ENTRANCE SIDE ADJUSTMENT
The illustration shows the preparation for the entrance side adjustment. Whenever this is performed the exit side must also be adjusted. If you'll look at the illustration above you will see the preliminary steps and the tools used. First the number six guide is raised slightly to allow the tape to move up and down as it enters the video drum (when the number five guide is later raised or lowered). The number four guide is lowered all the way down so it also will not restrict interfere with this movement. Finally the number five guide slotted collar is loosened so the locking screw can be backed out, this allows the collar to turn which lowers and raises the guide (roller). With the scope still set up and while playing the tracking section do the following. Insert the test cassette, press play and set the tracking control to about 60% of maximum to reduce the amplitude of the waveform. Turn the number five guide until the start of the waveform generated on the scope sticks up slightly above the peak waveform line, as shown above lower left. Now lightly tighten the locking screw to secure this adjustment. Next lower the number six guide until the waveform becomes flat. If the waveform successfully flattens with cotton cue tip between guides four and five gently press down slightly up and down on the top edge of the tape. The waveform should flatten, distort slightly and then return to the 5% to 8% over peak. If these conditions are met slightly loosen the set screw and raise the number five guide collar to flatten the waveform. Tighten the set screw to secure the collar. The number six guide is now lowered to produce a slight curl in the tape then raised until it flattens. Next the number four guide is raised to just produce a small distortion between it and the number five guide, then lowered until it just goes away. Ah... it sounds so easy. The screen shots on the right are as follows: top is entrance side doesn't flatten even when reduced to 60% of maximum, middle is guide to low or high, bottom is the desirable flat waveform. Click on the photo and see how the number five guide effects the travel of the tape over the drum Next the number two and three guides that come before the shuttle are adjusted. But there is something else that seldom is needed. It is done if the conditions cannot be met and the waveform will not return back to slightly over peak when tested. These adjustments are covered in the next step, click here. To go back to the TAPE PATH ALIGNMENT AND ELECTRICAL ADJUSTMENT click here.

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