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Sansui 8700DB green protector light keeps on blinking

Uwe.Weimer's picture

Does anybody has an Idea, how I get my sansui fixed.
Just checked all 5 fuses accessable lifting the top case, all ok.
Furthermore, all other funktions seem to work.
No unusual heat. But no sound.
No shortage on speakers. Was operating in low Volume mode.

Any help is highly appreciated.

Uwe



Re: Sansui 8700DB green protector light keeps on blinking

Some of these old Sansui units have fusible resistors that change value (higher resistance) than they should be. This could be resulting in enough DC offset to trip the protection circuit. Check R17 and R20 on the power amp driver boards, also make sure the voltages are correct from the regulated supply board.

Uwe.Weimer's picture

Re: Sansui 8700DB green protector light keeps on blinking

Many thanks IM3875, seems the resistors are ok. Now I brigged the Loudspeaker Relais....every thing works fine. Of course thats not what it should be because the safemode led keeps blinking, but now I can say its the speaker relais, which simply gets no power .... any idea to fix this issue under thos circomstances? Cheers Uwe

Re: Sansui 8700DB green protector light keeps on blinking

You are taking a big chance of damaging your amplifier or speakers when bypassing the protection relay. As stated, you need to find the problem; DC could be on the speaker lines. Check those for DC voltage; it should be very low--just a few millivolts.

Re: Sansui 8700DB green protector light keeps on blinking

The amplifier is staying in protect mode, which means there is a DC voltage on at least one of the audio output lines. It may be just a bias problem or there could be damaged audio output transistors or modules.