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[例21] 故障现象 图像上有彩色爬行现象。 分析与检修 用示波器检测NQS01的(19)脚延迟色度信号输入端无信号,检查色度延迟线DL502输出端也无信号,由此怀疑可能是色度延迟线DL502损坏。试用一同型色度延迟线更换DL502后,故障排除。由于DL502损坏后,无延迟色度信号输入,则NQ501不能完成U、V信号的分离,造成了彩色爬行。 [例22] 故障现象 屏幕上只有很暗很浓的彩色,调亮度不起作用。 分析与检修 首先测量NQ501的(23)脚亮度信号输出端电压为10V(正常值应为6.4V)。断开NQ501的(23)脚外接电阻R244,以切断行场消隐信号通过VD203、VD202加入和为防止水平一条亮线而烧伤显像管的场保护电路VQ308与(23)脚的联系,再测(23)脚电压恢复正常,说明故障不在NQ501电路。由此怀疑可能是场保护电路三极管
[Example 21] Problem There is a color creeping phenomenon on the image. Analysis and Overhaul Use the oscilloscope to detect the NQS01 (19) pin delay chroma signal input no signal, check the chroma delay line DL502 output no signal, which may suspect the chroma delay line DL502 damage. Try the same type of chromatic delay line after replacing DL502, troubleshooting. As DL502 damage, no delay chroma signal input, NQ501 can not complete the U, V signal separation, resulting in color crawling. [Example 22] Symptom There is only a very dark, dark color on the screen, and the brightness adjustment does not work. Analysis and Overhaul First of all, measure the brightness of the NQ501’s (23) signal output voltage is 10V (normal value should be 6.4V). Disconnect NQ501 (23) pin external resistor R244 to cut off the line field blanking signal through VD203, VD202 to join and in order to prevent the level of a bright line and burn the picture tube field protection circuit VQ308 and (23) feet contact, retest 23) The voltage on the pin is restored to normal, indicating that the fault is not on the NQ501 circuit. This may be suspected field protection circuit transistor