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Theory of Operation— 2236 Service
functions as described above. When the output of U660F
goes HI, U670A is no longer held reset and the first B trigger
signal from the collector of Q630 will clock through the HI on
the D input. The Q output of U670A will then go LO and a B
Sweep will be initiated.
Alternate Display Switching Logic
The Alternate Display Switching Logic circuitry controls
both the Horizontal Amplifier sweep switching and the B Z-
Axis Logic switching.
HORIZONTAL MODE switch S648 selects the input logic
levels that are applied to the circuitry. In the^ Horizontal
Mode, the S input of U670B is LO and the R input is HI.
This holds U670B set and allows only the A Sweep to be
passed to the Horizontal Amplifier. In the B Horizontal
mode, the set input of U670B is HI and the reset input is LO
to hold U670B reset and allow only the B Sweep to reach
the Horizontal Amplifier.
With S648 set to ALT, and for all settings of the VERTI
CAL MODE switches except BOTH-ALT, the Valt signal ap
plied to U660E and the S and R inputs of U670B are all HI.
The LO output of U660E causes the output of U680B to be
HI, and whenever the Alt Sync signal applied to pin 1 goes
LO, the gate output will change from LO to HI and clock
U670B. The outputs of U670B will therefore toggle with
each Alt Sync signal transition to alternately enable the A
and B Sweeps to reach the Horizontal Amplifier. Whenever
the B Sweep is selected for the Horizontal Amplifier, the Q
output of U670B will be HI. This HI is applied to U665C pin
9, and since pin 10 is also HI, the Sep signal from U665C
will be LO to enable the A/B Sweep Separation circuitry.
When the CH 1-BOTH-CH 2 VERTICAL MODE switch is
set to BOTH, the ADD-ALT-CHOP switch becomes func
tional. In the ALT VERTICAL MODE position, the Valt signal
is LO, the Halt signal is HI, and the CH 1 Selected signal is a
TTL square wave that switches states at the end of the A
Sweep. Input pin 4 of U680B will be HI and the gate output
will be the inverse of the CH 1 Selected signal. This output
signal is NANDed with the Alt Sync signal by U680A to
clock U670B. Whenever the Alt Sync signal goes LO at the
end of a sweep and the Ch 1 Selected signal switches from
LO to HI, U670B will be clocked. Since only positive transi
tions on the clock input will cause the flip-flop to change
output states, two A Sweeps are required to cause the flip-
flop output levels to switch. With this switching arrange
ment, the crt will first display the two A Intensified Sweeps
and then the two Alternate B Sweeps.
B Z-Axis Logic
The B Z-Axis Logic circuitry switches signal current lev
els to drive the Z-Axis Amplifier for both the B and the A
Intensified Sweep displays. The current supplied is summed
with the other signal inputs on the Z-Drive line.
When the HORIZONTAL MODE switch is in the ALT po-
sition, pin 5 of U665B is HI. The outputs of U670B and the
B Gate signal from the output of U665D together with the
INTENSITY controls determine the intensity of the A and B
Sweeps. The B Gate signal is applied through R679 to the
Digital Section of the Delay/Delta Time Controller in the
CTM circuitry.
When the A Sweep is displayed, the Q output of U670B
is HI and the Q output is LO. These output levels will bias on
Q680 and bias off Q685. The emitter voltage of Q680 will
reverse bias CR817 to prevent Z-Axis drive current from
flowing through the diode. With Q685 off, additional Z-Axis
drive current to intensify the A Sweep will be supplied when
ever CR685 is biased off. Since input pin 5 of U665B is HI,
the gate output and therefore the conduction state of
CR685 is determined by the Ctrintens signal from the Inten
sified Zone Controller in the CTM circuitry. Whenever the B
Sweep is running, the output of U665B will be LO and
CR685 will be biased off whenever Ctrintens is HI. If the B
Sweep is not running, the output of U665B will be HI and
CR685 will be biased on. This will bias off CR816 and the A
Sweep will not be intensified.
If the outputs of U670B are set to display the B Sweep
(Q LO and Q HI), Q680 will be biased off and Q685 will be
biased on. The emitter voltage of Q685 will reverse bias
CR816 to prevent Z-Axis drive current from flowing through
the diode. With Q680 off, the B Sweep will be displayed if
CR680 is reverse biased. Whenever the B Sweep is running,
the output of U665D is LO. Diode CR680 will then be re
verse biased and Z-Axis drive current will flow through
CR817. If the B Sweep is not running, the output of U665D
is HI, forward biasing CR680 and therefore reverse biasing
CR817. No Z-Axis drive current can then flow through
CR817.
HORIZONTAL
The Horizontal Amplifier circuit, shown on Diagram 6,
provides the output signals that drive the horizontal crt de
flection plates. Signals applied to the Horizontal Preamplifier
can come from either the A or the B Miller Sweep Generator
(for sweep deflection) or from the XY Amplifier (when X-Y
display mode is selected). Sweep switching is under control
of the Alternate Display Switching Logic circuit. See Figure
3-4 for the block diagram of the Horizontal Amplifier.
The Horizontal POSITION control, X I0 Magnifier cir
cuitry, and the horizontal portion of the Beam Find circuitry
are also contained in the Horizontal Amplifier circuit.
Horizontal Preamplifier
The Horizontal Preamplifier selects display modes and
amplifies input signals for application to the Horizontal Out
put Amplifier.
3-14
REV MAR 1985
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 319: ...2236 Service TROUBLESHOOTING GUIDE 4206 99 4204 69A ...
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