A1A3
A1A3 High Voltage Regulator (85662-60059), Circuit Description
(Serial Number Prefixes: 2403A-3001A)
Warning The CRT filament potential is connected to the -4000 V dc cathode potential,
which is dangerous to life.
6
The post-accelerator potential of approximately +18 kV is supplied by High Voltage
Multiplier
A1A11.
Refer to block diagram.
High-Voltage Transformer
(A)
High-Voltage Rectifier and
Filter (§)
The cathode of CRT A1V1 operates at -4000 V dc. This voltage is generated by rectifying
an ac signal (approximately 30 kHz) on the secondary of High-Voltage Transformer Tl. The
primary side of Tl is an oscillator circuit located in A1A6 ±15 V Regulator. The rectifier
circuit consists of CR1 and filter components Cl, R3, and C3. The CRT filament voltage of
4.45 V rms is generated by another secondary winding of Tl and is held at -4000 V dc by
Rl.
The cathode voltage is stabilized by a feedback control circuit consisting of R4, C4, and the
amplifier circuit in A1A6 ±15 V Regulator in conjunction with a primary feedback winding
on Tl. Refer to the circuit description of
A1A6.
The cathode voltage is set by HV ADJ
potentiometer A1A6R32 in the Oscillator Level Control circuit of A1A6.
Control Grid Level Shift (c)
The control grid voltage is provided by generating a bias voltage with respect to the cathode
voltage. This bias voltage is generated by a capacitively coupled, clipped sine-wave signal
at the junction of C2 and C5. The sine wave is derived from the Tl secondary through R2.
The upper clipping level is set by INTENSITY LIMIT adjustment A1A2R35 in A1A2 Z Axis
Amplifier. The lower clipping level is set by the output of the Control Gate Amplifier in
A1A2.
The clipped sine-wave signal is coupled to the control grid circuit through C5, where
it is rectified by CR3 and CR4 to generate a dc bias voltage across R7. C6, R10, and C7
constitute a filter to remove ripple from the bias voltage. C7 also allows fast pulse signals to
be coupled directly to the control grid, to maintain response times of 30 ns or less.
A1A3 1
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