45 foot input luminance signal (or composite video signal) into the internal luminance channel, after processing the luminance channel from 37 pin output and send people to 31 feet, again by the luminance channel processing ultimately send to the internal color matrix circuit.

42 feet input chrominance signal (or composite video signal) into the internal chrominance demodulation channel. After chrominance demodulation channel processing get R-Y and B-Y signal, from 35 feet and 36 feet in the output, were sent to IC603 11 feet and 16 feet.

IC603 as the switch, responsible for the internal and external R-Y and B-Y signal to switch. R-Y and B-Y signals are sent by the external video device, plus 14 feet and 1 feet on the IC603. IC603 selects the output of the R-Y and B-Y signals, and sends back to the TB1237AN's 34 foot and 33 feet, and the inner color difference treatment channel. After the color processing channel, send to color matrix circuit, and a luminance signal matrix processing, image of RGB signal. The three color image RGB signal processing channel after processing, from 14 feet, 13 feet and 12 feet to the final output, video amplifier circuit.

23 feet, 24 feet and 25 feet for the three color character signal input, pin 22 character blanking signal input terminal. Characters in the fire control signal hidden under, character tricolor signal is inserted into the image RGB signal, forming effect of mosaic character in the image.

51 foot input signal (or composite video signal) into the internal synchronous separation circuit, the separation of the synchronous signal. Synchronous signal on the one hand from 49 foot output (the machine is not used); on the other hand sent to the scanning processing channel, to ensure the scanning synchronization. The scan channel generates a line scan pulse from 4 pin output, a field scan pulse from 53 pin output. Due to the tb1237an without sawtooth wave forming circuit, so the 53 foot output is frequency rectangular pulse and sawtooth wave form task is accomplished by the circuit.

3 feet for opening and vibration power supply terminal, with a 9V supply. If the supply voltage is lost, the internal scan channel will stop working, three non phenomenon.

Pin 8 is the logic power supply end, designed for internal digital circuit power supply (+ 5V), if the supply voltage is lost, internal I2C bus interface and the DAC circuit will stop working, the emergence of the phenomenon of three.

17 feet for the RGB power supply terminal, designed for internal power supply three color channel (+9V). If the supply voltage is lost, within the three color channels will stop working and leads to 12 feet, foot 13 and 14 pin output voltage is very low, the emergence of the phenomenon of black.

38 pin for the sub carrier circuit power supply side, the voltage is 5V, if the power supply voltage is lost, the sub carrier circuit will stop working, there is no color phenomenon.

41 feet for the Y / C power supply side, specifically for internal channel brightness and chroma processing channel (5V) power supply, if the supply voltage is lost, the decoding circuit will stop working, the phenomenon of black.

45 feet, 37 feet and 31 feet for the luminance signal input or output terminals, normal, 45 feet should be 1V brightness signal (or composite video signal); 37 feet and 31 feet should be 0.7Vp-p brightness signal. Therefore, when the color shadow (i.e. brightness signal loss) fault, by measuring the tripod waveform, can judge the fault location.

The entire luminance channel is provided with 3 auxiliary pins: 39 feet, 44 feet and 2 feet. 39 foot outside the black level to extend the filter circuit, the brightness of the signal of the "light black" level of preservation on the C637. 39 feet external RC circuit failure, will affect the quality of the image, for example: when the of reduction R635 increased resistance or C637 capacity, the image will be black. 44 foot external DC restore the filter capacitor, if this pin is open, can be observed in the black level after the black level extension of the brightness signal, 44 pin external capacitor failure, the picture has little impact. 2 pin external white peak limit set circuit, 2 pin voltage to determine the starting point of the white peak limit, if the external components of the fault, will cause the image to become dark, and even color shadow phenomenon.

27 feet for the color sub carrier output, normal, this pin should be 0.5Vp-p sub carrier, by measuring the foot waveform can be judged by the sub carrier circuit is good or bad.

40 pin 16MHz oscillator circuit, used to generate the 16MHz reference signal. 4.43MHz or 3.58MHz sub carrier is formed by the 16MHz reference signal after frequency synthesis. If the 40 foot external components damage, the sub carrier can not form or frequency offset, there is no color phenomenon. 40 foot peripheral components of the good or bad, the general need to replace the element method to determine the.

30 foot external APC loop filter, the internal APC circuit can be generated by the error voltage converted to DC voltage, and then control the 16MHz oscillator, so that the frequency stability of the 16MHz reference signal. If there is a problem with the external circuit of 30 feet, the frequency or phase of the sub carrier will deviate from the normal value.

29 feet for the contrast control filter side, when the external capacitor breakdown or leakage, the image contrast will be reduced, the image will become light, the level is not clear.

26 foot is the color saturation limit, if the external capacity of the capacitor is reduced or open circuit, it will appear the phenomenon of color instability.

21 feet for half tone control end, under the normal working condition, the 21 pin voltage should be low level (less than 1V). In a half tone state, 21 feet of the voltage between the 1~2V. At this time, halving the brightness and color difference signal amplitude and so can foil character display. If the 21 pin voltage is higher than 2V, there will be no phenomenon of the image.

22 feet for the character blanking signal input, when the 22 pin for the high level, the character signal into the image signal. If the 22 pin external resistor R583 open circuit, 22 feet on the constant for the low level, thus producing the phenomenon of non - character.

16 feet for automatic brightness / contrast control end, reflected beam current size of the ABL voltage by Q585 shoot subsequently added to 16 feet, when the brightness and contrast of the image through the large, low voltage in the ABL, Q585 emitter voltage drop, so that the 16 pin voltage also followed the decline, after the regulation of the internal circuit, image brightness and contrast decreased, which automatically limits the brightness and contrast of the image. 16 foot internal or external circuit is a multiple parts of the fault, when the internal or external circuit fault, often caused by a 16 pin voltage drop, resulting in the phenomenon of image becomes dark. At this time can be 16 feet external circuit is disconnected, 16 pin voltage measurement, if the voltage is about 6.4v, indicating that the internal circuit is normal, fault is due to external caused in the circuit; if the 16 pin voltage deviation from more 6.4v, 16 pin internal circuit fault.

4 feet for pulse output, normally, this pin should be 4.8Vp-p of the pulse frequency, and DC voltage is about 2V. If the foot DC voltage is not normal, or for the pulse waveform, a description of the problem of internal circuit.

TB1237AN internal 6MHz line oscillator, the oscillator by the AFC1 and the digital phase lock loop to control the PLL, the AFC1 loop filter is connected to the 48 pin, the digital phase lock loop filter in the 47 foot. 47 feet and 48 foot external components, often occur when the synchronization range is narrow or not synchronized phenomenon. In addition, the range of the line synchronization will become narrow when the 6 pin is not performed by the reverse side, and the image becomes dark, even in the left (or right) side of the screen.

5 feet for scanning distortion correction, if 5 feet external capacitor breakdown, pulse duty ratio will change greatly, even burned tube.

53 feet for the field pulse output, normal, frequency rectangular pulse this pin should be 4Vp-p, and the DC voltage is about 5V. By observing the foot waveform and measuring the DC voltage of this pin, it can be judged whether the internal circuit is normal or not.

50 foot external field synchronous separation integrated capacitor, when the 50 pin external capacitor damage, the phenomenon will be out of the scene.

If 51 feet external circuit problem, will lead to internal sync separation circuit separation not a sync signal, at this time, seven feet will become to a low level and 1 foot no sand castle pulse output, image is very dark, and synchronous phenomenon.