Sansui AU-9900 - Sudden chanel dropout

[LAUST9000]

Hi Forum,

New member here - would appreciate some sparring on a sudden channel dropout on my newly acquired Sansui AU-9900.

Unfortunately, I'm no DIY, but nevertheless, I would love to get some insights from the collective genius of you all...

The amp is new (to me). Had it for a couple of days. Never serviced, so I have already made plans for a recap.
It sounded wonderful - maybe a bit harsh in the highs. Maybe not full in the low register. But nonetheless it is playing. And I was pretty happy with that.

After two days one channel suddenly goes mute.
I have bypassed the preamp. Same result.

I can get both speakers to play by toggling the switch: MODE to L+R

Does this indicate any source of the issue to any of you?

MAN I was really enjoying this amp :-/

Would appreciate any feedback ...

Thanks,
Laust

 

[cademan]

First try cleaning all pots and switches with deox.

 

[LAUST9000]

First try cleaning all pots and switches with deox.

Thanks - will try this. However, this was done pretty extensively prior to my purchase.
I imagined that bypassing the preamp section (and still only sound in one channel) would indicate that switches are not the issue - is that a wrong assumption?

 

[cademan]

Open it up and see if any fuses are blown.

 

[LAUST9000]

Open it up and see if any fuses are blown.

Thanks for the feedback. At this point, I prefer to take it directly to the shop - and absorb the service 'damage' - jikes.

The fact that the MODE switch made it possible to get both channels going was just puzzling to me ...
Made me wonder if I can track the issue to NOT be transistors or other parts of the amp.
But I'm just not that skilled that I can understand the circuitry of this or any amp

 

[LAUST9000]

RESOLVED

 

[macyjrm]

Please share with us the how part to this story.

 

[LAUST9000]

I was hoping that I didn’t have to- but here goes

Since the amp was new to me and I wanted to give it an overhaul anyway I didn’t do too much troubleshooting. I didn’t want to risk further damage to the amp or speakers.

The tech didn’t manage to reproduce same issues, but I still left if for cleaning and recap.
Yesterday, I hooked up a headphone amp to my dac - and guess what: only sound in one channel.
The issue was a bad connector in the cable on the dac end.

well. You live and Learn.

 

[macyjrm]

We’ve all been there and done that. Glad you found the problem source. Your AU9900 is something really special.

 

[LAUST9000]

Thanks
I got two full days of listening to the AU-9900 before sending it off to recap. Even though I could tell the high notes were a bit fuzzy I still was enjoying it very much.
I’m so pleased this forum opened my eyes to the Sansui universe.