Sansui 9090 no signal on left channel

[jervz]

I have not used my Sansui 9090 for several months. I connected it today as stand alone and with a pre-amp but left channel doesn't have
any signal or sound in Stereo mode. Speaker is good as the left channel works in "Mono" mode without the pre-amp.

What could be the issue? Is this something I can fix or it has to be serviced by a professional/technician?

Also, is it correct that I've connected my preamp at the main in of the Sansui 9090 instead of the pre-out? I don't get any signal if I connect the preamp via preout.

 

[Aud10file]

Sounds like there’s an issue in your power amp section.
Depending in when your unit was built, it may need a few modifications as per Sansui service bulletin SSI-0004E.
I’ve had a couple 9090 come through here and one had all the mods done by a previous person, but they were poorly done and it caused an issue in the power amp section.
The other had none of the mods and failed due to the missing mods.
Here’s a picture of a damaged relay in that second one. Luckily that was the only damage.



IMO, these are best done by an experienced person.

Check out xraytonyb’s channel on youtube to get an idea of what is involved in bringing one if these up to par.

 

[LBPete]

If you get sound from both channels when the mono button is pushed, there is nothing wrong with the amplifier section. As is usually the case, the dropout is occurring in the preamp at a point in the signal path before the mono switch. The mono switch simply connects Left and Right channel pre amps together.

- Pete

 

[Aud10file]

I believe I may have misread the description @jervz posted above. Glanced right over the mono part. @LBPete is correct.

 

[Got Midbass?]

Rotate the tape selector switch a few times. Mine had that issue. Hope it helps.

 

[LBPete]

Yes, "exercise" all the controls on the front panel. The audio path goes through almost all of them.

- Pete