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CTC210/211 Audio Troubleshooting
Setup for audio troubleshooting: · AF generator set to 1KHz @ 1Vp-p · Oscilloscope · External amplifier and speakers with aux or tape input.
No Audio any mode 1. Check audio outputs FIXED and VARIABLE for audio signal using oscilloscope or external amp and speakers. 2. Signal on FIXED out check U18100 and system control circuits. 3. Signal on VARIABLE out check U11900 and U11902 circuits and speaker switch (SW11900) 4. Check selected stereo output. 5. Connect AF generator to Digital TV audio inputs and select input source VGA2.
47 6. Check U11800-11, 15 for signal, no signal check generator and input circuit. 7. Check U11800-9, 19 for signal, no signal check U11800 and system control circuits. 8. Check U11800-7, 18 for signal, no signal check SRS circuit. 9. Check U11800-26, 27 for signal, no signal check U11800 and system control circuits. 10. Check U11800-3, 8 for 0Vdc (Speaker Mute) a high on either pin indicates speakers are muted. 11. Check mute circuits and system control. NOTE: At maximum volume, output from U11800 TVB is 900mv P-P. Signal levels that exceed 900mv P-P will damage the outputs. Tip: A problem in the AVR circuit can result in a reduction of volume. AVR Circuit Automatic Volume Reduction circuit is only active when volume is at or near max volume. The AVR circuit is protection that prevents over driving the outputs.