Sony Integrated Amplifier TA-AX295 distortion.

[exact55]

I have aquired a Sony TA-AX295 integrated amplifier (circa 1990) as part of a system.
The amplifier distorts badly even at fairly low volumes on all input channels. The VU meters show that the signal is being overdriven at normal input levels. Even at very low input levels the audio is clipping although the VU is normal. I assume that this is happening in the pre-amp somewhere. Does anyone have any experience with these amps that will point me in the right direction. I have been unsuccessful in finding a service manual or schematic.

I'm pretty handy with a soldering iron although my expertise is in digital electronics and not audio. I am thinking of replacing all of the electrolytics, but I may be way off. Any help with advice or schematics etc. will be greatly appreciated.

Regards
Kasper de Bruin

 

[rexter]

http://www.mauritron.plus.com/html/sony_-_t.html

I'm not sure if it's the capacitors is the problem on your system, It's highly unlikely that all capacitor get bad at the same time. But that could happen too. If the capacitors are bad then by your description, it would be where the power amp is. Therefore I would assume it's the IC however or transistors.

For easy testing is a walkman connected to one of the input and try to control the input volume level.

If it works, an easy fix is to get a variable resistor (potentiometer) and connect it into the input then adjust is till you get the proper value of the resistance needed (of coarse you need to construct an inline cable). All that is needed is to solder the same resistor value to an input but the phono and digital in into the board.

Another solution is to trace the connection from the input to the preamp, which is time consuming without the diagram. Even that will not be a guaranty fix if you can't find the failed parts. And analog VOM is a better equipment to use on this kind of trouble shooting with digital as a secondary tool to find the polarity, but if you have an Oscilloscope then that'll make your troubleshooting pretty easy.

Higher grade AMPS comes with 6 pins IC near the input to regulate the signal before getting to the preamps. But in most cases just trace the input core line that lead to a larger IC.

Good luck with you findings.