TROUBLESHOOTING
continued
If there is no video on the CRT, check for a video waveform at
TP12.
If video is present at TP12:
Refer to the “Video” section of this Troubleshooting guide.
If there is no
at TP12:
Check the voltages, waveforms, and components associated
with IF Module
and AGC Mute Transistor
A defective AGC circuit can cause an overloaded picture, excessive
snow or loss of audio and video.
See the AGC Voltage Chart for AGC voltages with signal.
AGC Voltage Chart
IF201
pm 1
SYNC
If there is no vertical or horizontal sync:
Check the voltages, waveforms, and components associated
with Y Buffer Transistor (4301).
If there is no vertical sync:
Check the voltages, waveforms, and components associated
with pins 38, and 44 of Y/C/J
1 Transistor
2 Transitor
and
3 Transistor
If there is no horizontal sync:
Check the voltages, waveforms, and components associated
with pins 41, and 45 of
VIDEO
Inject a signal at
and check for video on the CRT
If video is present:
Refer to the
section of this
guide.
If there is no video on the CRT, check for a video waveform at pin 6
of Comb Filter (CM1301).
If video is missing at pm 6 of CM1301:
Check the voltages, waveforms, and components associated
with Buffer Transistors
and AV-Switch IC
and CM1301.
If video is present at pin 6 of CM1301, check for a video waveform
at the emitter of Y Amp Transistor (4305).
If the video is missing:
Check the voltages, waveforms, and components associated
with 4305, Buffer Transistor
and Y Switch IC
If the waveform is present at the emitter of
Check the voltages, waveforms, and components associated
with pins
and of Y/C/J
Buffer
Transistors
Gamma Comp 1 Transistor
and Equalizer Transistor
Y Clamp Transistor
and Gamma Comp 2 Transistor
If brightness is inadequate or
be
Check the voltages, waveforms, and components associated
with pin of
Check for a chroma waveform at pm of Y/C/J IC
If the waveform is missing:
Check the voltages, waveforms, and components associated
with Buffer Transistor
C-Switch IC
and pin 4
of Comb Filter (CM1301).
If chroma waveform is present at pin of
1, cheek for the
er waveforms at pins
of
If these waveforms are missing:
Check the voltages, waveforms, and components associated
with pins
thru 25 of
Check the
oscillator at pin 7 of
If the proper wavforms are present at pins
of
Refer to the “Raster” section of this Troubleshooting guide.
RASTER
Check the CRT and CRT voltages. Cheek the voltages, waveforms,
and components associated with Buffer Transistor
SW 1
Transistor
and SW 2 Transistor (4712).
If there is no Red:
Cheek the voltages, waveforms, and components associated
with pin 20 of Y/C/J IC
Red Output Transistor
Video Amp Transistor
and Red
Det Transistors
16).
If there is no Green:
Check the voltages, waveforms, and components associated
with pin 22 of
Green Output Transistor
Video
Amp Transistor
and Green
Det Transistors (4706,
15).
If there is no Blue:
Check the voltages, waveforms, and components associated
with pm 24 of
Blue Output Transistor
Video
Amp Transistor
and Blue
Det Transistors
14).
If the raster has a keystone shape:
Check the Deflection Yoke
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