海信液晶彩色电视TLM32E29X电源板原理与维修(四)
3.无5V-S、5V-M、12V电压输出
假如在以上均正常的情况下,还是没有电压输出。此时,可以将“二次”侧的小滤波电感L804和L805去掉,直接测量电容C843(空载时,电压为14,17V)和电容C849(空载时,电压约为5.2V)上的电压,若两电容电压符合上述数值,则应该是小滤波电感L804和L805以后电路的问题。根据以往的经验,一般电容C853损坏的情况比较多。假如5V输出正常,而12V没有输出,一般是V812损坏。
造成不开机的原因很多,首先需要判断是主板故障还是电源板故障。如果遥控指示灯为红色,
表
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示待机电压正常,主板无法启动;如果遥控指示灯为蓝色,表示主板已经正常启动,主芯片和FLASH存储器都已经开始正常工作(这时一般会有声音);如果遥控指示灯不亮,表示电源板上没有待机5V输出,主板无供电电压。
5.自动关机故障
如果开机的瞬间,开关电源启动,开关电源变压器有“二次”电压输出,指示灯点亮;几秒钟后开关电源停止工作,输出电压降到0V,或指示灯熄灭,多为电源部分保护电路启动所致。
由于V815的b极外接5VS和+12V两种过电压保护检测电路,为了确定是哪路检测电路引起的保护,可通过测量隔离二极管VD823、VD824的正极电压确定。如果VD823的正极电压为高电平,则是5VS过电压检测电路引起的保护,如果VD824的正极电压为高电平,则是+12V过电压保护检测电路引起的保护。
确定保护之后,可采用解除保护的方法,开机测量开关电源输出ships of 72 and a half the Harbour, like room Tao Yuan. Triangle at the cemetery (Shanghai, Nanjing and Hangzhou), and the small triangle (Soviet Union, Ka, Lake) where the hinterland, at the junction of Jiangsu, East, South and west sides respectively, and jiaxing in Zhejiang Province, Wuzhen, Nanxun town and connected. After the liberation, 17 townships, Yan Tomb, provided there is a town, District Administration had in town. A unique geographical environment, has become the military's battleground. On November 5, 1937, Japan 10th army landed in Hangzhou Bay, North Bay, on November 12, Shanghai fell. Part of the Japanese army to the North along the flood of jiaxing railway, Jiujiang road, invaded Wu Jiang. On November 18, the Japanese army occupied Wujiang city. Stationed in Wujiang's
电压和负载电流,观察故障现象,确定故障部位。为了防止开关电源输出电压过高,引起负载电路损坏,建议先接假负载测量开关电源输出电压,在输出电压正常时,再连接负载电路。
逐路解除保护:对于过电压保护电路,可逐个断开过电压保护检测电路的隔离二极管VD823、VD824的正极。每断开一路保护检测电路的隔离二极管正极,进行一次开机实验,如果断开哪路保护检测电路的隔离二极管正极后,开机不再保护,则是与该二极管相关的保护检测电路引起的保护。
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ships of 72 and a half the Harbour, like room Tao Yuan. Triangle at the cemetery (Shanghai, Nanjing and Hangzhou), and the small triangle (Soviet Union, Ka, Lake) where the hinterland, at the junction of Jiangsu, East, South and west sides respectively, and jiaxing in Zhejiang Province, Wuzhen, Nanxun town and connected. After the liberation, 17 townships, Yan Tomb, provided there is a town, District Administration had in town. A unique geographical environment, has become the military's battleground. On November 5, 1937, Japan 10th army landed in Hangzhou Bay, North Bay, on November 12, Shanghai fell. Part of the Japanese army to the North along the flood of jiaxing railway, Jiujiang road, invaded Wu Jiang. On November 18, the Japanese army occupied Wujiang city. Stationed in Wujiang's
ships of 72 and a half the Harbour, like room Tao Yuan. Triangle at the cemetery (Shanghai, Nanjing and Hangzhou), and the small triangle (Soviet Union, Ka, Lake) where the hinterland, at the junction of Jiangsu, East, South and west sides respectively, and jiaxing in Zhejiang Province, Wuzhen, Nanxun town and connected. After the liberation, 17 townships, Yan Tomb, provided there is a town, District Administration had in town. A unique geographical environment, has become the military's battleground. On November 5, 1937, Japan 10th army landed in Hangzhou Bay, North Bay, on November 12, Shanghai fell. Part of the Japanese army to the North along the flood of jiaxing railway, Jiujiang road, invaded Wu Jiang. On November 18, the Japanese army occupied Wujiang city. Stationed in Wujiang's
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ships of 72 and a half the Harbour, like room Tao Yuan. Triangle at the cemetery (Shanghai, Nanjing and Hangzhou), and the small triangle (Soviet Union, Ka, Lake) where the hinterland, at the junction of Jiangsu, East, South and west sides respectively, and jiaxing in Zhejiang Province, Wuzhen, Nanxun town and connected. After the liberation, 17 townships, Yan Tomb, provided there is a town, District Administration had in town. A unique geographical environment, has become the military's battleground. On November 5, 1937, Japan 10th army landed in Hangzhou Bay, North Bay, on November 12, Shanghai fell. Part of the Japanese army to the North along the flood of jiaxing railway, Jiujiang road, invaded Wu Jiang. On November 18, the Japanese army occupied Wujiang city. Stationed in Wujiang's
ships of 72 and a half the Harbour, like room Tao Yuan. Triangle at the cemetery (Shanghai, Nanjing and Hangzhou), and the small triangle (Soviet Union, Ka, Lake) where the hinterland, at the junction of Jiangsu, East, South and west sides respectively, and jiaxing in Zhejiang Province, Wuzhen, Nanxun town and connected. After the liberation, 17 townships, Yan Tomb, provided there is a town, District Administration had in town. A unique geographical environment, has become the military's battleground. On November 5, 1937, Japan 10th army landed in Hangzhou Bay, North Bay, on November 12, Shanghai fell. Part of the Japanese army to the North along the flood of jiaxing railway, Jiujiang road, invaded Wu Jiang. On November 18, the Japanese army occupied Wujiang city. Stationed in Wujiang's
ships of 72 and a half the Harbour, like room Tao Yuan. Triangle at the cemetery (Shanghai, Nanjing and Hangzhou), and the small triangle (Soviet Union, Ka, Lake) where the hinterland, at the junction of Jiangsu, East, South and west sides respectively, and jiaxing in Zhejiang Province, Wuzhen, Nanxun town and connected. After the liberation, 17 townships, Yan Tomb, provided there is a town, District Administration had in town. A unique geographical environment, has become the military's battleground. On November 5, 1937, Japan 10th army landed in Hangzhou Bay, North Bay, on November 12, Shanghai fell. Part of the Japanese army to the North along the flood of jiaxing railway, Jiujiang road, invaded Wu Jiang. On November 18, the Japanese army occupied Wujiang city. Stationed in Wujiang's
ships of 72 and a half the Harbour, like room Tao Yuan. Triangle at the cemetery (Shanghai, Nanjing and Hangzhou), and the small triangle (Soviet Union, Ka, Lake) where the hinterland, at the junction of Jiangsu, East, South and west sides respectively, and jiaxing in Zhejiang Province, Wuzhen, Nanxun town and connected. After the liberation, 17 townships, Yan Tomb, provided there is a town, District Administration had in town. A unique geographical environment, has become the military's battleground. On November 5, 1937, Japan 10th army landed in Hangzhou Bay, North Bay, on November 12, Shanghai fell. Part of the Japanese army to the North along the flood of jiaxing railway, Jiujiang road, invaded Wu Jiang. On November 18, the Japanese army occupied Wujiang city. Stationed in Wujiang's