Circuit Description—455/A2/B2
Horizontal Preamplifier 1C
The Horizontal Preamplifier circuit is contained within a
single 1C, U2900.
The following is a brief description of the function associat
ed with each pin of U2900.
Pin 1. Magnifier registration. This pin is used in con
junction with pin 8 to provide registration between the
normal and magnified sweeps.
Pin 2. Sweep. This pin provides the negative-going
sweep output to the Horizontal Output Amplifier. This
output represents the inputs to pin 9 or 10, except in the
X-V mode when pin 12 is HI, and it represents the input
to pin 11.
Pin 3. Gain. This pin, in conjunction with pin 6, is con
nected to the gain setting circuitry. The X I0 Magnifier
switch is connected to this pin.
Pin 4. —5 volt supply.
Pin 5. Current source. Sets internal current levels.
Pin 6. Gain. See pin 3.
Pin 7. + Sweep. This pin provides the positive-going
sweep output to the Horizontal Output Amplifier.
Pin 8. Magnifier registration. See pin 1.
Pin 9. B Sweep In. Input connection for the B sweep
signal.
Pin 10. A Sweep In. Input connection for the A sweep
signal.
Pin 11. X Signal. Input connection for the X signal
from CH 1 when the A TIME/DIV switch is in the X-Y
position.
Pin 12. X-Y Mode. When this pin is LO (normal sweep
mode), the outputs at pins 2 and 7 represent the inputs
to pin 9 or pin 10.
Pin 13. Frequency compensation. Connects to frequen
cy compensating capacitor.
Fig. 4-9. Sweep-circuit waveform
relationships.
9
REV. A, OCT 1975
Pin 14. Horizontal position. Connects to the horizontal
POSITION control.
To Next Page
General
