 253: ...A10 COUNTER TIMER MULTIMETER BOARD F ig u re 9 8 C irc u it b o a rd lo c a tio n Illu s tra tio n ...
Страница 254: ...S I 0 O I 5 1 S O i 4204 21 C IR C U IT BOARD INTERCONNECTIONS ...
Страница 255: ...2 2 3 6 S e rv ic e A ll c o m p o n e n ts on th e A 2 A tte n u a to r b o a rd are lo c a te d on D ia g r a m ...
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Страница 313: ...2236 Service T O U I 3 0 0 4 8 K T O UI300 II S K 0 2 2 3 6 Z Z O A Z 2 OPTION IA ...
Страница 317: ...A 10 C O U N T E R T IM E R M U L T IM E T E R B O A R D A D J U S T M E N T LO C A T IO N S ...
Страница 319: ...2236 Service TROUBLESHOOTING GUIDE 4206 99 4204 69A ...
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