Block Diagrain; Vertical Amplifiers; Trigger And Ho'rizont3', Amplifiers - Tektronix 2212 Service Manual

Vertical Amplifiers
Trigger and Horizontal
Amplifiers
2212 Service Manual
Block Diagram
This subsection contains a description of the simplified 2212 blockdiagram
(Figure 3-1).
In the 2212 oscilloscope the following main parts can be distinguished:
Vertical Amplifiers
- Trigger and Horizontal Amplifiers
- Digital Storage
Front panel and System Control
High and Low Voltage Power Supply
Z-axis
The vertical amplifier has two input channels. They consist of a programmable
attenuator, a FET input buffer and a pre-amplifier circuit.
The pre-amplifier contains a digitally controlled gain switching circuit and a
vertical enable input. The overall gain of the pre-amplifier can be controlled
with a de voltage. The output signals of pre-amplifiers of CH1 and CH2 are
differential signal currents, that are summed in the input stage of the delay line
driver. The pre-amplifier provides also a trigger signal and a vertical signal for
the digital storage circuit. Attenuation, gain and mode of the pre-amplifier
circuits are controlled by the system control circuit. Control data is loaded in a
shift register chain and applied to the appropriate inputs of the pre-amplifiers.
The vertical positioning signals and vertical readout data are through the verti-
cal position control circuit applied to the delay line driver. The delay line driver
amplifies the signal to a level sufficient to drive the vertical output amplifier.
The trigger circuit receives input signals from the CH1 and CH2 pre-amplifiers,
from the EXT trigger input and from a line source.
Source selection is performed with digital control signals. The output signal
from the trigger circuit is connected to thesweep logic and sweep generator
circuit.
The sweep logic determines the mode of operation of the sweep generator. The
mode of operation and the sweep speed are controlled by the system processor.
The sweep logic also generates hold off signals to allow the sweep generator and
horizontal amplifier circuits to stabilize after sweep return.
3-3