The repair of the television was not done by changing the board, the power supply was completely paralysed and the flight line welded to 0. 1 mm screens。
I've broken three dimensions, two black screens, a flower vertical line. Not once did it follow the video tutorial。
The internet says that one day i learned to fix tv, i bought tools, welds, hot-wind guns, a watch, and a fast-start book, and i went to the used platform to get a 8k86 scrap machine. Take a look at the small plastics, which are so dense, they can't even see. Electrometric voltage, 5vsb, 12v, but green light is not on. Turning the forum, someone said to change the face, so i changed c305, the green light went on, and it went out in three seconds. Change c93 or go. In the end, the oscilloscope was used to catch the primary chip on the switch without a repositioning signal and to track it to a solid-pressed diode welding welding -- two seconds with a branded iron, the light was on, and it went into the system。
It turns out that “with voltage” is not the same thing as “with voltage”. If the tracer is more than 150 mv, the tcon chip strikes. I used to tell you, the numbers were steady, and i thought it was okay. Then he borrowed a friend's oscillator, a dozen waves, strangulations, like an electrocardiogram. It wasn't a broken watch, i wouldn't look。
Backlights are worse. There's a l32c12, and the led bead goes off in a flash, and i thought the light was broken, and i took all three of them for a new one or a flash. Finally, it was a patched c305 short circuit in the back of the circuit, which was short, a constant chip thought the light was blown and locked directly into the output. Switch it off, the lights will hold. But it's only two millimeters long, and it's got a smaller mark than ant's leg, and it's hard to use a watch bell。
It's the most grinding of the screen. The osd menu is normal. The images are all vertical. Change the signal line first, it's useless; wipe the gold fingers of the interface or the vertical line; change the main plate or the vertical line. Finally, the logic board was removed, the gamma voltage was measured, the foot of von 3. 2v, the foot of vofff 1. 8v was measured, but the voltage was fully floated at several points in the middle, with high and low, and it was drunk. According to the information, it was a welding of the cfo chip, but the cfo was a black piece attached to the screen, with no ability to touch its fingers. I took the hot wind gun to 280 degrees, blew it for eight seconds and the screen didn't work. 10 more seconds, smoke on the screen, stop. The teacher was then asked to take advantage of the infrared heat imager and found out that the cof had a point in the lower left corner that was still 5°c lower than elsewhere before it could fly there. The copper wire is 0. 08 mm, the welding table is 300 degrees, the hand is shaking and it's filamentated. Welded four times, powered the third time, and the vertical line was gone。
The flying line is not a chain of copper wire. The line will be pushed into the metal line at 0. 3 mm deep on the screen, too shallow, too deep to break the insulation layer, and directly short circuits. The first time i cut the side tape, the blade slipped, the stripes were broken, it couldn't be fixed, it was for the monitor。
Now, i'm going to ask you three questions before i answer: are the lights on? Did you hear anything? Are there any flowers or lines? The answer basically knows which ring. Power problems are the fastest and can be measured in 15 minutes; back light depends on the bell reaction for a few seconds; the screen must be removed from the machine for at least 40 minutes。
The switch is getting less and less cost-effective. Last week, when the client said it was a change of machine, i reported 800 for backlight, he hesitated for half a day and finally let me fix it. Two hours after the experiment was completed, it didn't appear again. But i know that the c305 changed is a decipher, with a lifetime of up to six months. I didn't tell him, but i wrote a note: “this is an alternative, like black screen again within three months, and it's repaired free of charge.”
I turned it over, not backtracking the circuit, but looking at how the author wrote, "why the c01 burst caused the 12v instability." he writes that the electrolytic capacity is ageing, that the esr will grow, that it will be too big, that it will filter the texture, and that it will reboot when it's big. I took an esr, i couldn't tell. I bought an esr form, and i measured more than 20 electric caps。
It doesn't sound or smell. It's hidden in voltage, wave shape, heat distribution. You've got to get down there, keep an eye on the rhythm of the flash off the screen, listen to the sound of the electric chip hissing slowly, touch the heat of the flashboard。
There was another black screen yesterday, and i touched the back of the panel, and i burned my hands. 5vsb is normal and 3. 3v falls to 2. 1v. Following the 3. 3v line, a patch pressure stabilizer was found, with a crack in the surface. Squeeze down, change, get electricity, light up, get into the system。
The whole process took 18 minutes。
I wrote a book, and each machine wrote three lines: what symptoms, what points, what changes. It's almost full, ugly, and painted, but turn it back, and it's clear when it's wrong and when it's right。
There's no shortcuts in this business. There's only miscalculation. Welding, welding。
Fix it。
