HOW TO CHECK BEAM LANDING - COLOR PICTURE TUBES - PURITY CHECK

HOW TO CHECK BEAM LANDING - COLOR PICTURE TUBES - PURITY CHECK

CAUSES OF COLOR IMPURITY TO CRT TVs
Improper beam landing can cause color impurity.  Magnetization of the metal parts of the CRT, be external magnetic influence of extra loud speakers [might have placed very near to the side of the TV],  too can cause this.  If the impurity is due to magnetization, a degassing process can rectify this whereas, improper beam landing cannot.

With the aid of a Dot Scope, it is possible to view the beam landing at any given point.  There are 3 main points, which need to have correct beam landing in order to achieve good overall purity.

• Center area of CRT.
• Center Left of CRT.
• Center Right of CRT.

Note: When viewing images through a Dot Scope, the image is reversed due to the Optical nature of the lenses. IE. When you look through the scope and glance at the left side of the image, you are actually glancing at right side of the image. The following slides are as viewed through a Dot Scope.

DOT SCOPE SL-06

GOOD BEAM LANDING - NO ADJUSTMENTS NECESSARY: EXAMPLE:

BEAM MOVED TOO FAR RIGHT.  [ADJUST PURITY MAGNET]

BEAM MOVED TOO FAR LEFT [ADJUST PURITY MAGNET]

BEAM MOVED TOO FAR OUT [MOVE DEFLECTION YOKE BACK]

BEAM MOVED TOO FAR IN [MOVE DEFLECTION YOKE FORWARD]

BEAM MOVED TOO FAR LEFT - SEE HERE WHAT TO ADJUST?

MOVE THE BEAM RIGHT -- EQUAL ERROR [ADJUST PURITY MAGNET UNTIL BOTH SIDES HAVE AN EQUAL ERROR

BEAM MOVED TOO FAR OUT [MOVE DEFLECTION YOKE BACK]

GOOD BEAM LANDING [ADJUSTMENT COMPLETED]