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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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Repair of Creative Labs DTT2500
Hi
I am currently attempting to repair my Creative Labs Desktop Theatre amplifier, I am getting no output from the Subwoofer channel, if you run the speaker test this again provides white noise in turn on each channel but no output on the subwoofer. (Yes I have confirmed that the speaker is working ok) Unlike the other 5 channels the subwoofer does have a line out, if I connect an amplifier and speaker to the subwoofer line output and run the speaker test I do get output on all 6 channels therefore I believe the decoder card is working correctly. I have dismantled the unit and checked all connections they visually appear to be ok, also the unit is on two PCB's a decoder pcb and the 6 channel amplifier pcb, the subwoofer line out is also on the amplifier pcb therefore the signal must be getting that far. If I touch the input pin of the subwoofer power amp IC I get the expected mains buzz, therefore I am fairly happy that the power amp chip is working. Therefore it must be in the preamp stage someware. I did try to obtain the circuit diagram from Creative but they said, "Unfortunately I cannot give you a circuit diagram of the amplifier. We don't supply this kind of information" which was polite but not very useful. Before I sit down at attempt to trace the circuit out I was wondering if anyone had already done this. Also each channel has an 8 pin IC marked 072D and JRC, I dont recognise JRC but I am wondering if it is a dual opamp like a TL072, from what I have traced of the circuit so far it does look possible. Has anyone had any experience repairing one of these, or recognise the chip. Thanks Dave |
#2
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Repair of Creative Labs DTT2500
Just in case anyone was interested, I found a dry joint and it is now
working fine. Dave "Dave Widgery" wrote in message ... Hi I am currently attempting to repair my Creative Labs Desktop Theatre amplifier, I am getting no output from the Subwoofer channel, if you run the speaker test this again provides white noise in turn on each channel but no output on the subwoofer. (Yes I have confirmed that the speaker is working ok) Unlike the other 5 channels the subwoofer does have a line out, if I connect an amplifier and speaker to the subwoofer line output and run the speaker test I do get output on all 6 channels therefore I believe the decoder card is working correctly. I have dismantled the unit and checked all connections they visually appear to be ok, also the unit is on two PCB's a decoder pcb and the 6 channel amplifier pcb, the subwoofer line out is also on the amplifier pcb therefore the signal must be getting that far. If I touch the input pin of the subwoofer power amp IC I get the expected mains buzz, therefore I am fairly happy that the power amp chip is working. Therefore it must be in the preamp stage someware. I did try to obtain the circuit diagram from Creative but they said, "Unfortunately I cannot give you a circuit diagram of the amplifier. We don't supply this kind of information" which was polite but not very useful. Before I sit down at attempt to trace the circuit out I was wondering if anyone had already done this. Also each channel has an 8 pin IC marked 072D and JRC, I dont recognise JRC but I am wondering if it is a dual opamp like a TL072, from what I have traced of the circuit so far it does look possible. Has anyone had any experience repairing one of these, or recognise the chip. Thanks Dave |
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