THE PINCH ROLLER
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The pinch roller is pressed against the capstan shaft during play, reverse, scan and record. It is made using a very resilient rubber but it can get hard and begin to crack from age and use. But the biggest issue with this rubber is it picks up the graphite and oxide that comes off of the video tape. This can harden the rubber and make it slick. This causes it to slip which generates uniformity problems like tape wander and speed errors. In the photo above it is easy to see the difference between the rubber of the new one on the left and one on the right. If the rubber is still soft and it only has tape deposits built up it can usually be renewed by cleaning it with a special solvent. This rejuvenates the surface. The assembly has a small caged bearing inside and sometimes it will fail, causing the picture to shake in an erratic manner. The bearing can be tested by rolling assembly across a hard flat surface. If it is bad it will chatter or run rough. Click on the picture above and you will see that small bearing in the exploded photo in the upper left. The dime is to give you a size perspective. Here the pinch roller assembly is shown mounted on its geared slider. The toothed crescent is what moves it in and out of position when it is driven by the threading motor transmission. It is positioned under pressure against a wedging block by the tension spring. Notice also that the slider assembly has the number nine guide (a roller) mounted on it just right of pinch assembly. It is very similar to the number five guide on the shuttle block. It has the job of drawing the tape out of the cassette during the loading procedure. It also guides the tape back into the cassette during forward movement. When not in the loaded position the slider and roller sits parked next to the shuttle assembly inside the cassette pocket. After a cassette is inserted, and the electronics knows that it is down and properly seated, the assembly travels out of the triangular pocket and pulls the tape out along with it. To better picture this, click here. The number nine guide can become worn internally but normally doesn't need replacement. It is adjusted during the tape path alignment because it can affect reverse play, stepping and scanning   Next we take a look at the LOADER AND REELS, to do that click here To go to the other subjects covered in this TAPE HANDLING COMPONENTS section:
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