Circuit Diagrams; Introduction; Block Diagram; Schematic Diagrams - HP 428B Operating And Service Manual

Model 428B

7-1. INTRODUCTION.

7-2. This section contains the circuit diagrams necessary
for the operation and maintenance of the Model 428B
Clip-on DC Milliammeter. Included are a block diagram,
schematics and component location diagrams.

7-3. BLOCK DIAGRAM.

7-4. The block diagram shows the relationship between
the assemblies of the instrument. Signal flow between
assemblies and significant portions of assemblies as well
as major feedback paths are shown. The block diagram
is used to develop an understanding of the basic theory
of operation.
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SECTION VII

CIRCUIT DIAGRAMS

SCHEMATIC NOTES
MEASUREMENT CONDITIONS.
Line voltage:
Range:
Input:
All voltages were measured with a high input impedance
electronic voltmeter. A 10 megohm oscilloscope probe was
used to measure the waveforms. The oscilloscope should be
externally synchronized from pin 2 of V7 (through a 47 µF
capacitor to avoid disturbing the circuit.

7-5. SCHEMATIC DIAGRAMS.

7-6. The circuitry contained within each assembly is
shown in the schematic diagrams. These diagrams are
used to develop an understanding of the detailed theory
of operation of each assembly and as an aid in isolating
troubles within an assembly.

7-7. COMPONENT LOCATION DIAGRAMS.

7-8. The component location diagrams show the
physical location of parts mounted on an assembly.
Each part is identified by a reference designator.
115 V, 60 Hz
100 mA
100 mA