Is your vintage discman skippy and unwilling to play music smoothly ?
These are the "pots" controlling the laser movements.
RV501 - TG - Tracking Gain
RV502 - TB - Tracking Balance
RV503 - FB - Focus Bias
RV504 - PLL - Phase Locked Loop
RV505 - FG - Focus Gain
Make sure you mark their original position with a marker before modifying their settings!
My observations are:
TB and FB can be tuned without a oscilloscope(still better if you have one).
TB is the Tracking Balance, which is the parameter that maintains the laser head right above the "groove" on the disc(horizontal parameter). If the value of TB is to one of its extreme the laser will keep moving outward/inward. In this case, the laser head is no longer right on top of the "groove" of the disc, hence its behavior.
For coarse tuning, try to turn it slowly CW until the laser lose track of the groove, then turn it CCW until the same behavior. The middle point between these two extremes is where it should be. Tap the player slightly to see if it's moving out or in and adjust accordingly.
FB stands for Focus Bias, which controls the vertical movements of the laser. Same as TB, turn it slowly CW and you'll head a hissing noise coming out; turn it CCW for the same hissing sound. The point where there is the less acoustic noise it's where it should be.
AFAIK, PLL is NOT SOMETHING YOU CAN ADJUST WITHOUT A OSCILLOSCOPE! PLL stands for Phase Locked Loop, which controls the frequency. CD players use it to sync the spindle motor speed(my guess) and most of the time there's no need to adjust it. If you do the spindle motor might be aging.
Lastly, FB and TG shouldn't be touched as they are most likely optimized already, if turning them helps your CD player might mean the laser is aging and its signal/noise ratio changed greatly, considering the fact that these two "pots" have a margin(Service Manual).
In the end I want to thank the Stereo2Go forum, their members really helped a lot! And stay safe from the COVID-19!
Hope this helps with your music experience with your discman !
