A 29-inch Skyworth HDTV was brought in for repair, and upon opening the case, it was discovered that the circuit board had a large burned hole. The digital board was also found to be faulty. Since there were no replacement digital boards available locally and the unit couldn't be repaired, I decided to try replacing it with a universal motherboard. The TV uses a double-focus tube, so I first replaced the tube socket with a double-focus one. However, the standard high-voltage package is single-focus, which wasn’t sufficient for the setup. To solve this, I connected the two focus poles together. After connecting all the plug-in parts, the TV turned on but produced a loud line output noise. When I pulled out the deflection, the image looked normal, but when using another deflection coil as a load, the picture was still unstable. This suggested that the issue was related to the line deflection, likely due to low resistance causing an overload.
To fix this, I searched for an impedance-matching transformer and connected it to the high-voltage package. After making this adjustment, the screen finally showed a picture, but no matter how I adjusted it, the image wasn't satisfactory. That’s when I considered modifying the deflection coil. I removed the yoke and carefully examined the row deflection coils, which were originally connected in parallel. I changed them to a series connection. The process involved soldering the ends of the deflection coil with a soldering iron, then splitting them into four wires—being careful not to untangle the three-strand winding, which was made up of multiple fine enameled wires. Using a multimeter, I grouped the coils, marked the ends of each coil, and connected the opposite ends together. The remaining two ends were connected to the deflection lines, effectively changing the configuration from parallel to series.
After reassembling, the image was small and X-shaped. I took it apart again and reversed the head and tail of one of the coils. That did the trick—the image became normal! After adjusting various parameters, the picture was excellent. A long test confirmed everything was working well. Replacing the board on this high-definition TV was a bold attempt, and I believe others who need to repair HD TVs can use this method as a reference. Don’t be afraid of HD TVs or get stuck due to the lack of original parts—sometimes a universal motherboard can work just as well. If you found this helpful, feel free to support it!
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