onkyo TX-SV535

[Carlosraj]

Hi,

I am working on this amp to rectify its problem. When I press the standby switch , after about 2 secs , the power relay turns ON. Then about 2 to 3 secs later the speaker relay turns ON, then turns OFF,ON, OFF and then remains ON but there is no sound. If I turn the volume up above half way and onwards, there is sound but badly distorted. I have checked all the power transistors, small transistors and other components on the power amp, and they all seem OK. I have replaced all the four BA15218 ICs and the volume IC (TC9213) on the master volume board. All the voltage regulators are also OK. I cannot figure out what could be the problem. Can someone please assist.

Thanks

Carlos

 

[JonSnell Electronic]

Check the output transistor centre voltages for zero. If not zero fault find the channel that is incorrect.

 

[Carlosraj]

Check the output transistor centre voltages for zero. If not zero fault find the channel that is incorrect.

You mean the centre voltage at the 2 power supply filter caps. How do I check the output transistor centre voltage. Pls advice

Thanks

 

[JonSnell Electronic]

Check the DC voltage between the centre of the two power supply capacitors and each of the output junctions, (loudspeaker outputs before the relays). The must all be zero.
The service manual shows the junctions.

 

[Carlosraj]

Check the DC voltage between the centre of the two power supply capacitors and each of the output junctions, (loudspeaker outputs before the relays). The must all be zero.
The service manual shows the junctions.

Thanks, will do.

Carlos

 

[Carlosraj]

Thanks, will do.

Carlos

Dear Jonsnell,

The voltage between the centre of the filter caps to the main speakers output transistors read about 0.81V and to the output of the rear speakers transistors read about 1.15V. Is this normal or if not what could possibly be the cause.

Thanks

Carlos