Troubleshooting; Isolating A Problem; Factory Repair; Before You Start - Wavetek 75 Instruction Manual

6.1 FACTORY REPAIR
Wavetek maintains a factory repair department for those
customers not possessing the necessary personnel or
test equipment to maintain the instrument. If an instru-
ment is returned to the factory for calibration or repair,
a detailed description of the specific problem should be
attached to minimize turnaround time.
6.2 BEFORE YOU START
Since no troubleshooting guide can possibly cover all
the potential problems, the aim of this guide is to give
a methodology which, if applied consistently, will lead
to the problem area. Therefore, it is necessary to
familiarize yourself with the instrument by reviewing the
functional description and the detailed circuit descrip-
tion (Section 4) in conjunction with the schematics
(Section 7). Successful troubleshooting depends upon
understanding the circuit operation within each func-
tional block as well as the block relationships.
WARNING
With the covers removed, dangerous voltage
points may be exposed. Contact with any of
these points could cause serious injury or
death.
The intent of this section is to provide the information
required to return this instrument to proper operation.
Information is divided into two parts. Part one contains
the overall instrument troubleshooting block diagram
(figure 6-I), which is useful in isolating defective blocks
within the instrument. Part two consists of a series of
circuit guides (table 6-I), one for each block shown in
figure
6-1
,
that provides settings and measurements for
troubleshooting an individual block. Also, each circuit
guide references related schematics, circuit descrip-
tions, and calibration procedures.
Before beginning the troubleshooting process, verify that
the instrument's controls are set correctly. Table 6-2
gives examples of possible symptoms that can be the
result of a setup error. For more information about the
instrument controls and operation, refer to Section 3 of
this manual.
Inspect the instrument's components, wiring and circuit
boards for damage. Finally, ensure that the ac fuse is
intact and the internal dc power supplies,
+
15 Vdc,
+
5 Vdc, and
+
10 Vdc, are good.
6.2.1 Isolating a Problem
To successfully troubleshoot this instrument, the
symptom must first be identified, the faulty block
isolated, the block analyzed, and the defective compo-
nent located and replaced.
To identify the symptom, use all of the front panel con-
trols and connectors. For example, if the sample fre-
quencycontrol is not working, are any other parameter
controls defective?
Once the symptom is identified, use figure 6-1 to isolate
the circuit block. After the block is isolated, refer to the
appropriate functional circuit guide (table 6-1).
The circuit guides provide some but not necessarily all
of the possible failure modes for a particular circuit.
Where applicable, an instrument setup is given to help
isolate the problem for a particular failure mode.
Paragraph 6.4 gives component troubleshooting
information.
NOTE
In the following tables, an expression like
"U33-5" refers to pin 5 of integrated circuit
U33. All pins on referenced integrated cir-
cuits and connectors are referred to in the
same manner.
Scans by ArtekMedia O 2006