Tektronix 371B, Service Manual

Page: 70 / 292

Theory of Operation
3-10
371B Service Manual
This circuitry is located on the A14 Lower Key & FDD board. The circuit
consists of the bus buffer circuit, the address decoder circuit, the FDD controller
circuit and the FDD bus driver circuit. The function of this circuit is to commu-
nicate with the FDD unit.
This circuitry operates as the power supply for the collector supply circuit in
high-current mode.
This circuitry consists of a high-current pulse generator circuit, high-current
pulse filter circuit, high-current pulse driver circuit, power MOS FETs circuit
and high-current output circuit.
The CRT output amplifier is located on the A18 Output board, and consists of
the horizontal output amplifier, the vertical output amplifier, and the Z-axis
amplifier. The horizontal and vertical output amplifiers convert current signals
from the preamplifier of the A5 Display Control board into deflection plate
driving voltages for the CRT. The Z-axis amplifier converts the current signal
from the unblanking logic of the A5 Display Control board into the driving
voltage for the grid bias and DC restorer circuit of the A20 H.V. Regulator board.
The CRT HV power supply is located on the A20 H.V. Regulator board. This
circuit consists of the high-voltage generator circuit, the high voltage regulator
circuit, the grid bias and DC restorer circuit, the focus amplifier and DC restorer
circuit, the anode multiplier circuit, the rectifier filter circuit, and the CRT
circuit. The CRT HV power supply circuitry provides the various high voltage
operating potentials required by the CRT, and displays the 371B data.
The GPIB and printer interface circuitry is located on the A22 Interface board.
The circuit consists of the bus buffer circuit, the interrupt driver circuit, the
address decoder circuit, the GPIB address switch circuit, the GPIB controller
circuit, the GPIB bus driver circuit, the printer controller circuit and the printer
bus driver circuit. The function of this circuitry is to transfer data to the printer
and to communicate with other instruments via the bidirectional general purpose
interface bus (GPIB). These functions are under control of the microprocessor
and the communication handling software, which are located on the A2 CPU
board.
This circuitry is located on the A25 Main Power Supply board and the A27
Primary board. This circuitry consists of the primary circuit, the main power
supply circuit and the interrupt generator circuit. These circuits supply low
voltage power for the 371B and generate interrupt signals.
FDD Interface
HighĆCurrent Power
Supply
HighĆCurrent Amplifier
CRT Output Amplifier
CRT HV Power Supply
GPIB & Printer Interface
Power Supply