at first my Technics SU-5 Stereo Amp's Phono stopped working which refrained by turntable to give its output now recently its "left" speaker started emitting whistling sound, I switched the speaker from right to left and left to right. again after playing radio/tape for couple of minutes same whistling sound started from the speaker connected with the left channel. I disconnected the left channel speaker the sound now comes from the right channel speaker perfectly satisfactorily.
please suggest how to address to overcome both the above issues so that the amp is back to normal
please suggest how to address to overcome both the above issues so that the amp is back to normal
You need to give us some more information in order to locate the source of the left channel oscillation. It is unusual to have audible oscillation but realising this is quite an old amplifier (1982), it's likely that electrolytic capacitors in the preamplifier sections have failed and this could be causing unstable circuit operation.
Before proceeding to check out the internal electronics, does the oscillation stop when you disconnect the phono inputs or switch to another input source such as a tuner, media player, CD player etc? Does it stop in any other configuration - even when there is no signal connection at all or the inputs are simply shorted to ground (i.e. from centre pin location hole to outer shell)?
As one channel is still OK, there may be some help there in comparing DC voltages between similar circuit nodes in both channels, if you have a digital multimeter and you know how to use it safely - meaning with due care and precautions like sharp or hook probes, to avoid shorting what you are testing to other points of the circuit and so causing more serious damage or injury to yourself.
As a general consideration before going further, are you familiar with electronic components, circuits etc? If not, it might be wise to seek assistance from someone who is and also has suitable test gear. A technical service manual is available here, after registering with the site.
Before proceeding to check out the internal electronics, does the oscillation stop when you disconnect the phono inputs or switch to another input source such as a tuner, media player, CD player etc? Does it stop in any other configuration - even when there is no signal connection at all or the inputs are simply shorted to ground (i.e. from centre pin location hole to outer shell)?
As one channel is still OK, there may be some help there in comparing DC voltages between similar circuit nodes in both channels, if you have a digital multimeter and you know how to use it safely - meaning with due care and precautions like sharp or hook probes, to avoid shorting what you are testing to other points of the circuit and so causing more serious damage or injury to yourself.
As a general consideration before going further, are you familiar with electronic components, circuits etc? If not, it might be wise to seek assistance from someone who is and also has suitable test gear. A technical service manual is available here, after registering with the site.