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Old 16th November 2011, 11:56 PM   #11
Sorscha is offline Sorscha  Netherlands
diyAudio Member
Join Date: May 2009
Location: Hoofddorp
Maybe somewhat late ... sorry for that.
The motor holds two "see thru" fixed rubber bands (these are at the ends of the motor) and it holds two belts. A long one that drives the capstan wheel, and a short one to drive the ... dunno just now (it's late here).
For both wind and rewind functions you don't need the belts on the machine.
Put it upside down and flip the main pcb upwards. Look at the motor when you push either wind or rewind. You'll notice that the motor tilts to either (wind / rewind) direction. So, the rubber bands are driving the reel hubs for the wind / rewind functions. It is this motor tilting that should be examined.
Be very careful with those rubber bands. Select either wind or rewind and check which way the motor tilts. This will engage the function to the reel hub.
It is not very uncommon that it just slips. Get a clean cotton cloth and clean both reel hub drums and the rubber bands (use just the cloth). Inspect again,
You can push on the other end of the motor to check the force on the reel hub drum. It should spring back into (onto) the selected postion (the reel hub drum)
Put the machine on its backside. (remove the lid please). Rotate the reel drum which you have selected for function (wind is the right reel hub, rewind is the left one). It should rotate with friction. If you look at the motor you will see it rotate when you turn the reel hub. Now hold the motor and turn the reel drum.
Does that goes smooth ? ... bad. It goes with reasonable friction ? ok. The same for the other function as you can easily see it now when you have done this.

Reel hubs:
Perform the following: Machine face up (normal use). No power to the machine (no batteries also). No reels mounted. Put it into play mode. There is a little roller just left from the tape heads block. Push it inwards all the way (towards the heads block) and hold it there. Rotate the left reel hub, it should rotate freely.
The operation for the right reel hub is a little different since this is a "fixed" tension mechanism. This reel hub never rotates completely free. It is difficult to adjust this to the right torque. My advice is to leave it when it "feels" like this:
Machine with power on and in play mode. Fit an empty reel to the right (take-up) reel hub. Push the play button and the empty reel with start rotating. Stop the reel with your loose finger on the outer edge. (The tape tension is roughly 60 grams for the take-up reel, measured from the reel core). Start rotating against the motion with your finger. This should go very smooth. If you give it a gentle extra "swing" it will do this about a second before rotating the other way.

One other (and last thing) that could be is that the motor itself doesn't run freely, which is easy to check. Remove the two belts from the motor. Give it a feel on one of the rubber bands by rotating it. You can feel the magnetic force.
Remove all the hairs if they are on the motor axle) It should feel like a normal medium power electromotor. If it feels and runs "stiff" ... it needs lubrication. But it is a pain to get that done correct if you want it for every day use. If not, a tiny drop of sintered bearing oil on both motor ends will (most of the time) do the job. I don't use exotic lubricants and they can be bought in the better machinery stores.

Replace them with new ones please. The motor belt (the mid longest one) should have a little "elastic" left when mounted. If you grip the belt between two fingers and move it, even quite firmly, it should never slip on either the flywheel or motor. If it does you will hear it in your recordings and playback

Cheers !

Last edited by Sorscha; 17th November 2011 at 12:16 AM.
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