Otari 8-track tach roller

  • Thread starter Thread starter ofajen
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ofajen

Daddy-O Daddy-O Baby
Might be getting to that time... I've been noticing that the tape timer on my Otari MX-5050 MKIII 8-track doesn't register properly in reverse wind. It does fine in the forward direction, whether in play or fast wind but slips about 3% in reverse. I can make it better temporarily by swabbing the tach roller with rubber cleaner conditioner, but it probably is about time for a new one.

So, has anyone replaced one? The manual doesn't spell out how it's done, but from the parts diagram, it seems to be held on from underneath the deck plate by a big, circumferential washer and nut, so I'm assuming I'll have to open it up from underneath and take those parts off to remove it.

Cheers,

Otto
 
Sorry, I haven't. If I remember right on my MTR-10 I have to get it from the bottom. Again, I'm really not sure of that even on mine. I know that isn't a big help.
 
Otto, preliminary study of the exploded view leaves me a bit muddled...I know the tach roller assembly on my 58 looked very similar and there was a single scew accessed from the back of the transport plate to remove the assembly, and of course there were a number of things that needed removed before being able to access that.

I know that probably doesn't help...
 
Does it look like this?
You could get some 400 grit sandpaper and very carefully and evenly resurface the roller..
Just roll it a few times across the sandpaper with medium pressure on the roller..
You could also increase the back tension on the take up motor...
 

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Mike Keith said:
Does it look like this?
You could get some 400 grit sandpaper and very carefully and evenly resurface the roller..
Just roll it a few times across the sandpaper with medium pressure on the roller..
You could also increase the back tension on the take up motor...
Click to expand...

Yes, it's that part. I figured I might get to that point before buying a replacement, but I'm budgeting for it over the next few months. That was a standard field technique for taking the shine off of capstans, though I think the recommended technique is to gently slide the sandpaper parallel to the axis of the roller and along the surface.

Cheers,

Otto
 
Mike Keith said:
You could get some 400 grit sandpaper and very carefully and evenly resurface the roller..
Just roll it a few times across the sandpaper with medium pressure on the roller..
Click to expand...

My belated thanks for the tip! A quick update: I got some fine sandpaper and scuffed the surface of the tach roller today and now it tracks rewind perfectly again. I used very light pressure, rubbing across the surface from the bottom edge to the top edge of the roller (parallel to the axis of rotation) and just slowly rotating the roller around to work on a new area until I went all the way around a couple of times. That is similar to the technique recommended by Ampex for roughening up the surface of a shiny capstan. Sure beats having to buy a new roller and pull the machine apart to replace it (or pulling the machine apart and leaving it out of service while I wait to have the roller rebuilt)! I hope I can defer that job for a while!

Cheers,

Otto
 
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