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Circuit Description—485/R485 Service
coupling path for AC changes to the input of U1624. The
output correction is AC coupled through C l612 directly to
the cathode. CR1618, CR1621, CR1626, and CR1627
provide short-circuit protection.
Grid DC Restorer. The purpose of the DC restorer
circuit is to elevate the output of the Z-Axis amplifier to a
potential more negative than the cathode, thereby allowing
the grid to control the beam current of the CRT. The
circuits are short-circuit protected by R1685, DS1684,and
DS1685; R1668, DS1668, and DS1669.
The DC Restorer is current driven from the square wave
at the high voltage winding through R1603, R1604, R1605,
and R1606. When T1960 goes positive, CR1660 conducts
at the grid bias voltage potential. This clamping action
establishes the positive swing of the DC Restorer drive. On
the negative swing of T1960, CR1663 conducts at the
voltage established by the Z-Axis output. This clamping
action establishes the negative swing of the DC Restorer
drive. The AC swing of the DC Restorer drive is coupled
from the low voltage section to the high voltage section by
C l663. On the positive swing of the DC Restorer drive, the
high voltage end of C l663 is clamped to the cathode
voltage by CR1666. During the negative swing of the DC
Restorer drive, CR1664 charges Cl 664 to a voltage more
negative than the cathode by an amount equal to the
difference between the grid bias setting and the voltage at
the output of the Z-Axis amplifier. Fast AC-coupling
between the Z-Axis and the CRT grid is provided by
C1684. A slower AC path is by way of R1684 and C1664.
Focus DC Restorer. The operation of the Focus DC
Restorer circuit is similar to the operation of the Grid DC
Restorer. The AC swing of the DC Restorer drive is coupled
from the low voltage circuit to the high voltage circuit by
C1651. The positive swing w ill be established when
CR1656 clamps at the Focus DC Restorer level voltage.
This voltage is approximately 173 V. The negative swing is
established when CR1652 clamps at the output voltage of
the Auto-Focus amplifier. During the positive swing of the
Focus DC Restorer drive, the high voltage end of C l651 is
clamped to the focus pot voltage by CR1646. During the
negative swing of the Focus DC Restorer drive, CR1651
charges C1652 and thereby establishes the proper level at
BEAM CURRENT
Fig. 3-7. CRT circuit block diagram.
REV. B, AUG. 1975
3-13
Содержание 485
Страница 3: ...485 R485 rviice T h 5 0 Oscil oscope ...
Страница 32: ...Maintenance 485 R 485 Service 4 4 Fig 4 1 Electrode configuration for semiconductors in this instrument ...
Страница 74: ...Rackmounting 485 R485 Service 6 6 ...
Страница 128: ...485 R485 Service MAR 1979 5 m V B A L ADJ ...
Страница 134: ... See Parts List for Fig 8 5 A 7 Partial Vertical am plifier board serial num ber ranges R E V D S E P T 1974 ...
Страница 137: ...Fig 8 6 A 7 Partial Vertical am plifier board See Pgrts Ljsf for serial number ranges f R E V B S E P T 1974 ...
Страница 145: ...Fig 8 9 A l l Partial Horizontal amplifier board REV E AUG 1975 See Parts List for serial number ranges ...
Страница 152: ... 0 iT s i ...
Страница 153: ...W H I T C X Y I6 J ROM Q S X J I 4 8 5 O S C U L O C O P E II93 4S REV D A J l 57fe HORIZONTAL A M P L IF IE R U ...
Страница 159: ...OSCILLOSCOPE 3 0 0 0 V TE ST P O IN T M AR K E D 2 9 5 0 V IN SOME INSTRUMENTS R EV e M AR 19 70 7 93 52 MRS ...
Страница 164: ...2S2 n eKn s e s 5 4 85 Os c illo sc o p e REV F A U S 1 9 7 7 I 1 9 3 5B POWER SUPPLY 773 ...
Страница 168: ... O I P 4 c N ifl 0 t 4 8 5 O S C I L L O S C O P E 2 d2 2 m u J tP Z O u u r 7 OJO d U O Hi 0u o o J ...
Страница 178: ......
Страница 179: ...485 R485 OSCILLOSCOPE REV D MAR 1977 ...
Страница 184: ...REV C MAR 1976 485 R485 OSCILLOSCOPE ...
Страница 197: ......