Troubleshooting Equipment; Troubleshooting Techniques - Tektronix 2246 1Y Service Manual

Maintenance—2246 1Y and 2246 Mod A Service
components on the circuit board, the table also lists
the grid coordinates of each component in the
circuit board illustration.
Near each circuit board illustration is an alpha­
numeric listing of all components mounted on that
board. The second column in each listing identifies
the schematic diagram in which each component
can be found. These com ponent-locator tables are
especially useful when more than one schematic
diagram is associated with a particular circuit board.
Component Color Coding
Information regarding color codes and markings of
resistors and capacitors is located in the color­
coding illustration (Figure 9-1) at the beginning of
the Diagrams section.
RESISTOR COLOR CODE. Resistors used in this
instrument are carbon-film , composition, or pre­
cision m etal-film types. They are usually color
coded with the EIA color code; however, some
m etal-film type resistors may have the value printed
on the body. The color code is interpreted starting
with the stripe nearest to one end of the resistor.
Composition resistors have four stripes; these rep­
resent two significant digits, a multiplier, and a
tolerance value. Metal-film
stripes representing three
multiplier, and a tolerance value.
CAPACITOR MARKINGS.
common disc capacitors and small electrolytics are
marked on the side of the capacitor body. White
ceramic capacitors are color coded in picofarads,
using a modified EIA code.
Dipped tantalum capacitors are color coded in
microfarads. The color dot indicates both the
positive lead and the voltage rating. Since these
capacitors are easily destroyed by reversed or
excessive voltage, be careful to observe the polarity
and voltage rating when replacing them.
DIODE COLOR CODE. The cathode end of each
glass-encased diode is indicated by either a stripe,
a series of stripes or a dot. For most diodes marked
with a series of stripes, the color combination of the
stripes identifies three digits of the Tektronix Part
Number, using the resistor color-code system. The
cathode and anode ends of a metal-encased diode
may be identified by the diode symbol marked on its
body.
6-6
resistors have five
significant digits, a
Capacitance values of
Semiconductor Lead Configurations
Figure 9-2 in the Diagrams section shows the lead
configurations for semiconductor devices used in
the instrument. These lead configurations and case
styles are typical of those used at completion of the
instrument design. Vendor
formance improvement
changes of case styles or lead configurations. If the
device in question does not appear to match the
configuration shown in Figure 9-2, examine the
associated circuitry or consult a manufacturer's
data sheet.
Multipin Connections
This instrument uses two types of cable connectors.
The main type is an etched-circuit ribbon cable with
pin connectors crimped directly to the end of the
cable. The number one pin is indicated by a mark on
the ribbon cable. The other type of connector is a
plastic holder containing connectors crimped to the
ends of individual wires.
important, is indicated by a triangle (arrow).

TROUBLESHOOTING EQUIPMENT

The equipment listed in Table 4-1 of this manual, or
equivalent equipment, may be useful when trouble­
shooting this instrument.

TROUBLESHOOTING TECHNIQUES

The following procedure is arranged in an order that
enables checking simple trouble possibilities before
requiring more extensive troubleshooting. The first
two steps use diagnostic routines built into the
operating system of the instrument.
The next four procedures are check steps that
ensure proper control
operation, and adjustment. If the trouble is not
located by these checks, the remaining steps will aid
in locating the defective component. When the
defective component is located, replace it using the
appropriate replacement procedure given under
Corrective Maintenance in this section.
£ CAUTION
V T W W
Before using any test equipment to make
measurements on static-sensitive, current-
sensitive, or voltage-sensitive components or
assemblies, ensure
current supplied by the test equipment does
not exceed the limits of the component to be
tested.
changes and per­
changes may result in
Orientation, where
settings, connections,
k
W W ' S
that any voltage or