Tektronix 7B92A Maintenance Manual page 46

and waveforms page adjacent to each
schematic diagram.
recommended test equipment, front-
panel control settings, voltage and
waveform conditions,
equipment cable connection instructions.
7. Check Individual Components.
following procedures describe methods for checking
individual components. Two-lead components that are
soldered in place are best checked by first disconnecting
one end.
This isolates the measurement from the effects
of surrounding circuitry.
CAUTION
To avoid damage, disconnect the power
source before removing or replacing
semiconductors.
TRANSISTORS. The best check of transistor
operation is actual
conditions. A transistor can be most effectively checked
by substituting a new component or one that has been
checked previously.
conditions are not such that a replacement transistor
might also be damaged. If substitute transistors are not
available, use a dynamic tester. Static-type testers are
not recommended, since they do not check operation
under simulated operating conditions.
INTEGRATED CIRCUITS.
voltmeter, test oscilloscope, or by direct substitution. A
good understanding of circuit operation is desirable when
troubleshooting circuits using IC.
checking voltages and waveforms around the IC so that
adjacent leads are not shorted together. A convenient
means of clipping a test probe to the 14and 16-pin IC is
with an IC test clip.
extraction tool. The lead configuration for the
semiconductors used in this instrument is shown on a
pullout page in the front of the diagrams section.
CAUTION
Do not use an ohmmeter scale that has
a high internal current.
may damage the diode.
REV A, JUN 1978
Note the
and test
performance under
However, be sure that circuit
Check with a
Use care when
This device also serves as an
High currents
or shorted condition by measuring the resistance
between terminals with an ohmmeter scale having a low
internal source current, such as the R X 1K scale. The
resistance should be very high in one direction and very
low when the meter leads are reversed.
The
indicated by a stripe, a series of stripes, or a dot. The
cathode and anode ends of metal-encased diodes are
identified by the diode symbol marked on the case. For
most silicon or germanium diodes with a series of
stripes, the color code identifies the four significant digits
of the JEDEC or vendor number using the resistor color-
code system.
ohmmeter. See the Replaceable Electrical Parts list for
the tolerance of the resistors used in this instrument.
Resistors normally do not need to be replaced unless the
measured value varies widely from that specified.
operating
checking continuity with an ohmmeter.
partially shorted inductors can usually be found by
checking the waveform response when high-frequency
signals are passed through the circuit. Partial shorting
often reduces high frequency response.
usually be detected by checking resistance with an
ohmmeter on the highest scale.
voltage rating of the capacitor. The resistance reading
should be high after initial charge of the capacitor. An
open capacitor can best be detected with a capacitance
meter or by checking that the capacitor passes ac
signals.
parts are located, follow the replacement procedures
given in Corrective Maintenance. Be sure to check the
performance of any circuit that has been repaired or had
any electrical components replaced.
4-7
DIODES. A diode can be checked for an open
The cathode end of each glass-encased diode is
RESISTORS. Check
INDUCTORS. Check for open inductors by
CAPACITORS. A leaky or shorted capacitor can
8. Repair and Adjustment.
Maintenance-7B92A
resistors with an
Shorted or
Do not exceed the
If any defective