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Focus Adjustment

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Tip from Louis Carliner:  "My focus procedures for the Toshiba RPTV's have evolved and been refined over the past several years.

  1. There is no substitute for the helper and the biggest mirror you can find. The use of a camcorder and 13" monitor has been found to be unsatisfactory in that the camcorder autofocus results in very misleading results.
  2. Use of lens covers and the user picture quality adjustment as focus material has been found to be the most satisfactory of the sources. The internal convergence grid pattern is simply too defocused to be satisfactory.
  3. The use of tracing paper does not work in that the likelihood of reproducing the identical focal plane is low.
  4. I strongly concur with r and r'ing the lens assembly so that the wingnut is in the rear. Just make sure that the same precautions that are used with reinstalling an engine head is used so that the retighening process is even and that the screws are not retightened excessively.
  5. For removing the "glare screen", I find that simply relocating it to the rear is not fully satisfactory in that I have less ability to cure any possible lenticular sag. The best procedure is to get yourself a supply of 1/8 by 3/8 inch balsa or basewood strips from Michaels or Lone Star Hobby Wood, paint the strips on three sides with spray dull black paint, then glue it to the surfaces of the clamps that face the screen assembly when the clamps are reinstalled. Use the non-painted wide flat surface for the gluing surface. The equivalent of Duco cement or epoxy will work best on especially the 56 and 65 inche models. Super Glue or Crazy Glue or the like do not work properly. All of the clamping surfaces need the wood strip build out. You will want to use premium grade masking of 3M blue painters tape for clamping the strips to the clamping surfaces until the glue has set. Once the strips have been glued and everthing is solid, the best method for preventing "lenticular sag" is the follows: After the overscreen has been freed from the sandwich and removed, use some magazine stacks to raise the sandwich above the front frame reveal.  The viewed side will be facing down, and propped up by the six set of magazine stacks of identical thickness. Then start tighening down the screws, starting from the top center. Be sure to have the remaining clamps screwed in, but loosely. Now stand the screen frame up, but with the bottom portion resting on book stacks to keep the fastening cleats free. This is very important. Then start tightening the remainder, starting from the top sides and working down and ending in the bottom center. The idea is to hang out, aka wallpaper any sags. You can tap the screen surface gently to verify the absense or presence of sag. When done, make sure that all handling is done by the sides! It is important the screen is not racked as it is handled.  
  6. Using the lens covers (Duvetyne cloth circles work very well!). Cover the red and blue lens, darken the room, put up the user picture quality adjustment screen and work the green lens barrel. Of course, you will have your helper ready with the mirror! Then go to the front and work the green focus pot.
  7. For the TW56/56X82 models, the CPC magnet adjustments need to be checked, and adjusted as necessary. Using Title 17, chapter 14 or 15 (preferably), put up the dot pattern. Not all of the dots are consistently round. You may wish to use an internal dot pattern generator as an alternative. What you will do is to electrically defocus on the left of center and right of center and not if the most intense portion of the blob is in the center and whether to shape defocuses EVENLY or becomes eliptical in opposite directions. If so, then the magnets need to be adjusted. The service manual procedure for adjusting these is good. Rather than repeat these, follow these, except I found the VE dot pattern more satisfactory than the internal pattern built in and as described in the service manual.

    Caution: The magnets have been set with paint or silicone goop! These need to be carefully freed up so as to not crack or break the magnetic rings, especially the centering ones! Use a pair of needle nose pliers and single edge blade to remove the goop and to break the paint seal.
  8. Repeat steps 6 and 7 for the red and blue tubes. In the case of the blue tube checking the electrical focus first may be in order.

Don't forget to have the picture level down below any point of blooming first. With the above procedure, near computer monitor "crispness" on the X80/X81 models or later is readily doable.