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Analysis and maintenance: according to the phenomenon of failure, the author initially determined that the failure caused by the bald head. Therefore, in early repair of multiple type 2368 VCD machine by changing the new Sanyo SFP101N laser head component approach processing, of course, VCD machine soon returned to normal. Later several users asked to use the time is not long, why the laser head so easy to damage? The tests were carried out on several aspects of the problem, and peer discussion, finally found the answer, the process is as follows: This machine is the integration of decompression plate, drive, servo movement decoding, encoding are concentrated in a small circuit board, the circuit model in Taiwan Winbond block MM1469 (four channel servo) (W8861IP, RF, W88631F (amplified) DSP and servo control), W992250QF (decode), W9952QP (video encoding), W99132P (control system) a set of digital integrated circuit, integrated circuit board has high stability, high load, but did not reduce. The power supply uses ordinary simple rectifier voltage regulator output 5V and 8V voltage (as shown in figure). Monitoring voltage in the stop state is actually only 4.8V and 7.8V. In the boot of the initial state, search tracing touch drive block MM1469, feel the heat quickly, that current is large, but with a million in drive block is basic and normal, and increase the heat sink, temperature Shenglve decreased but read dish remains difficult.YQ9service manual download site
The observation of laser intensity is appropriate, unlike laser head aging, temporary maintenance into a difficult situation. After the thought of "electronic newspaper" has been introduced on the low power supply voltage caused by the reading of a hard disk maintenance example, immediately inspired ideas, decided to try to solve the power supply.
First, the input terminal of the 5V and 8V voltage regulators are respectively connected with 3300 F, 2200 F filter capacitor (see figure on the dotted line), the output voltage is relatively high. Then start playing, can read, tracing and shorten the search time, paying off test. In order to further improve the state of power supply, reduce the internal resistance of the power supply, to reduce the pressure drop, the power supply circuit for the simple change: C1 from 2200 Mu f changed to 4700 muon f; C2 220 Mu f changed to 470 Mu f; C3 2200 Mu f changed to 3300 G f; C4 220 Mu f changed to 470 F, pressure value remains unchanged. The voltage regulator IC1 and IC2 are respectively connected in parallel with the same type of block, each pin corresponding to the welding and welding; in order to heat up, and then clip on a small piece of alloy aluminum heat sink.
In the power supply changes after the power test machine, the problem of the difficulty of reading a complete exclusion of a variety of optical discs are able to play the normal, the image quality is also relatively high.
From now on the author in the repair of the model does not read the disc, the first not to replace the bald, first to improve power, often increase the number of components of the failure to eliminate. It is much lower than the cost to buy a shaved head, the user is satisfied, the maintenance is also simple and easy.
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