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For maximum signal reproduction and perfect tape interchangeability the ACE assembly must be consistent to a factory standard. To meet that standard the alignment tape is used to perform the ACE height and azimuth adjustment. The first adjustment uses an analog vacuum tube volt meter (VTVM) connected to the audio out phono connector of the Beta being tested. This is done to to monitor the monaural audio the Hi-Fi section should be turned off, if the machine has this feature. Often this simply involves selecting normal audio on a front panel switch, sometimes it requires shorting out or disabling the Hi-Fi circuitry. While playing the section of the tape with the 5kHz audio signal recorded on it, adjust the height of the ACE to obtain the maximum reading. This insures that the audio playback head of the ACE assembly is tracking the maximum amount of the signal path recorded on the reference tape. There would normally be a protection plate mounted to the top of the ACE assembly. It has been removed during these adjustments for convenience. Click on the picture. Now to insure that the ACE is perfectly perpendicular and able to reproduce the highest fidelity possible for the monaural playback the same measuring tools and method are used. But this time the azimuth screw is adjusted for maximum signal. The picture illustrates the method. Lastly comes the ACE location, click on the photo. To perform this adjustment slightly loosen the hold down screws for the ACE. This is so it can be move back and forth with a slight resistance. One of the screws is visible as a reflection in the inspection mirror. The special offset tool used forte adjustment is shown enlarged in the photo. The tool is place in the axial hole with the flange in the slot. Turning the tool slides the ACE back and forth. Click on the picture and notice how the ACE is to be moved. (The ACE protection plate is visible in this photo.) Examine the instrument setup in the upper right corner and notice that two images will be on the scope this time while using an external trigger. On the alignment tape there is a special tracking signal recorded for this adjustment that creates the pattern shown in the center graph and the scope photo at bottom left. This recorded signal has one half of the tracking signal removed (the B channel). This leaves a zero level gap in the recorded audio output waveform. This is going to be set the factory standard on the tape. With the tracking control knob at center and playing the tracking signal of the tape, the alignment tool is rotated to slide the ACE back and forth until the zero signal lines up with the missing B channel signal. Once accomplished the attaching screws are tightened to secure the adjustment. This makes the tracking center line up as closely as possible to the desired standard and produces better tape interchangeability with less tracking adjust when tapes are played from variable sources. This last part may seem complicated but in practice it is pretty straightforward and relatively easy to perform. The only difficulty is the care that must be taken to insure the adjustment remains as desired while tightening the securing screws. Click on the photo for an overview graphic of the path and components. Here everything is laid out in a linear fashion so the different locations and angles can be studied. Click once again to examine three tests and adjustments that finalize the servo speeds related to the drum motor, tracking center and video head RF switching. The tape alignment is done. The mechanics are done. Now to check it all again to see if everything looks good while playing a prerecorded test tape or an alignment copy. Once satisfied it is time to move on to the REGULAR AUDIO ALIGNMENT, click here   To go back to the previous page click here. |