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DC Offsets on output - protection don't allowd to switch on

Yamaha RX-V765 Amplifier - DC Offset problem. - The amplifier is few month old and it was working well.
- Now protection switch off the amplifier during booting process - in moment when speakers' relay need to be switched on.
- The amplifier is possible to switch on with bypassing protection (I have Service Manual) and in this state the amplifier is working.
- Checking the history of faults inside service menu shows DC Offset problems.
- Measuring on the speakers shows different DC offsets on all channels (-0.250 V, +0.160 V, -1.270 V, +1.650 V,....).
All supply voltage inside the amplifier are OK.
It is very strange how DC Offsets on output of all 7 channels are to high without any serious damage.
Any suggestion how to solve this problem?
(Unfortunatelly I am not in position to use warranty because in my country doesn't exist Yamaha Service Center and I need to repair it myself). Thanks

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You don't want to do this( bypass the protection0
that d.c. output will burn the coils in your speakers with out making a sound!! you have a biasing problem
or like you said a d.c. offset problem it is best to work on this problem with out a load on the amp, this will allow you to trace back where the trouble is starting at. caps will cause this sort of problem but leaky transistors can also do this, even diodes.
this will require an experienced trouble-shooter.

Posted on May 27, 2010

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Posted on Jan 02, 2017

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