Video head replacement is a delicate operation that requires a steady hand. The small metal head chips are very fragile and even the smallest impact will destroy them. Therefor utmost care must be used when replacing a video disk. I wear surgical gloves to insure a better grip, and for cleanliness. In the illustration above the top section on the left shows the video drum in the VCR with the upper drum and disk removed. The hub in the center with the circular circuit board is the platform on which the disk is installed. Top right in the photo shows the new head disk in place before being secured in the holes with hex socket screws. The leads coming from the heads will be soldered to the circular printed circuit board. They supply the connection to a special radial coupling located beneath the mounting hub. This coupling provides a sympathetic path for electrical energy to travel back and forth. This unique configuration allows the head disk assembly to spin while still maintaining an electrical connection between the video heads and the machines electronics. (This unique coupling design will be shown later.) The lower left photo shows the installation completed. The chart at the right is a representation of how the video heads wear away over use and time. As you might suspect most of it occurs at the beginning of their life, then decreases as they wear away and begin to contact the tape with less and less pressure. Click on the picture for a disk replacement shown in more detail. This set of four photos shows removal of the components required to get gain access to the head disk assembly. This drum design is the most complicated because it has flying erase heads. Click again and the next set of four shows the removal of the disk and its replacement with adjustments being made using special gauges. The tools used during the procedure are shown in the lower left. (Note: the puller is only necessary for difficult removals.) Click to the next photo and examine the two couplers. These are act as transformers and the are spaced so they are almost touching. This arrangement allows electrical signal to pass between them. This is allows the disk to spin and still pass from one part to the other. Shown in the upper left is a video head removed from a disk. These head chips are aligned at the factory using a special fixture and a microscope. The selective shims are used under the head platform to achieve the correct trace or sweep. Screws located in the disk are then adjusted to bring the two heads into perfect axial alignment. The spacing must be exactly 180 degrees apart when striking in the same spot. On the right are the three types of video heads used for Sony Betamax. The top example has a single gap head. The middle is the dual azimuth type and at the bottom is a flying erase head. Click on the picture again and here are two heads damaged from impacts. Not a pretty sight at high magnification. The next photo shows the progressive wearing away of the video heads. The last photo is a close up of the two designs used in the Beta machines. The copper coils of wire are the main windings used for picture recording. The small green winding of the right head is for the special effects. The flying erase heads (not shown) are very similar to the one on the left. To go back to the window for VIDEO HEAD EVALUATION click here. To proceed to the next section on MAINTAINING TENSION AND TORQUE click here ©Misterßetamax go to homepage