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Regular audio for the Betamax is done just like with reel-to-reel recorders, It is linear and later called the normal audio by Sony after Betahi-fi came along. Click on the picture and here are the some adjustments being made with several type of tools to several design of parts. More tools are shown on the right. These are non-conductive because the human body conducts, stores static electricity, offers resistance and can act as a capacitor. Using tools that don't conduct isolates those demons from the test results, an important factor when dealing with very low voltages and small signals. Click on the photo and in the upper left you see where the audio head is located in the ACE assembly. The type of recording done by this head is the same as with common audio recording. It is used for both playback and record. The components for reproducing and recording the regular audio signal are usually contained in a metal shield or can (see upper right in the photo). This is to reduce interference from stray motor signals when the VCR is in operation. Not many adjustments are needed to keep this section operating up to standard and the process hasn't changed much since Beta was first introduced. Over time some processes have become concentrated into various integrated circuits to save space, money and to promote simplicity. Shown on the lower left is the underside of an audio section showing the traces, the can cover is removed. To the right is the same section from above with the top removed to show the inside. It has a bias current adjustment set the signal that cleans and prepares the tape as a magnetic signal being recorded onto the tape. Levels for record and playback can be adjusted in the example shown, in some models they are not. Some units have equalizer adjustments so the playback can be modified to compensate for the different characteristics of the sound and speed for  ,  and  . In this unit this is handled within an IC. Before I show some general adjustments for regular audio now would be a good time for me to emphasize again that all of the discussion in these overviews on refurbishing a Beta are of a general nature and not intended to be a lesson on how to work on Beta. I am covering many types of designs, styles and models indiscriminately with the intention of giving the reader an understanding of the overall operation, adjustment and refurbishing of the Beta system. Hopefully is as entertaining as it is informative. Click on the photo. This page from the service manual shows the test equipment and fifteen steps to aligning the audio. This information includes the Betahi-fi section that is not covered here. It is purposely going to be left out of this normal audio discussion. Items ten and twelve thru fifteen apply only to Betahi-fi. I'm not going to go into a lot of detail here, read thru the different checks and tests, it's fairly straightforward. Normal audio doesn't give a lot of trouble and seldom needs adjustment unless a component gets replaced. One other note, the SL-HF900 being tested here is Betahi-fi and therefor left and right channels are checked separately and together for monaural audio output, something not done in non-stereo units. Click through the rest of the pages, there are two more. Notice that item eight continues on the next page. Also note that a scope is mentioned several times throughout the testing. The graphs are representations of how the scope waveforms patterns would appear on the screen. To proceed to the next section that describes some CORRECTIONS AND IMPROVEMENTS click here  To open the other subjects discussed in this section: ©Misterßetamax go to homepage |
