怪,谁能帮忙告诉此镇流器内部线路

Advance RM-2S35-TP Magnetic Ballast (2) F40T12 RS 120V
测试BLUE线同其它的输出线都有280V电压,RED同BULE也有,但是同YELLOW没有.
用LED T8只是BLUE线有输出,RED没有输出...
特请教有了解此镇流器结构的大虾解说一下
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