Nakamichi OMS-7AII - Disc error

[df8cf]

Hi Salar

Sorry I forgot to answer you question where to source a KSS-123A.
You can get it at Gerner electronics (Gerner Electronics) - he's still offering refurbished devices. I talked to Ralf Gerner and he said he sold many of 'em and never had any return.
I assume that's not the Laser in my case either.
I'll nevertheless go back to the original one as anatech suggested, return all trimm-pots to their original position (fortunately I took some photos before I touched anaything) and try to diagnose.

Kind regards
Gerhard

[df8cf]

Hi folks

just wanted to give u an update on recent activities - to make it short: no succes so far :-(
I got a new, tested KSS-123 pickup and installed that, it behaved differently compared to original device as well as 1st replacement as follows:
1) the reference current departes significantly from the printed value (66.6mA - measure 61.9mA) - I'll check with my dealer
2) Manually "dialing in" the pick-up - the method I was successful to read in ToC with original pick-up as well as 1st replacement doesn't work
3) The player does no longer move the pick-up towards the end of the CD before "spitting it out" - interprete this as "FOCUS OK" not successful

My next steps will presumably focus on power supply - unless somebody is stopping me from doing that (I admit - I'm a bit afraid removing the main pcb assy) - why:
When seraching for the GND-pin close to FOCUS-TP to connect the scope I found that there's an impedance between chassis-GND and this GND-TP of ~2...3Ohm. Switching off the mains this "resistor" disappears. I tested all voltages and found +11V aren't exactly 11V but 10.4V, whereas -11V come out as exactly -11.0V. My interpretation is, that this is some worn-out cap, fooling the instrument by "lifting" the GND.

Does this sound reasonable?
Time to change the caps after 20+ years?

Thanks for any hints - keep u posted
Gerhard