A1A2 Z Axis Amplifier, Circuit Description
(Serial Number Prefixes: 2403A-3001A)
A1A2 Z Axis Amplifier receives from A3A2 Intensity Control two signals for control of the
CRT: a 0 V - 2 V Z signal proportional to the CRT writing rate, and a blanking signal
LBLANK.
Amplifier
(A)
The Z signal, after attenuation by the front-panel INTENSITY potentiometer A1R1, drives
the input stage Q9-Q10. This amplifier supplies a differential current output to the Focus
Gate Amplifier and, through a Blanking Switch, to the Control Gate Amplifier.
Blanking Switch ®
Control Gate Amplifier ©
The input to the Control Gate amplifier is a virtual-ground, current-summing junction. Its
output voltage is given by:
Where I
Q7
is the current in Q7, which is determined by the Z-axis input when LBLANK is
high. When LBLANK is low, Q7 is off, and the output of the Control Gate amplifier drops to
a few volts, blanking the CRT.
Focus Gate Amplifier ©
The Focus Gate Amplifier supplies a correction voltage to the FOCUS grid of the CRT
to compensate for defocusing effects with varying intensity levels. The magnitude of this
correction voltage is set by FOCUS GAIN potentiometer R30 and the front-panel FOCUS
screwdriver adjustment A1R2. The output stage is identical to that of the Control Gate
Amplifier except for the pulse response adjustments (HF GAIN potentiometer R22 and HF
TRIM capacitor C10 in the Control Gate Amplifier). These components are fixed in the Focus
Gate Amplifier.
CRT Adjustments (§)
The CRT Adjustments set the bias voltage for the various CRT functions. Each adjustment
name is indicated on the schematic.
2 A1A2
To Next Page
Loading...
