Laser Adjustments: KSS-151A in TEAC VRDS-10 vs TASCAM CD-401 MkII

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Hi guys,

I adjusted my VRDS-10 years ago and it still works flawlessly.
Owner of a spare player, a TASCAM CD-401 Mk II with a KSS-151A laser, I've looked for the FSM in vain. I've decided to use the VRDS-10 FSM, as the servo circuit seems to be the same. ICs and TP are the same.

All the adjustments can be done properly, they all match and behaviour like in the VRDS-10 but the Focus Gain only. Tracking Gain is fine.
When OK, the signals measured from the player are -90° phase shift. Sounds a bit odd as in the FSM just say a "phase is 90°" but works fine, guess they want a 90° between and that's all.
But no way for the FG in the TASCAM, 90° can be achieved by the pot turned in full, nonsense for a pot, and then the player is noisier than a jet plane but works fine anyway. That's not the proper adjustment. The only way to get it at the point it just become silent is when I look for a 45° phase shift. Or said in another way, somewhere with the pot closer to the middle, if I choose 45° (a pure guess) then it's quite silent and works fine. A tad "less" pot turning and it becomes noisy (one can hear the sine wave injected), a bit "more" and it will spins like crazy.

FSM, tech tips or experience to share anyone?

edit: I have played with toys and once things went right, don't know why, maybe the signal gen (cheap eBay thing), maybe the player (setting or such with power on/off?) maybe the scope... user!
If any idea I'll have a look, else I'll check again to see what (who) went wrong and that's it :)
 

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