Rebuilding a Nakamichi 600II
From NakTalk, May 2006:
My recently eBayed 600II is nearly dead. When I first played a tape, it played for about a minute. Then it stopped.
I tried rewinding, and did so for 5 seconds. Then it stopped. I turned it off, left it for a couple of hours, tried again, would not play, rewinded for 5 secs, to never move again. I have tried giving it a good cleaning, including the mechanical contacts (start SW, mute SW), checked supply (-0,7V, 11.5V ad 18V) and seemed fine, belts look fine, pressure roller looks fine, capstan is fine. However, she is just sitting doing nothing.
With the help from some list members, I worked on the motor and pressure roller. They both were too much lubricated, with thick oil, and was left for some time, so grease was hardened, and dust was all over the place. I cleaned it the best I could, using cotton ear sticks, 96º alcohol, and lubricating with a tiny drop of “fast” oil (sewing machine). I had the motor running on an external, 6V power supply for a couple of hours.
Be extra careful when dismantling the inner housing of the motor (held with three screws), make sure you mark the position, from 3 possible ones, one makes rotating direction good, another makes reverse rotation, another one cancels magnetic flux, and there is no rotation. See picture “Motor Disassembly 1”, where I am ready to start opening the inner housing.
Results follow. After cleaning, and properly re-lubricating, the deck is in great shape. Enjoy.