Tektronix 2445, Инструкция по эксплуатации

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TROUBLESHOOTING
Maintenance— 2445 Service
INTRODUCTION
Preventive maintenance performed on a regular basis
should reveal most potential problems before an instrument
malfunctions. However, should troubleshooting be required,
the following information is provided to facilitate location of
a fault. In addition, the material presented in the “Theory of
Operation” and “Diagrams” sections of this manual may be
helpful while troubleshooting.
TROUBLESHOOTING AIDS
Diagnostic Firmware
The operating firmware in this instrument contains diag­
nostic routines that aid in locating malfunctions. When in­
strument power is applied, power-up tests are performed to
verify proper operation of much of the instrument’s circuitry.
If a failure is detected, this information is passed on to the
operator in the form of either a crt readout or illuminated
LED indicators. The failure information directs the operator
to the failing block of circuitry. If the failure is such that the
processor can still execute the diagnostic routines, the user
can call up specific tests to further check the failing circuitry.
The specific diagnostic routines are explained later in this
section.
Schematic Diagrams
Complete schematic diagrams are located on tabbed
foldout pages in the “Diagrams” section. Portions of circuit­
ry mounted on each circuit board are enclosed by heavy
black lines. The assembly number and name of the circuit
are shown near either the top or the bottom edge of the
diagram.
Functional blocks on schematic diagrams are outlined
with a wide grey line. Components within the outlined area
perform the function designated by the block label. The
“Theory of Operation” uses these functional block names
when describing circuit operation as an aid in cross-refer­
encing between the theory and the schematic diagrams.
Component numbers and electrical values of compo­
nents in this instrument are shown on the schematic dia­
grams. Refer to the first page of the “Diagrams” section for
the reference designators and symbols used to identify com­
ponents. Important voltages and waveform reference num­
bers (enclosed in hexagonal-shaped boxes) are also shown
on each diagram. Waveform illustrations are located adja­
cent to their respective schematic diagram.
Circuit Board Illustrations
Circuit board illustrations showing the physical location
of each component are provided for use in conjunction with
each schematic diagram. Each board illustration is found in
the “Diagrams” section on the back of a foldout page, pre­
ceding the first schematic diagram(s) to which it relates.
The locations of waveform test points are marked on the
circuit board illustrations with hexagonal outlined numbers
corresponding to the waveform numbers on both the sche­
matic diagram and the waveform illustrations.
Circuit Board Locations
The placement in the instrument of each circuit board is
shown in a board locator illustration. This illustration is lo­
cated on the foldout page along with the circuit board
illustration.
Power Distribution Diagrams
Power Distribution diagrams (diagrams 11 and 12) are
provided in the “Diagrams” section to aid in troubleshooting
power-supply problems.
Circuit Board Interconnection Diagram
A circuit board interconnection diagram (diagram 13) and
tables listing the interconnecting pins and signals carried are
provided jn the “Diagram” section following the Power Dis­
tribution diagrams.
Grid Coordinate System
Each schematic diagram and circuit board illustration has
a grid border along its left and top edges. A table located
adjacent to each diagram lists the grid coordinates of each
component shown on that diagram. To aid in physically lo­
cating components on the circuit board, this table also lists
the grid coordinates of each component on the circuit board
illustration.
Near each circuit board illustration is an alphanumeric
listing of all components mounted on that board. The sec­
ond column in each listing identifies the schematic diagram
on which each component can be found. These component-
locator tables are especially useful when more than one
schematic diagram is associated with a particular circuit
board.
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