Hello!
I'm repairing DALI Subwoofer with amp board 00-00247-01, which was injured by lightning.
The customer said that it was just humming after that.
So I opened it, checked the board (the board looks perfect, without any damage) for possible shorts on transistors, capacitors, ... but nothing unusual. Everything looks fine.
However, if I look at it with a thermal camera, when I turn it on, the C3117 transistor gets abnormally hot (200+ C), and R126 and R157 start smoking. Although the C3117 npn transistor is tested OK, I replaced it with a new one. I also replaced pnp - A1249 and both resistors R126 and R157.
But the problem remains the same.
Does anyone have any advice on what could be wrong?
Thanks!
I'm repairing DALI Subwoofer with amp board 00-00247-01, which was injured by lightning.
The customer said that it was just humming after that.
So I opened it, checked the board (the board looks perfect, without any damage) for possible shorts on transistors, capacitors, ... but nothing unusual. Everything looks fine.
However, if I look at it with a thermal camera, when I turn it on, the C3117 transistor gets abnormally hot (200+ C), and R126 and R157 start smoking. Although the C3117 npn transistor is tested OK, I replaced it with a new one. I also replaced pnp - A1249 and both resistors R126 and R157.
But the problem remains the same.
Does anyone have any advice on what could be wrong?
Thanks!
