Tektronix T922 User Manual

NOTE
Service Information-T921/T922/T922R
Fig . 5-4 . Multi-connector holder orientation .
6 . Check Voltages and Waveforms . Often a defective
component
can be located by checking for the correct
voltages and waveforms
in a circuit .
Voltages and
waveforms given on the diagrams are
not absolute and therefore
may vary slightly
between instruments . To obtain operating
con-
ditions similar to those used to take these readings,
see the voltage and waveform setup procedures in
the Diagrams section . Individual deviations should
be
noted
on the schematics for future reference .
7 .
Check the individual components . Remember that
the best check
of semiconductors-transistors, diodes,
IC's-and thick film resistors
is actual operation in a
circuit . If you suspect that a semiconductor
is bad,
substitute a new one for it . Before you start checking IC's,
read the part of the Circuit Description that covers the
circuit .
WARNING
The
power switch must be turned off before
remov-
ing or replacing
components to prevent electrical
shock or
circuit damage .
To check other
components, resistors, capacitors and
inductors, clip one lead and lift
it . You may have to add a
piece of wire when you resolder the connection,
however .
Resistors : Check the
resistors for discoloration . Then
check the resistors with
an ohmmeter after disconnecting
5- 8
oneend from the circuit . Check the 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 the specified value .
Inductors : Check for open inductors by checking
continuity with an ohmmeter . (It
may be
helpful
to
disconnect one end of the inductor when checking
continuity .) Shorted or parially shorted inductors can also
be
found
by checking the waveform response when high-
frequency signals
are passed through the circuit . Partial
shorting often
reduces high-frequency response (in-
creases roll-off) .
Capacitors : A leaky or shorted capacitor can be
detected
by checking resistance with an ohmmeter, on the
highest scale, after
disconnecting one end from the
circuit . Do not exceed the voltage rating
of the capacitor
(some ohmmeters use 30 volts
as source voltage) .
The
resistance reading should
be
high
after initial charge of
the capacitor . An open
capacitor can also be detected with
a capacitance meter or by checking whether the capacitor
passes ac signals .
Switches : The most common cause of switch failure is
dust
between the contact and the pad . Check the
suspected contact for
continuity with an ohmmeter . If
open and not obviously damaged, try cleaning (see Cam
Switch Repair and Replacement) .
Another frequent cause
of switch failure is solder
smoke residue . This can occur when replacing a
compo-
nent near the switch . This problem is usually indicated by
reduced high-frequency response . Flushing the contact
with isopropyl alcohol usually fixes this problem .
If the contact is physically
damaged, replace the
contact strip . Bending the contact is only a temporary
repair . See Cam Switch Repair and Replacement .
8 . After
repairing a circuit or replacing components,
check the
performance of the instrument . If the Perfor-
mance Check is within specifications, it is not necessary to
re-adjust the instrument .
If the instrument does not meet
the specifications, perform the
Adjustment Procedure in
Section 4 .
Troubleshooting Hints
Power . SYMPTOM-No visible trace and no display
when the BEAM
FINDER button is pushed (Power ON
lamp
is lit)
.
REV . A, JUNE 1976

Tektronix T922 Specifications

General

Brand	Tektronix
Model	T922
Category	Test Equipment
Language	English