StudentSA
Member
Good Day,
I hope I can find some assistance with the repair of a KEF KUBE-2 Subwoofer circuit board.
When taken apart I found two boards linked via two connectors. The top board held the audio input,volume control,crossover control knobs. I assume this top board is used to prepare the audio signal for injection into the amplifier board via one of the connectors. The other connector head appears to pass power to this top board and has 5 pins labled (+18,GND,-18,MODE,AGND).
In order to find which board is faulty I applied the +18,GND,-18 to the top board and the power LED came on as normal. So I decided that the issue must lay in the bottom (PSU and AMP) board.
When I apply AC to the bottom board, get 230V at the Full Wave Bridge Rectifier and 300V DC as the filter cap.
I also found that the power supply header for the top board is putting out 14-16V from the +18V pin and close to zero from the -18V pin.
I am having trouble understanding how the PSU board is creating this 18,-18 volt supply from the 300V DC.
Please could you advise what I could check next.
Top of Board
**broken link removed**
Thanks,
StudentSA
I hope I can find some assistance with the repair of a KEF KUBE-2 Subwoofer circuit board.
When taken apart I found two boards linked via two connectors. The top board held the audio input,volume control,crossover control knobs. I assume this top board is used to prepare the audio signal for injection into the amplifier board via one of the connectors. The other connector head appears to pass power to this top board and has 5 pins labled (+18,GND,-18,MODE,AGND).
In order to find which board is faulty I applied the +18,GND,-18 to the top board and the power LED came on as normal. So I decided that the issue must lay in the bottom (PSU and AMP) board.
When I apply AC to the bottom board, get 230V at the Full Wave Bridge Rectifier and 300V DC as the filter cap.
I also found that the power supply header for the top board is putting out 14-16V from the +18V pin and close to zero from the -18V pin.
I am having trouble understanding how the PSU board is creating this 18,-18 volt supply from the 300V DC.
Please could you advise what I could check next.
Top of Board
**broken link removed**
Thanks,
StudentSA
Last edited: