MX-50 Meltdown

[Judas Jetski]

Hey.

I have this Otari MX-50, right? I'm using it for mixdown on my latest project. Everything was fine on it until today... well, everything wasn't fine, the thing made a hell of a clatter whenever I'd rewind and fast forward it. Today, while I was mixing to it, the tension arm on the takeup side started bobbing like crazy.

At first I thought the reel was warped, but on closer examination realized that the reel is straight and true. I stopped the deck and started turning the reel by hand. It does not make a complete rotation cleanly. It'll go part way, but then I can feel something grab. Something grind-y. Once it's rotated past this point, everything's fine again for another partial revolution. Then it's back to the grindy patch.

I'm thinking... motor bearing? Clutch? I think the brakes on this thing are felt strips, with a solenoid pull-on, so I kind of don't think it's the brake assembly. Ideas, anyone?

EDIT: In fact, I'm sure it's not the brakes, because I just found an envelope with a brake upgrade kit in it, and they are most certainly felt strips. Nothing there to grind... right? Or is there?

[nclayton]

The reel table height is adjustable on these. Are you sure even though the reel isn't warped that it might not be scraping against the head of a screw or something like that? It really sounds to me like you probably just need to adjust the reel table out from the machine a bit, but of course I guess it could be something worse....

Ned

[Judas Jetski]

Yeah, I'm sure it's not the reel. I forgot to mention that I pulled the reel off and tried turning the table by hand. It does the same thing. Smooth for about 225˚, then grindy for about 135˚. Then smooth again.

I've been thinking about it, and it can't possibly be a bearing. If it was a bearing, it'd be grindy all the time. Unless something awful has happened inside one of the motors and something has gone out of round (doubtful) it just can't be inside the motor.

I took a look at the exploded parts diagram in the manual, and there's nothing weird about this deck, mechanically. So my guess is it's gotta be something in the brake system. Excess wear, maybe, or catastrophic maladjustment. That's the only thing that looks like it could be a problem for part of a revolution but not all of it.

[@?,*???&?]

The tension arm is loose. The inner attachment screw or apparatus has dropped into the machine and is impeding the reel from making a complete 360 degrees. Take it apart.

[Judas Jetski]

Good call, Ned! As it turns out, there were a whole bunch of little things out of alignment on the supply-side motor. The deck did a face-plant at one time, before I owned it... one of the perils of ghetto-gear. I posted about it once before, with a different problem...

http://messageboard.tapeop.com/viewtopic.php?t=29344

Anyway, the reel table was far enough back that it was bottoming out on one of the screws that holds the fascia on, we think. Anyway, we just lined everything up better, and now it works OK. Big thanks to Rob at the Sound Source here in Rochester.