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SERVICE MANUAL 66 cm CTV Effective: JANUARY,1995 CTM715SERV TEAC AUSTRALIA TECH MEMO #TV# 05.08.94 Model: CTM511/5S, CTM631/5S, CTM711/5S - Stereo Televisions Symptom: The instability of the Stereo Identification Signal on some high quality live stereo TV programs will cause split-second Sound distortion that may be confused as `Sibilance'. Replacement of C015 will improve filtering of the ID signal and remove any interference causing the effect. Stereo LED indicators may or may not switch off when distortion is audible. However, re-transmitted programs from overseas, movies and alike will not show any symptoms. Instruction: Incoming RF signal must be clean, high quality live transmission to verify if a TV is effected (use the NEWS or ABC Kids programs for example). Check Stereo ID signal (~117.5Hz) present on [TP001] Pin 5 of TDA 3803A (IC001). The sinewave found should be at least 7.0 Vpp (AC) and may vary slightly in amplitude from station to station. Instability of this wave is synchronised with speech and music and will show as a milli-second collapse. Carefully remove Stereo PCB, disconnection all connectors and the link to the main PCB (going to R633). Replace C015 from the original 10nF with a 1nF Capacitor . Reconnect all connectors and the link, check [TP001] again. Distortion on [TP001] must be peaked to its V. rising shoulder. maximum amplitude with T001 and thereafter readjusted to a more stable waveform with a shoulder distortion, as shown typically 6.5Vpp and Perfect symmetrical 8.5ms , (use a suitable waveform on negative adjustment tool and half do not readjust any other T potentiometers on the Stereo PCB). Please note that the correct adjustment of T001 must result in a distinctive `shoulder distortion' on the positive rising