HELP with kit: speaker protection and muting

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I'm working on a kit I can't get to work!

http://www.altronics.com.au/index.asp?area=item&id=K5052
An externally hosted image should be here but it was not working when we last tested it.


I've been meticulous with making sure I have the correct parts in the correct positions, measuring each before inserting ...

It is meant to use a relay to mute an amplifier outputs on turning on, and disconnect on turning off. However, it won't trip the relay! I have managed to trip the relay using a 12V plugpack, so the relay is ok.

Power supply - I have a 12.6V tranny centre tapped. At first I had it with the centre tap, but that only gave me 6V to trip the relay, not enough. So I went with another power supply option, insulating the centre tap and only using AC1 and AC1 from the tranny secondary. This meant putting in 2 extra diodes. Now I check the voltage at the relay contacts, now it is less than 2v!

Previously the muting light went on for 5 secs, then off but there was no click of the relay to go with it. Now after changing the power supply, the muting light stays on! Nothing happens!

What can I say ... I'm lost on this one! I'm semi confident that this thing would probably work fine if there was sufficient voltage at the relay contacts. It's a 12V relay. I'm puzzled that the change would reduce the voltage. Any suggestions from here? ...
 
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