Troubleshooting ideas for the hottest West Lake mo

West Lake E-Cell color TV troubleshooting ideas

the E-Cell color TV produced by West Lake Electronics Group adopts the integrated circuit ta8690an, and the models include ce2169, ce2138, ce2100c, ce1418, etc. This (2) LCD Chinese character display text is based on ce2100c color TV, and introduces the maintenance ideas of common faults of this series of core color TV

I. The failure of image if circuit generally shows that there is a blue background and "West Lake Cenozoic" characters, but there is no image or accompanying sound, the image sensitivity is too low, and there are phenomena such as drift and distortion

1. the normal working state of the pre discharge pipe, VC ＝ 8.4vvb ＝ 1.2vve ＝ 0.4V. When the pre discharge tube is damaged and the surface acoustic wave filter is open circuit, there will be no image and no accompanying sound. The interference method or 0.01 can be used μ F capacitance shall be checked by parallel connection method

2. Pins ⑥ and ⑦ of integrated circuit ta8690an are intermediate discharge AGC voltage. When the voltage of this pin is abnormal, such as the leakage of capacitor c235, it will change the response time of the circuit, affect its working state, and make the AGC voltage sent to the tuner inaccurate, resulting in reduced sensitivity

3. The AFT voltage of the slip pin of the integrated circuit ta8690an is abnormal. If the capacitor C201 leaks electricity, the output signal of the tuner will deviate from 38mhz, which will cause abnormal images and accompanying sound, and easy to cause station escape (if the slip pin and slip pin external resonance circuit are detuned, this kind of fault will also be caused)

4. when rfagc voltage at the third pin of integrated circuit ta8690an is abnormal, such as capacitor C104 leakage, rfagc voltage will be out of control, causing distortion in the upper part of the image

second, for no accompanying sound fault phenomenon, the following checks can be carried out:

1. When the capacitor C201 is open circuit, there is no accompanying sound signal input at the second pure pin of the integrated circuit ta8690an, so that the second accompanying sound if signal separated from the video signal cannot be sent to the internal limiting amplifier

2. When the external capacitor c232 of the ⑤ pin of the integrated circuit ta8690an is open circuit, the second accompanying IF signal cannot be sent to the frequency discrimination circuit

3. when capacitor c233 is open circuit, the frequency discriminator cannot demodulate the audio signal

III. for binocular metallographic microscope with common accompanying sound, it can inspect the truth with two eyepieces:

1. To accentuate the failure of capacitor C231

2.l209 frequency discrimination coil detuning, such as the leakage of the internal capacitance, causes the frequency offset of the 6.5mhz sound signal

IV. for the failure phenomenon of dim grating or horizontal bar interference, if the brightness signal is lost or interrupted due to the problem of the brightness signal channel, the following inspection can be carried out:

1. The peripheral components of the brightness signal input end are damaged, resulting in the failure to take out the brightness signal from the full TV signal, such as the open circuit or poor brightness delay line D202

2. No brightness signal output, such as V205 breakdown connected externally to the third pin

3. The capacitance loss of the brightness clamping capacitor c205 of the third pin affects the working state of the internal brightness circuit

v. for no color and abnormal color, the following checks can be carried out:

1. The colorless signal input of the pure spinning leg, check the color band-pass filter and coupling capacitors C219 and C225

2. Check the system conversion circuit and the primary color subcarrier circuit outside the pins of the system. When the VCO component fails, such as the crystal oscillator G205 does not have high transparency, excellent mechanical properties, high thermal deformation temperature and good halogen-free flame retardant characteristics, the oscillation stops or the frequency shifts

the person in charge also said that 3. Check the PAL line delay circuit outside the pin. For example, the chroma delay line d210 is bad or C212 is open, so that the delayed chroma signal cannot enter the pin

4. check whether there is chromatic aberration signal output at the foot of 紒紣矠, 紒矠, 紒紥矠. If the DC voltage of a pin drops and the peripheral components are normal, the color difference signal of the pin is output

5. Check the APC voltage of the subcarrier pin. If the external RC component fails, the oscillation frequency of the VCO cannot be synchronized with the color synchronization signal

6. The color saturation control circuit should have a DC voltage change between 3.0-5.1v when the color is adjusted normally. If not, check the interface circuit between the CPU and the pin

for each fault phenomenon, if the relevant peripheral circuits and the working voltage of each part of the circuit are normal, the internal circuit of the chip is generally damaged and should be replaced