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BeaufortRalph 8th September 2012 07:15 PM

DIYAUDIO Store Speaker Protection
I just finished building the speaker protection board from the store here. I have a mistake somewhere, and need some help troubleshooting the problem.
Upon powerup, both leds light up continuous and the relays close.
I have visually inspected the board and find no obvious problems. I have tested the transistors in place in the circuit and find no shorts.
Introducing dc at one of the amp input points has no effect.

Any Thoughts?

Thanks, Ralph

toastedcrumpets 7th October 2013 06:51 AM

I realise this thread is old, but I'll post one possible solution on here for those who come afterwards. I had exactly the same issue and it was because I bought alternative transistors for the 2SC945's. The pin-out on the 2SC945's is not typical, and is Emitter-Collector-Base. If you use a substitute transistor you do need to insulate and shuffle the legs around.

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