Fifty-one inch and smaller sizes require the screen to be mounted in its normal position. In these units, the servicer must reach behind the screen to make mechanical focus adjustments. When doing this, the screen must remain against the front of the cabinet to maintain proper focal length while making the adjustment. If it becomes necessary or more convenient when servicing the smaller screens, the lenses can be detached, rotated 180 degrees, and remounted so that the wing nut adjustments face the rear of the unit. To turn the lenses around, remove the 4 screws in the lens mounting tabs (Figure 29). (Take care not to loosen the hex head bolts with springs. These hold the lens to the face of the CRT and fluid leakage will occur if they are loosened) Rotate the lens 180 degrees and replace the screws in the mounting tabs. Remove the light shield by removing one screw from the center (Figure 30). With the light shield removed, the mechanical focus adjustments can be made from the rear. Observe the backside of the screen as the lenses are adjusted to attain proper focus.
