Konka HD color TV P2902T burning tube I repair method - android - Phones Developers

Probe current voltage pin 420*4450 head diameter 5.0 over current current and voltage pin
Electronic scale crystal oscillator 3.2*2.5mm 3225 16M (16.000MHZ) 12PF 10PPM 20PPM 30PPM
Photocoupler

A Konka P2902T HD color TV can't be turned on twice.
Check +B voltage 140V normal, the test line pushes the upper end of V401 BSN304, the line pushes the transformer primary 140V, does not change when the second boot. Prove that the line did not work, check that V401 BSN304 is broken, and then turn it on again after the replacement, the line current is normal but the tube burns out after a few seconds.
It seems that the problem is not small, put on a new line of management, because it can still be turned on for a few seconds, so use these few seconds to measure the working status of the line as follows:
1. The field voltage +-15V is only +-6V.
2, 200V is only about 150V.
3. The same is true for the reverse process capacitor.
4, the proxy deflection has not improved. Suspected that the high voltage package is broken, bought and replaced, or the same. I really can't think of anything bad.
Let’s go back and look at the promotion. How do you prove that the promotion is good or bad? After reading the online experience, most of them are repair welding. In fact, I have already repaired the welding.
In order to prove the quality of the promotion, based on years of maintenance experience, only the driver on the line to find the answer. First, prevent the burning of the pipe, disconnect the line power supply resistor R427, maintain the power supply driven by the line, and disconnect the line to push the secondary line of the transformer to the base of the line. Use the multimeter to exchange 10V files, start the measurement line to push the secondary AC voltage of the transformer, and the high-definition machine is 3.8V and stable (it has been verified on this machine after repair).
This machine pushed the AC voltage of the transformer secondary to 3V and changed. The 3.8V 0.3A bulb was used to push the secondary of the transformer, and it was obvious that there was a bright and dark change. This is the reason for burning the tube.
Check and push, each component is normal. The problem should be a push signal. The line push signal HD of this machine comes from the scanning and video processing board, the board number is 35004571, and the crystal oscillator is 29.49. This board is a sesame component. Repair is a bit difficult. I had to buy one and put it into normal.
In order to find out the root cause of the problem, I decided to install the boss. Disconnect the line supply resistor R427, keep the line-driven power supply, disconnect the line to push the transformer secondary to the base line of the line, and connect the 3.8V 0.3A bulb to the secondary of the transformer. Using the method of stalking, I ended up finding out where the problem lies. It turns out that the HD signal of the N301 12-pin is driven by the V301. Due to the leakage of the V301 CE pole, repeated burning tubes are caused. Replace the V301 of the patch with the ordinary 1815, and test the 3.8V 0.3A bulb to emit light normally. Restore the line circuit and start working normally.
Things have been repaired and left a fortune. A high voltage package and a scanning and viewing processing board.
Finally, I told everyone that the high-voltage ignition of this machine caused damage to V301 and V401. When the V401 was found to be bad and replaced, the problem of V301 was not found. The startup also formed the problem of repeated burning tubes. Find out the problem of V301, it is repaired, it is as simple as that. In the future, I will encounter a high-definition machine. I can't start the second-time or repeated burning of the tube. I will start with the inspection and start with the "disconnected power supply resistor R427, keep the line-driven power supply, and disconnect the line to push the transformer to the secondary level." The connection, using a 3.8V 0.3A bulb to drive the secondary of the transformer, may save an expense. But do you have any good methods to teach me, let me also learn. (to be tested on other machines)
P2908T.pdf - Foxit Reader 2.0 - [P2908T.jpg
Konka modified p2902t drawings 7.pdf - Foxit Reader 2.0 - [Kanga p2902t drawings 7.jpg
Modified P2902T.pdf - Foxit Reader 2.0 - [P2902T.jpg

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