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1.机型:P2172S故障现象:图像偏紫色,并在亮画面时有拖尾现象。分析检修:(1)图像拖尾,可能是200V末级视放电源电压偏低所致。测试该电压只有170V,更换整流、滤波电路元件、高压包、C506后故障仍不能排除。只有从偏紫色入手了;(2)此机是I2C总线调整,打开调试菜单,看白平衡调整这一项,其中绿枪数据项,数字显示1或2,不能调整。试更换存储块、电脑块后,故障依旧。此时是一头雾水,但也有点突破,就查硬件了;(3)测三枪电压KR、KG、KB,只有KC为170V,与其它两组电压相差甚大,绿枪电压偏高,造成偏紫色。后测尾板上R、G、B三基色输入电压为3.1V、2.1V、3.1V,绿基色放大器明显不正常,问题可能在前级,这时拔掉底板上三基色插头,在底板上测三基色电压都为2.6V左右,可以说明前级正常,故障在尾板上;(4)测V502的b极电压为2.6V,e极为2V(正常b极为3V,e极为2.6V),查偏置电阻R503(100k/1W)开路,更换后一切正常。
1. Model: P2172S Fault phenomenon: the image is purple, and smear in the bright picture. Analysis and maintenance: (1) image trailing, may be the end of the 200V visual amplifier due to low voltage. Test the voltage only 170V, replacement rectifier, filter circuit components, high pressure bag, C506 after the failure can not be ruled out. Only from the partial purple start; (2) This machine is I2C bus adjustment, open the debug menu, see the white balance adjustment of this one, which green gun data items, the number shows 1 or 2, can not be adjusted. Try to replace the storage block, the computer block, the fault still. (3) measured three gun voltage KR, KG, KB, only KC is 170V, the voltage difference between the other two groups is very large, the green gun voltage is high, resulting in Purple. After the test tail board R, G, B three primary color input voltage of 3.1V, 2.1V, 3.1V, green primary color amplifier is obviously not normal, the problem may be in the previous stage, then unplug the three primary color plug on the bottom plate Measured the three primary colors are about 2.6V voltage, can be pre-normal, fault on the tail board; (4) measured V502 b voltage 2.6V, e very 2V (normal b very 3V, e very 2.6V) Check the bias resistor R503 (100k / 1W) open, everything changed after normal.