pioneer sx 1980 low bias on one side.

[Jimbo40]

I have a very nice original 1980 works great.
Today I was checking dc balance and offset and offset is now at L .5 mv R 3.1
And bias or balance was 30.5 mv L and 1.9mv R
I adjusted R to 30.5 mv and all seems well but how could that channel run with bias being so low?
Turning clockwise it went right up to where I want it. Still sounds great.
Anyone know?

 

[ivandezande]

Confused as to what you mean, it could run fine at that level but I'm sure distortion was pretty bad in comparison to when bias is at the correct value.

 

[Jimbo40]

Well it sounds excellent now, I thought it sounded great before, no detected distortion.
I thought the transistors needed 30 mv for proper operation.
Before correction both heat sink were about the same temp.
I didn't know they could be that far off. When I run it for a while hard mv's move down to about 20mv both sides.
Should it be 30 mv hot? And not worry about cool mv?

 

[Robisme]

Adjust it per the service manual. Does is say to wait a certain period of time before adjusting?

Also, it will work with low bias, there would just be distortion at very low volumes if it's too low.

Rob