What could be the cause of he 2 pots not to adjust to the 0 V on the one, and 50MV on the other? Is there a wait time after the unit is turned on before these adjustments should be made?

From what I've read in different threads, you should wait about 10 minutes after powering up, to get accurate dc offset readings. I also understand that the readings will fluctuate some based on the heat generated by the unit.

As the transistors warm up, they shift in characteristics. We usually give it a little while to stabilize after turnon before making adjustments ( we watch it to see when it settles) an dthen set them, but that's just the setting at THAT temperature, and it will change, which we watch, and wait ( up to 1/2 hour) and then try to adjust closer as needed.

There will be a point where the change in the setting is small enough that there will be minimal differences to settle out.

Sometimes as I watch it, I see it climbing towards an overshoot and back it down. Takes both patience and experience....

Patience will GAIN you experience...

Is there a better procedure, other than the one in the service manual, that gives more info?

I think markthefixer pretty much explain that. I also think the service manual is pretty self explanatory(at least it works for me for I have SX-1010 too). If you can get the dc offset close to 0mv and bias as close to 50mv with a fluctuation of a few millivolts then you should be fine. The fluctuation by a few millivolts is normal.

There must be different service manuals, as the one I have just gives a short explanation of the Bias and Offset.

There must be different service manuals, as the one I have just gives a short explanation of the Bias and Offset.

You are right, the earlier Pioneer manuals were a bit terse. There have been many manuals written since then and Pioneer got better at writing them.

The sx-1050 would be the next model series up several years later, then the 1080 etc...

they were: x2x , 424, 525, 626, 727, 828
x3x: 434, 535, 636, 737, 838, 939, 1010
x50: 450, 550, 650, 750, 850, 950, 1050, 1250
x80: 480, 580, 680, 780, 880, 980, 1080, 1280, 1980
??: 3400, 3500, 3600, 3700, 3800, 3900
sx-d5000, sx-d7000

Some of them SLIGHTLY better explain the heat drift rechecking / resetting.

The regulated power supply board must be restored before you can set a completely reliable setting, especially for offset.

The adjustment trimpots do go bad. Piher (avail. through Mouser) makes excellent replacements.

Finally, the differential amplifier transistors must be matched to within 5%.

Fred