Rock-ola 453 potentiometers on 48350 amplifier

[nickog]

Greetings all. Have a question about the Rock-ola Amplifier (48350-1A) internal adjustments. I have a Rock-ola 453 Jukebox. Recently I had to re-cap the amplifier as it started making a loud burping noise upon start up. You can watch me Re-cap it at the link at the bottom. Took about two hours to do and it made a world of difference in sound, and I did not think it had bad sound before.
Upon looking inside I saw that the right and left driver boards have two potentiometers on them. I am a little confused as to what they do. After putting the amp back together I realized that one channel seems to be putting out more that the other. Gain does not seem to help much. So that leads me to think these might need adjusting, but I am unsure what they would do. The schematics list one (red knob R14LR) as Output stage center voltage adjustment and the other (yellow knob R20LR) as Output stage Idle current adjustment. What would these do if I adjusted them? Looking back at my pictures it appears as the left side has the knobs turned a bit less that the right. Not able to find much information about these doing a google search. Any information would be welcomed.
Thank you so much.
Nick.
Re-cap it Here

[jukenorman]

Hi Nick,
You know the saying "when all else fails, look in the manual" lol! In this case, page 69 - these are the bias adjustments and shouldn't require touching unless output or driver transistors have been replaced.

Norman.

[nickog]

Hi Norman,

Thank you for your reply! That was exactly what I needed to know. Looking up biased / biasing gave me more information on the subject matter.
Awesome!
Thank you and have a good evening.

Nick.

[nickog]

So an update. Sound was still less on the left channel. After observing its behavior and realizing that whenever I'd go into the machine the sound would come back only to go away again whenever it felt like it. Started poking around the amp, I came to the balance control and the sound sprang back. It was the balance control that was the issue. Contact cleaner cleaned it up right away. Sound is even on both sides. I feel it even helped the right channels sound output too.