Maintenance-2225 Service
1
1-kn range. The diode resistance should be very
high in one direction and much lower when the meter
leads are reversed.
Silicon diodes should have 0.6
V
to 0.8
V
across their
junctions when conducting; Schottky diodes about
0.2
V
to 0.4 V. Higher readings indicate that they are
either reverse biased or defective, depending on
polarity.
RESISTORS. Check resistors with an ohmmeter.
Refer to the Replaceable Electrical Parts list for the
tolerances of resistors used in this instrument. A
resistor normally does not require replacement
unless its measured value varies widely from its
specified value and tolerance.
INDUCTORS. Check for open inductors by checking
continuity with an ohmmeter. Shorted or partially
shorted inductors can usually be found by checking
the waveform response when high-frequency signals
are passed through the circuit.
CAPACITORS. A leaky or shorted capacitor can best
be detected by checking resistance with an ohm-
meter set to one of the highest ranges. Do not
exceed the voltage rating of the capacitor. The
resistance reading should be high after the capacitor
is charged to the output voltage of the ohmmeter. An
open capacitor can be detected with a capacitance
meter or by checking whether the capacitor passes
ac signals.
10.
Repair and Adjust the Circuit
If any defective parts are located, follow the replace-
ment procedures given under Corrective Main-
tenance in this section. After any electrical
component has been replaced, the performance of
that circuit and any other closely related circuit should
be checked. Since the power supplies affect all
circuits, performance of the entire instrument should
be checked if work has been done on the power
supplies or if the power transformer has been
replaced. Readjustment of the affected circuitry may
be necessary. Refer to the Performance Check and
I
Adjustment Procedure, Sections 4 and 5 of this
manual and to Table 5-1, Adjustments affected by
repairs.
CORRECTIVE MAINTENANCE
IN'TRODUCTION
2.
Verify that the line-rectifier filter capacitor
(C900) is discharged prior to performing any
Corrective maintenance consists of component
re-
servicing.
placement and instrument repair. This part of the
manual describes special techniques and procedures
3.
When soldering on circuit boards or small in-
required to replace components in this instrument. If
sulated wires, use only a 15-watt, pencil-type
it is necessary to ship your instrument to a Tektronix
soldering iron.
Service Center for repair or service, refer to the
Repackaging information in Section
2
of this manual.
OBTAINING REPLACEMENT PARTS
MAINTENANCE PRECAUTIONS
Most electrical and mechanical parts can be obtained
through your local Tektronix Field Office or
represen-
I
To reduce the possibility of personal injury or instru-
tative. However, many of the standard electronic
ment damage, observe the following precautions.
components can
usually be obtained from a local
commercial source. Before purchasing or ordering a
1.
Disconnect the instrument from the ac-power
part from a source other than Tektronix,
Inc., please
source before removing or installing
com- check the Replaceable Electrical Parts list for the
ponents.
proper value, rating, tolerance, and description.
6-1
0
REV
APR
1990
Scans
by
AR
TEK
MEDL4
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