Eye Pattern

Dust is enemy number one of the lenses lens cleaning. A dirty optical lens can cause a myriad of failures: since jumping on the tracks, up to the inability to read.Dust, moisture, cigarette smoke and others, adhere on the surface of the lens. It is recommended to clean manually, preferably with products for cleaning lenses of cameras (or isopropyl alcohol) and sticks with cotton (swabs), according to the manufacturers specifications. You can follow the recommendations given in Figure 2, but do not use chemicals such as gasoline, acetone or THINNER. Many of the current lenses are not made of glass, but plastic, so the use of harsh chemicals melt them or stain them permanently. Sometimes, a dry cotton swab does very good job. Indeed, it should be noted that sometimes customers use a commonly available cleaning CD. As most of these discs only bring a small brush that sweeps the surface of the lens, it is common that not really cleaned the dirt layer.

So it is preferable to manual cleaning. Signals after carrying out the above process, check the signs. The first signal we are going to observe with the oscilloscope, is the RF (radio frequency or Eye Pattern). Most computers have a test point marked on the Servo card with the letters RF. To connect the oscilloscope, we must have a signal such as that shown in Figure 3 while the disc is playing. If we have a team which seems that it is reading, but does not transmit audio, we must investigate this signal. If this signal is present, it is an indicator that the optical reader and RF amplification section are working correctly; the problem is in another section.The signal should appear so clear as in the photograph, and must be clearly distinguished the diamond shape for the entire signal. If you already cleaned the optical lens and did not get a good result, it is suggested an adjustment to improve the quality of playback of the disc.There is usually a potentiometer with the letters RF, although it may be that on some models say PD Balance or Best-Eye Adjustment.

Adjust the signal until you see more great of possible, and to minimize its vertical fluctuation; in other words, that you jump the least that can be. If I had to replace the lens, it would have to take into consideration the type of servo drive system. Why? I will explain briefly. On computers that have ten years or more on the market, the servo system is virtually analogous; It would have to do six manual settings to make the appliance operate correctly (Figure 4). But with the development of technology, these systems have been replaced by digital circuits (Figure 5). In fact, on some models only a control is adjusted, and the other signals are self-adjusting by means of a signal sampling (or feedback) that takes the microcontroller; other models conform completely by themselves. I hope that these tips will be useful in the Bank’s service. see you soon!

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