Nak RX-505 adjustment question

[perryinva]

What would the adjustment be that determines the force required to trip the autoreverse switch? One of my RX-505s will autoreverse prematurely on certain tapes that work fine on the other 505 and on my other dual capstan deck, the Yamaha K-1020. The tapes in question don't FEEL like they have any increased friction, but they (maybe 5 or 6, all but one, pre-recorded, BTW) do the same thing at about the same point in the tape, and always near the end (within 3 minutes or so of the end), but obviously still on the recorded tape area. If I turn off the autoreverse switch, then the tapes will simply stop at the same point. I have the Service Manual and have done quite a bit of work on my decks, so I am familair with the mechanisms. Thanks.

 

[perryinva]

Bump...Anybody?... Anybody?... Beuller?

 

[maitai]

I have no idea.

But I DO have a pdf copy of a 505 service manual! I guess the info should be there.

Give me some means (email attachment?) of sending it to you and it's yours.

 

[Jon_Logan]

The auto reverse is not triggered by sensing force. It is triggered by motion or the lack thereof. Sorry for my foggie-ness regarding the RX-505. it is the Nakamichi DRT (Diffused Resonance Transport). ....Nak built. The thing to try to catch it doing is see if it stops 'taking up' tape. If it does stop taking up tape that will trigger a auto reverse. You might want to take off the tape carousel's clear plastic window, put it in play without a tape and see if the take up reel has decent torque. by hand is good enough. If torque is there, you want to see if a belt is coming off the take up reel table and make sure that the belt moves. If there is no belt on the take up reel, you might want to bring it in for service, as it indicates that an opto- sensor has gone fruity.

 

[Nakdoc]

Perry,
It uses optical sensors beneath the reel tables. There are two. Does it reverse prematurely going both directions? Each sensor goes to a different micro, and there doesn't appear to be a timing circuit that could have changed. If you are a smoker, you might remoce each reel table and clean the silver/black pattern. I suppose one or both sensors could be noisy?
A second possibility is the reel motor drive torque is a bit low.

 

[perryinva]

That's what I needed to know!! I have the Service Manual..Thanks, tho!! May need a new reel tyre, then, if it's torque...(I have them, just know it's a REAL PITA to change!!!). Now at least I know what to look for!