Section V
5-36.
TROUBLESHOOTING
PROCEDURES.
5-37.
FRONT
PANEL
PROCEDURE.
5-38.
Use
an oscilloscope to monitor the following
checks. Record the results
of
each step for reference.
a.
Set the Model 209A frequency to 2 x
lOOK,
turn the sine wave amplitude fully
CW,
and
check for a sine
wave
output.
If
the sine
wave
is
clipped, record this.
b. Check the sine wave output on each range.
c.
Check for a 4.8 V
POp
sine wave sync output
at 1 kHz.
d. Check for a 20 V
Pop
square
wave
output,
symmetrical around 0
V.
5-39. Compare the results
of
the preceding steps to
Table 5-6 to help locate the trouble.
Model209A
540. DETAILED
CIRCUIT
TROUBLESHOOTING.
541.
The Oscillator Schematic Diagram, Figure 7-1,
shows dc voltages normally found throughout the
instrument. These voltages were taken with the
AGC
ADJUST R24 turned fully
CCW.
This disables the
oscillator. The voltages were taken with a battery
operated dc voltmeter, -hp- Model 427A. When
making these measurements, be sure to connect the
jumper between the chassis section where the tuning
capacitor
is
mounted and the tab just below it.
542.
The Oscillator Amplifier may be disabled by
turning
AGC
ADJUST R24 fully counter-clockwise.
A one volt rms sine
wave
from an external source
may now be injected into the gate
of
Al
Ql.
The
various stages
of
the amplifier may now be monitored
with an oscilloscope for proper operation. The
amplifier should have a gain
of
three for
all
frequencies up to 100 kHz.
543.
For detailed circuit theory
of
operation, refer
to Section IV
of
this manual.
Table 5-6. Front Panel Symptoms
Sine
Wave
Sync Square
Wave
Output
Output Output Action Required
Normal Normal
Normal Do Performance Checks
Clipped
Normal
Low Amplitude Troubleshoot Power Supply
Clipped or
Normal Normal Troubleshoot Buffer Amplifier
Missing
Normal
Normal Abnormal Troubleshoot Sine-Square Converter
No
Output
No
Output
No
Output Troubleshoot Oscillator Amplifier
All
outputs abnormal on one or more ranges Troubleshoot Range Switch Assembly
and Negative Feedback Circuit
5-8
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