Selection, detection and substitution of brightness and chrominance delay lines

1. Selection, detection and substitution of brightness delay line

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After the brightness delay line is open or short-circuit damaged, the TV will appear that the image color is not transparent, the brightness and darkness are unclear or the brightness is out of control, the grating is dark, and the contrast is too thick.

When detecting, it can be judged whether it is damaged by measuring whether the resistance value between the input end and the output end of the brightness delay line is normal. Use a multimeter R × 10 kΩ file to measure the resistance between the input and output of the luminance delay line (normal value is 30 ~ 40 Ω). If the measured resistance is infinite, it indicates that the brightness delay line has been internally opened; if the measured resistance is close, it indicates that the internal delay of the brightness delay line is damaged.

After the brightness delay line is damaged, replace it with the same type of delay line replacement or other type of delay line with the same performance. If there is no brightness delay line replacement, you can also make a delay line for emergency repair.

The method of production is:

Take a few aluminum foils and make a rectangular aluminum laminate of 5×10 mm. After inserting a multi-strand core wire, the core wire should be in contact with the aluminum foil. Use aluminum adhesive to stick the aluminum sheet on a plastic rod with a diameter of 80 mm and a length of 120 mm, and then wrap a polyester film on it (using transparent tape). Use a high-strength enameled wire of φ0.08 mm to wrap 1100 T (匝) on a plastic rod coated with a film, and glue two copper wires with a diameter of 1 mm and a length of 10 mm at both ends of the plastic rod (also Use electric iron to heat it into the two ends of the plastic rod. As the lead wire, solder the two ends of the enameled wire to the two lead wires respectively. As the input end and output end of the brightness delay line, the multi-strand core wire connected with the aluminum foil As the ground terminal, as shown in Figure 1. Just wrap a few layers of scotch tape on the wrapped enamel line.


 

Figure 1 Structure of the homemade delay line

2. Selection, detection and substitution of chroma delay line

After the chrominance delay line is open or shorted, the TV has a color "crawl" or color distortion fault.

Whether the chromaticity delay line is short-circuited or not can be judged by the "resistance measurement method". Use a multimeter R × 10 kΩ file to measure the resistance between the pins of the chroma delay line. Normally, it should be ∞ (infinity). If a certain resistance value or a resistance value between two pins is measured, it indicates that the delay line has been leaked or short-circuit damaged.

The brightness delay line is open circuit damaged and cannot be measured with a multimeter. It can only be judged by the “component substitution method”.

After the chroma delay line is damaged, replace the chroma delay line of the same specification and the same model or replace it with other types of chroma delay lines with similar performance (such as phase delay time and center frequency should be the same).

The triode, the full name should be a semiconductor triode, also known as a bipolar transistor, a crystal triode, is a semiconductor device that controls current. Its function is to amplify the weak signal into an electrical signal with a large amplitude value, and also as a non-contact switch.
Transistor is one of the basic components of semiconductors, with current amplification, is the core component of electronic circuits. The triode is made up of two closely spaced PN junctions on a semiconductor substrate. The two PN junctions divide the monolithic semiconductor into three parts, the middle part is the base area, and the two sides are the emitter area and the collector area, and the arrangement is PNP. And NPN two.

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