Sansui G9700 bias setting?

[blhagstrom]

Anyone know what the bias setting is on the G9700?

Service manual has typo.
Says DC +/-5mv

Saw some posts saying 5mv but -5mv is 0v which can’t be right.

 

[kevzep]

Yeah 5mV is what I dialled my one to. Power it up, let it warm up for about 10-15mins then set it to 5mV and make no further adjustment. Put the lid on you're done.

 

[The Fuxtor]

Anyone know what the bias setting is on the G9700?

Service manual has typo.
Says DC +/-5mv

Saw some posts saying 5mv but -5mv is 0v which can’t be right.

That is weird? 5mV but +or- 5mV? If it's minus, there's no voltage? Wouldn't that equate to no bias???

 

[Skywatcher]

Anyone know what the bias setting is on the G9700?

Service manual has typo.
Says DC +/-5mv

Saw some posts saying 5mv but -5mv is 0v which can’t be right.

Saki will do that to you when writing up the service manuals. Sansui must have had a few Saki Suckers doing the service manuals...

 

[Hyperion]

Looks like they are (for once) helpfully saying that it is the 'magnitude' of the bias voltage measured that is important, not the 'sign'. Although they do clearly indicate meter polarity for connecting to the bias test points.

Sansui falling over themselves to be helpful is very offputting.

 

[LBPete]

The Bias setting is indeed 5mV on these receivers. It's not a typo. If you look in the schematic, it's called out there too.

- Pete

 

[LBPete]

Here's a clip of the schematic showing 5mV across the emitter resistors.

- Pete

 

[blhagstrom]

Here's a clip of the schematic showing 5mV across the emitter resistors.

- Pete

Bingo,

I went looking through the schematic for it but I couldn't see it.
Potato eyes.

Thanks Pete.

So, that works out to 7ma. Seems low, but I'll go with that.

Still hunting toast. 6 outputs and 6 emitters were blown.
Got board damage, I think I have that fixed up.
I see toast on the driver boards so still in the woods.

 

[kevzep]

Bingo,

I went looking through the schematic for it but I couldn't see it.
Potato eyes.

Thanks Pete.

So, that works out to 7ma. Seems low, but I'll go with that.

Still hunting toast. 6 outputs and 6 emitters were blown.
Got board damage, I think I have that fixed up.
I see toast on the driver boards so still in the woods.

Yes it does seem low, but that is where the optimum setting is, trust me you don't want to poke the bear here with this as it will bite you, and not in a good way....

 

[blhagstrom]

Yes it does seem low, but that is where the optimum setting is, trust me you don't want to poke the bear here with this as it will bite you, and not in a good way....

I wouldn’t second guess the schematic.

I have evidence on the bench of the destruction that can occur in these. I’m hoping this one can be saved.

 

[kevzep]

I wouldn’t second guess the schematic.

I have evidence on the bench of the destruction that can occur in these. I’m hoping this one can be saved.

Except the G7700 SM where it says to set the bias to 5VDC!! I wonder if anyone even tried that?

But yeah, as you well know, always pays to be cautious with the High Speed DC Sansui's.....they can all be saved for sure...

 

[LBPete]

This 5mV spec has been discussed and argued many times over the years in the Sansui forum.

- Pete