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Audio Mixer Problem.

Zoomup

Hello All, I have a faulty Citronic PRO-3 audio mixer. It runs on 9V A.C. The seller claims that he connected  a D.C. power supply

and after that the mixer produced a muffled output. The input has a four diode bridge rectifier at the input for the power, several

capacitors, and two 7915A three lead regulators plus one 78M05A three pin device prior to the main mixing board.

Any ideas where to look first when attempting a repair?

Thanks,

Z.

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  • 0

    Hi Zoom

    OK I looked it up. 9VAC supply so how does it get more than 15V? The spec says the current is 1A, quite a lot, does it have another transformer in it? Look  at the rectified DC, what voltage? It has USB connections, so thats what the 5V is for, but it also weighs a lot, 3.4 kg, so I suspect another transformer with 9V input. If DC was applied to this anything could have happened!

  • 0 in reply to David Stone

    Hello David, Mike and  G.K. My model has no U.S.B. sockets just phono sockets. I guessed at the 4 diodes making a bridge, I may be wrong there. There is nothing burnt or blown up that can be detected by eye. I am awaiting a suitable 9 Volt A.C. power supply before I can test this unit. I will report back. I suppose that I could use an 8 Volt bell transformer to test it. There are two big electrolytic capacitors rated at 35 Volt near to the 4 diodes and some smaller ones, so perhaps these are used to produce the 15 Volts needed.

Reply
  • 0 in reply to David Stone

    Hello David, Mike and  G.K. My model has no U.S.B. sockets just phono sockets. I guessed at the 4 diodes making a bridge, I may be wrong there. There is nothing burnt or blown up that can be detected by eye. I am awaiting a suitable 9 Volt A.C. power supply before I can test this unit. I will report back. I suppose that I could use an 8 Volt bell transformer to test it. There are two big electrolytic capacitors rated at 35 Volt near to the 4 diodes and some smaller ones, so perhaps these are used to produce the 15 Volts needed.

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