How can this be? Sansui G9700 moving from SS

[jefferylhenr]

This 8700 totally responded by the book

 

[jefferylhenr]

What is the voltage across any single emitter resistor (i.e., R01-R04)?

Tro3 .05mv

 

[Leestereo]

Tro3 .05mv...

Is this voltage measurement on the emitter of TR03 (referenced to ground)? Or is it across the emitter resistor R03?

 

[jefferylhenr]

Is this voltage measurement on the emitter of TR03 (referenced to ground)? Or is it across the emitter resistor R03?

It’s across from one end of the resistor to the other

 

[GrisPato]

Yes that’s where I am getting 246mv and full response to the vr. When I connect to the emitters I get no response to the vr and 0.06mv after 5 minutes.

Wouldn't this be logical. If you have 246 mV at the base of your output the base-emitter is not conducting so you can not measure anything on the emitter resistor untill that's up to around 5-600 mV.

 

[jefferylhenr]

We have finally a happy ending. With the vr’s all the way counter clockwise there is essentially zero current. I had to turn them almost 3/4 of the way clockwise and boom we had liftoff. They are very touchy but got them both to 5mv

 

[ivandezande]

We have finally a happy ending. With the vr’s all the way counter clockwise there is essentially zero current. I had to turn them almost 3/4 of the way clockwise and boom we had liftoff. They are very touchy but got them both to 5mv View attachment 2534374

This is normal. I've had three.

 

[kevzep]

We have finally a happy ending. With the vr’s all the way counter clockwise there is essentially zero current. I had to turn them almost 3/4 of the way clockwise and boom we had liftoff. They are very touchy but got them both to 5mv View attachment 2534374

You should always replace any adjustment trim-pots in units this old.
They have more often than not been sitting in one position for a very long time, as soon as you move them they become intermittent and difficult to adjust, in some cases they have dead spots which can cause the bias to run away....

 

[jefferylhenr]

You should always replace any adjustment trim-pots in units this old.
They have more often than not been sitting in one position for a very long time, as soon as you move them they become intermittent and difficult to adjust, in some cases they have dead spots which can cause the bias to run away....

I always work them a few times and then watch them with an in-line current meter for a number of hours afterwards. After replacing a number of vr’s I don’t really see a huge difference. But I understand what you are saying, if you can’t get them to stabilize then replace.