12.0
12.1
e
MODEL 415 ADJUSTMENTS AND MAINTENANCE
MAINTENANCE AND ADJUSTMENT
PROCEDURES
The Model 415 Sweep/Marker Generator
has been factory adjusted for optimum per-
formance and, because of its all solid state
construction and regulated power supplies,
does not require periodic calibration or
re-
adjustment. Because the instrument has
been designed to withstand severe mechan-
ical shock as well as electrical overloads
(All internal supplies are regulated and
have built-in short circuit protection), main-
tenance and repair requirements should be
minimal. If maintenance work is required
then possible readjustments may be
re-
quired if tuned circuits are involved or if
the circuit repaired requires a calibration
adjustment.
TROUBLESHOOTING INFORMATION AND
PROCEDURES
To aid in localizing possible problems the
functional block diagrams of Section 3 and
Section
4 of this manual are repeated. A
thorough review of Sections 3 and 4 of this
manual with reference to the accompany-
ing block diagrams will aid considerably in
circuit analysis. In addition to the block
diagrams and complete schematics, the fol-
lowing troubleshooting information is in-
cluded at the end of this section:
Figure 12.2. Parts layout for Marker, Wave-
form Generator and Pattern Amplifier Board
(Viewed from Component Side).
Figure 12.3. Parts layout for Power Supply/
R-F Board (Viewed from Component Side).
Figure 12.4. Parts Layout for Sweep Oscilla-
tor Board (Viewed from Component Side).
Figure 12.5. Parts Layout for Pix Oscillator
Board (Viewed from Component Side).
Figure 12.6. Waveform Generator Wave-
forms.
TABLE 12.1 Troubleshooting Chart
TABLE 12.2 Model 415 Switching Chart
TABLE 12.3 Transistor Voltage Chart
Because of the multiple outputs available
at the Model 415 front panel as well as the
control and switching functions performed
at the front panel, many problems,
if not all
trouble symptoms may be determined by
operation of various front panel controls
and observing that a required function
should result. Absence of a particular sig-
nal or output can then be used to analyze
the problem. Reference to the Troubleshoot-
ing Chart of Table 12.1 can be made to
localize the problem. As outlined in Sec-
tions 3 and 4 of this manual the FUNCTION
switch is used to activate certain stages as
required in each position as well as to com-
bine output signals in the desired sequence
so that the required output is generated at
the RF-IF-VIDEO jack. The Switching Chart
12.l.l
12.1.2
of Table 12.2 condenses this information
into compact form. By reference to the
Switching Chart as well as the functional
block diagrams and schematics, the defec-
tive signal path can be readily determined,
and from there the defective stage can be
localized. Voltage checks may then be em-
ployed to investigate a suspected stage.
There are certain basic circuits in the Model
415 which operate independently of the
FUNCTION switch and as a result can be
evaluated or analyzed without reference to
the FUNCTION switch position.
INTERCONNECTING CABLES, TEST
LEADS AND SWITCHES
Whenever an apparent loss of input signal
to the Model 415 or a signal from the Model
415 to external equipment (television re-
ceiver and oscilloscope) occurs the first
items to be evaluated are all interconnect-
ing cables. This is particularly true after the
unit has been in service for a considerable
period of time. Continued manipulation of
all test leads furnished with the Model 415
can cause intermittent or open leads which
may not be readily apparent, particularly
in the shielded cables. Another check to be
made before proceeding into the Model 415
circuitry proper is to check all connectors
and switches for proper operation. This can
be done by use of an ohmmeter with the
unit off, or, in the case of signal tracing,
this can be done by using an oscilloscope
to trace the signal either through a connec-
tor or through a switch.
If horizontal sweep is available at the
Model 415 and a scope is used for signal
tracing, the sweep selector of the oscillo-
scope may be left in the external sweep
position while signal tracing in the Model
415. In this way the observed wave forms
are always synchronized on the oscillo-
scope.
If it is desired to view the wave
forms at slower sweep rates select line sync
operation of the oscilloscope. Do not use
line sweep because this will distort the
observed waveforms.
REGULATED POWER SUPPLIES AND
BIAS SUPPLIES
The regulated 25 volt positive and negative
internal supplies of the Model 415 may
be
checked indirectly at the bias jacks of the
front panel. Both 0-25V bias adjustments
are connected across the internal regulated
supplies. Therefore, when each bias
ad•
justment is at maximum clockwise position
the voltage available at the bias jacks
~
equal to the internal regulated supply volt~
age. The positive and negative voltages
available at the 0-50V supply are unregu~
lated but may be checked in a simil~
manner at the corresponding bias jack. ·
I
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