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Now that we have corrected and proofed the power supply and clocks, we next move on to testing and adjusting the BSL servo motors. They are used for the capstan, video drum and reel motors, but only the first two are critical enough to require serious testing. (BSL is an acronym that stands for Brushless, Slotless, Induction and are the flat pancake motors you'll be seeing later on.) There are three photos layered beneath the one above. Let's discuss the one that comes next, so click on the picture. Here you see a Beta opened up and having the capstan DC bias test being performed using a scope. This is done while playing a color bar tape for each of the three speeds. The inset in the lower right corner shows a screen close up and a representation from the service manual. The tools shown enlarged in the lower left are used to make the adjustments. In the next photo (click on the picture) you see how the adjustments are made. Notice that if the variable resisters (called potentiometers or "pots") have plastic tops or covers, as in the photos on the left, then the metal variety tool can be used. But if they have metal areas exposed that would touch the tool, as in the two photos on the right, then the nonmetallic type adjuster is required. This is to prevent faulty values from being obtained due to the conductivity and capacitance of the human body. Click on the photo again and you will see screen shots and service manual representations showing several more common tests made to check the operation of the various servo motors. If we were to find any problem here the offending item would need to be corrected, repaired or replaced. (I know that the "L" in BSL doesn't match the "I" in induction but I didn't dream up the acronym.) Now before we move on to the actual mechanical operations involved in refurbishing there is one more check I like to perform, click here. To go back to the previous panel, click here. To close this panel and go back to the main page click here   |