The failure to left and right two channels at the same time, appears at the same time the speaker only considering the both sides of the same failure probability is small, so don't consider first reasons. It involve a wide range of audio circuit, audio from putting, audio format conversion, discriminator to audio processing, power amplifier circuit may sound distortion caused by failure. From AV input for narrowing the scope of fault diagnoses, the input video signal, the fault is still. On the basis of the fault area location part of the audio channel. The machine audio channels including TV/AV1 / AV3 switching circuit, the ball around the sound processing circuit, audio analog control circuits, subwoofer (XBS) circuit, audio power amplifier circuit, etc. (see figure 1). k4hservice manual download site
 k4hservice manual download site
Measurement of audio amplifier IC2301 (TA8200AH) each pin voltage basic normal, using oscilloscope to observe IC2301 L, R audio output 7, 12 feet of signal waveform, found in audio signal mixed with high frequency noise signal, and output signal waveform serious asymmetry of positive and negative half cycle. IC2301 input change test (2), (4), the signal waveform and output basic same, just smaller. Through the above checks, but the basic rule out the possibility of work into the circuit. k4hservice manual download site
 k4hservice manual download site
IC2301 work into the circuit of the input signal from V board connected to the terminal V1 (3), (4) feet, measuring the same two feet of signal waveform is not normal. While measuring V L, R signal input signal waveform V1 (5, 6 feet is normal. Measurement results, suggests fault on the V board. k4hservice manual download site
 k4hservice manual download site
This machine V board is a subwoofer (XBS) processing circuit, by three pieces of dual channel operation amplifier circuit (IC2351 - IC2353) and control circuit components (see figure 2). IC2351 and IC2352 (both for BA15218N) separately as two main road L, R and deputy (bass) audio signal amplification and hybrid tasks, and the deputy signal is through IC2353 (MB3110A) and balance control and amplitude control before sent to IC2351 and IC2352. Three pieces of IC power supply, all by V board V1 (2) feet input terminals of the 12 V voltage by the resistance of step-down, voltage regulator tube voltage again after 6 V voltage supply. Check the V1 (2) feet 12 v voltage is normal. Analysis, therefore, if the fault is produced by V board, may be caused by the power supply circuit or IC2353 (for IC2351 and IC2352 fault probability of the same smaller) at the same time.

 3    1 2 3 Next Last