Common troubleshooting of the hottest Philips bald

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Common troubleshooting of Philips slick heads

Philips slick heads are widely used in various VCD machines. With the extension of the service time of VCD machines, different degrees of failure will occur. The author summarizes the experience and skills of maintaining Philips bald heads in recent years, and is willing to communicate and improve with the majority of maintenance personnel

The basic requirement for the compact style is that the two supporting end faces should be parallel to each other.

the damage of the optical head can be basically classified as the aging of the laser tube, the obstruction of the optical channel caused by the dirt in the optical head, the abrasion of the objective lens, the damage of the focusing and tracking coils, etc. the location and degree of the damage are different, and the fault phenomena are also different. Here are a few examples for analysis and summary

for example, the coyote VCD machine does not read the disc, and can read the catalogue after a slightly longer power on time. It is also recommended that the most suitable reliable products for consumers, and it can be played normally after taking time (such as taking photos) to refer to relevant technical materials

according to the phenomenon that it can work normally after a little longer power on time, it is analyzed that the root cause of the fault is related to temperature and voltage. The voltage of each group is normal after startup and does not change with the length of startup time, thus eliminating the factor of unstable power supply. According to the previous experience of machine repair in order to meet these market needs, it is judged that the aging of the bald head causes no disk reading. If the conventional repair method is followed, the fault can be eliminated after replacing the bald head. However, after long-term maintenance practice, the author found that the aging failure of the optical head can be solved without replacing the whole optical head component, that is, replacing the Philips laser tube and restoring the optical head to normal use. Because the new laser tube is replaced, the service life of the repaired optical head is basically the same as that of the new optical head, but because the quality of the new laser tube is slightly different, the service life is not completely the same. The specific replacement methods and key points are as follows

first of all, remove the original laser tube correctly, which is the key first step for success. If the removed optical head positioning glue shifts, the new tube on the replacement will not read the disc. The correct method is to bend the tip of the tweezers into the shape of an integrated circuit extractor, clip it in from both sides of the fixed plate of the bald head, and pull it with a little force, and the Philips laser tube will come out. Then clamp the two sides of the laser tube with the above deformed special tweezers, and heat the 10 feet of the laser tube with a soldering iron at the same time (which can be heated in turn), because it is to dismantle the tube, there is no need to worry about the tube being damaged by static electricity. After removing the tube, insert the pin hole with a steel needle or injection needle to facilitate pin insertion. It should be noted that the curing adhesive beside the tube cannot be removed, and it should be left on the circuit board, which plays an important role in the positioning of the tube and the alignment of the optical target, and saves a lot of adjustment time

next, install a new laser tube. First, pay attention to the model of the light tube. Generally speaking, Philips 1201 and other commonly used laser tubes start with 30p. If you can't find a laser tube of the same model, you can use a tube beginning with 30p instead, and you don't have to worry about the different spectrum or other parameters. It is best to wrap the tube surface with a good white paper when putting on the tube, and then weld it after pulling out the soldering iron plug. Because the laser tube is installed, in addition to anti-static, attention should also be paid to the positioning of the tube, which is required to be consistent with the position of the old laser tube, such as diagonal welding and other steps to achieve the positioning requirements of the new tube. After welding, the machine can be tested under the condition that other parts of the bald head are normal. Within a few seconds of searching the disc with the optical head, measure the voltage at both ends of the chip capacitor next to the laser tube, which should not be greater than 1.9V; If it is greater than 1.9V, the bald head will age faster; If it is lower than 1.6V, the laser tube cannot work, which also indicates that there is a problem with the quality of the new laser tube. In practice, the author found that most tubes can work normally under 1.9V, and the working time is as long as several years

the above is the author's experience in replacing Philips laser tubes. The effect is satisfactory in practice. Hundreds of bald heads have been repaired by this method

some bald heads are caused by damage to other parts and do not read the disk. For example, a Wanlida n28 machine is observed to grind the objective lens without reading the disc. The optical head is moved to the outer end by the method of external power supply. After slightly heating with a hair dryer, press the objective lens with tweezers, pry the objective lens open with a small flat knife, and then replace the objective lens of the same model, stick it with 502 glue, that is, the final amount of plastic may be increased, and it will work normally. Since the installation position of the objective lens is marked with corresponding marks, the troubleshooting of this case is relatively simple

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