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Nein
Section IV
. Paragraphs 4-90 to 4-95
4-90. At the end of the 100 millisecond initial erasing
period, AlQ11 again starts conducting.
The result-
ing 4.7v negative
step at the collector
of A6Q11
is
differentiated by A6R26/A6C5 and applied to the base
of A6Q7,
turning it off.
A6Q7
will be nonconducting
for approximately
200 milliseconds,
while A6QT
is
off.
The
current
flow through A6R25,
A6R39,
and
A6Q14
causes
the CRT
write gun to remain blanked.
Also, the current flow through A6R24 into the base of
A6Q6 drives it into conduction,
effectively grounding
the base
of A6Q4.
With A6Q4 in an off condition for
the 200 millisecond
period,
the CRT
storage
mesh
rises to about +13.3v when operating in the WRITE
mode,
and to about +7. 5v in the MAX WRITE
mode.
4-91. Whenthe 200 millisecond interval is terminated,
A6Q7 again conducts and turns off A6Q6.
This allows
currenttoflowthrough A6R13, A6CR8 and the base of
A6Q4, turning it on,
and reducing the storage mesh
to the +3. 3v level.
Variable-width erase pulses are
again applied to the storage mesh at the 1 kHz rate.
4-92. Itis desirable to provide for inhibiting the CRT
WRITE functionfor a short intervalafter erasing.
The
Model 181A/AR
discharging time constant of A1C6/A1R10 through A1Q1
accomplishes this, and keeps the write gun turned off
momentarily.
4-93. STORAGE
PROTECTION.
Itispossible to ma-
nipulate the operating mode
selector
switch so that
. multiple functions or nofunctionatallmay be selected.
- This switch is interconnectedtoprovide
several oper-
ationalfeatures which protect the stored display from
inadvertent erasure of overwriting.
For instance,
if
no function is selected, the CRT write gun is blanked
and the PERSISTENCE
control is inoperative.
4-94, The
write
gun blanking is provided by current
flow through A6R22 and A6R40 into the base of A6Q14,
thus causing the Gate Amplifier toturn off the write gun.
4-95. The disabling of the PERSISTENCE control is
obtained by utilizing the current flowing through A6R22
and A6R23 into the base of A6Q4.
This holds A6Q4 in
conduction and keeps the storage meshat +3. 3v. .Cur-
rent flowing intothe base of A6Q4 prevents the variable
amplitude
1 kHz pulse from turning off A6Q4.
Table 5-1.
Required Test Equipment
Test Oscilloscope
Recommended Type
Test Equipment Model
Required Characteristics
Voltmeter
hp Model 738AR
|
1, 2, 10v pk-pk +0. 2%
|
Calibrator
or 6920B
i
hp Model 180A/AR
w/1801A & 1820A
Sensitivity 1v/div
Sweep Speed lu sec
Risetime
3u sec
Sweep output
10:1 Divider Probe
hp Model 10001A
i300
l
Constant Amplitude
Tektronix Type 190B
50 kHz-50 MHz at
i
Signal Generator
10v pk-pk
100:1 Divider Probe
Square Wave Generator
Current Source
Oscillator
Digital
hp Model 3440A
Voltmeter
w/ 34444
hp Model 211A/B
£100vde x0. 5%
2.5 ma € 206
|
hp Model 11044A
300vdc
200 kHz 1v pk-pk
;
Risetime 30 u sec
a
RM
E
2.5
ma +, 30
hp Model 200CD
10 kHz 10v pk-pk
i
02612-2
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