TM 9-6625-1753-14
Table 5-3. Troubleshooting Dual Trace Plug-In Type 76-02A - Continued
Table 5-3. Troubleshooting Dual Trace Plug-In Type 76-02A - Continued
Malfunction
Probable cause
Corrective action
Malfunction
Probable cause
Corrective action
Defective transistors in the blanking
Replace Q9701, Q9702, Q9703, and
Beam position
indicator
doesn't
Defective transistor or component in
Replace
Q9504
or
the
defective
circuit.
Q9704 (fig. 5-7).
function.
the Q9504 stage.
component (fig. 5-9).
Defective electronic switch circuit.
Replace Q9600 and Q9601 or the
Defective beam position indicator.
Replace DS9501 or DS9502.
defective components (fig. 5-7).
NORM-INVERT switch in AC position
Defective dc blocking capacitor,
Replace capacitor C9115 for channel A.
doesn't block the dc component of
depending on the channel to be
Replace capacitor C9915 for channel B.
input signal.
displayed.
Trace can't be centered on either
Defective stage in the preamplifier
Check Q9205, Q9204, Q9203, Q9202,
channel when the POSITION
circuit.
Q9201, Q9200, V921, and V920 for
control is rotated.
channel A and replace the defective
component in these stages.
Check
Q9305, Q9304, Q9303, Q9302, Q9301,
Q9300, V931, and V930 for channel B
and replace the defective component in
these stages (fig. 5-7).
Defective POSITION control.
Replace POSITION control R9234 for
channel A and POSITION control 19334
for channel B.
Horizontal trace moves up and down
Defective paraphrase amplifiers.
Replace defective V920, V921 and their
as the VARIABLE control is rotated.
associated defective components for
Can't be corrected by adjusting the
channel A.
Replace defective V930,
DC BAL control.
V931 and their associated defective
components for channel B (fig. 5-7).
Defective dc balance network at the
Replace the defective network component.
grid of V921 or V931.
VARIABLE control has no effect, or
Defective VARIABLE control:
Replace control R9213 (channel A) or
doesn't cause a smooth change in
control R9313 (channel B).
the vertical deflection as it is
rotated.
Poor frequency response.
Defective stage in the preamplifier
Check Q9205, Q9204, Q9203, Q9202,
circuit.
Q9201, Q9200, V921 and V920 for
channel A and replace the defective
component in these stages.
Check
Q9305, Q9304, Q9309, Q9302, Q9301,
Q9300, V931, and V930 for channel B
and replace the defective component in
those stages (fig. 5-7).
Defective stage in
the
vertical
Check Q9409, Q9408, Q9407, Q9406,
deflection amplifier.
Q9405, Q9404, Q9413, Q9414, Q9403,
Q9402, Q9401, and Q9400 for both
channels and replace the defective
component in these stages (figs. 5-7 and
Internal triggering
doesn't
function
Defective
trigger
pick-off
amplifier
Check Q9501, Q9502, Q9503, Q9504, and
properly.
circuit.
Q9505 and replace the defective
Figure 5-6. Dual trace plug-in, left side view showing adjustments.
component in these stages (fig. 5-9).
5-5
