Nakamichi LX-3 Wont Play (but will FF and RW)

[mg007]

Hello everyone,


I’m working on a Nakamichi LX-3 that will FF and REW perfectly, but will not engage PLAY. When powered on, the mode cam motor runs and the arrow indicator moves from S (STOP) all the way to R (RECORD) and stays there. PLAY never engages.


The mechanism has been fully serviced:

• Complete disassembly and cleaning
• Relubed all moving parts
• New belts and idler tire
• Motors tested individually with external PSU (all good)

Currently, I’m testing the transport outside the chassis (mech grounded to frame), and I’m wondering if this is causing an interlock issue. It feels like the logic never sees the STOP/home position.


Observations:

• Cam motor runs continuously until it hits RECORD position. (When i try to move it maunaly it keeps fighting me to go back all the way)
• STOP position does not seem to be detected
• FF/REW always works

I suspect either:

• Mode cam timing is off?
• STOP microswitch? (didnt see one)
• Mode switch PCB not reporting correctly
• Or a grounding/record inhibit issue since the mech is out of the chassis

Before I start chasing logic ICs, I wanted to ask:
Does the LX-3 require the transport to be fully mounted for PLAY to work?
And is there a known procedure for re-timing the mode cam on this model?


Any guidance from those who’ve worked on Naks would be appreciated.


Thanks in advance.