bipolar capacitors
The denunciation of this Macroview mp712s 17 "monitor was no power. Once the cover is removed and the power, you could hear a soft" chip-chip " sound that indicates the power trying to get out, but something had caused them to close. The LED does not light at all. Just as the solution to the problems of another monitor, the first thing I do is look for any burn mark, loose connection in the wires, burnt components and joints dry. It is true that there was a marked burned clear in the center of the main board.
Very inspection revealed that it was a FET with the number of IRF630 (n-channel FET) and is located in the s-correction circuit. As for the FET behind the main board has shown that 3 has a cut dry joints. I think this is the reason why the burnt fet. Normally, when you found a component that was common in dry, chances are you may have dry joints in another area. Scanning through the Board noted a large number of joints dry in the circuit and the most obvious was the secondary side of the area just after switching mode power transformer.
Checking the capacitor internal flyback, horizontal output transistor (HOT), and burned about fet components could not find any possible components so bad after renovation fet monitor turns on. However, the monitor would turn on but without the high voltage and could smell something burning in the area B + circuit. Monitor was quickly turned off and unplugged from the AC connector. I use my finger to tap the B + fet heatsink was very hot and not normal. Because of this, I suspect the B + FET, have also developed a short circuit. Having established that, yes, the B + fet had gone too bad. The B + FET is IRF634A number and even a new replacement monitor was still refusing to take lines.
The only option I have right now is to test voltage or measuring food. Place the black meter probe of the cold and the red probe to B + flyback point of the needle and power over, there was no tension present in the PIN. This indicates that the B + circuit is working and that the fault could be elsewhere. Since the flyback transformer internal capacitor and primary winding double check the circuit only suspected would be in the driver's side horizontal.
Before using the oscilloscope to check the present of the waveform at the base of the hot, choose to measure the supply voltage to the horizontal driver transformer. Placement red probe to the power line as shown in the photo and the black probe to the cold ground with the ignition, I noticed that there was some unusual reading recorded on the meter. It was not until about 4 to 5 volts (where it is assumed that at least 12 volts) and pulse (meter pointer moving up and down). This is the idea that we seeking. From here we can take our time to concentrate on finding the true cause.
Using underground X1 ohm analogous to where the probe went black on the line supply and the red probe to the cold, do not show a low reading ohms, but in this case, the pointer goes high (low ohm reading). They should not be shorted components which causes the meter reading showed a short circuit. Follow along the supply line to the horizontal driver transformer components found around a short circuit horizontal driver transistor Q401, with a number of 2N7000. Normally, instructors, engineers prefer to use a bipolar transistor, horizontal driver transistor compared FET. A new FET completed the repair of this Macroview mp712s 17 "monitor.
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Article Source: ArticlesBase.com – How To Repair Macroview Mp712s 17″ CRT Monitor
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