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Amplifi 150 +-45 volt power supply not present


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Hi there, the power supply doesnt have either + nor - 45 volt power supply present. The other voltages are OK.

First question, for a working unit should there be +-45volt present at the output of the power supply or is there a possibility that it is switched off due to some settings on the amp?

Does anybody have experience in fixing the power board and can recommend where to look as I dont have a schematic.


I suspect that the fault is in one 8 pin chip: 5181 PQAC it gets the output signals from the SG3525AP but I could not find the 5181 anywhere.

Does anybody know what that chip actually consist of ???

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  • 2 years later...



did you manage to fix your AMPLIFi? Mine has a blown transistor, close to that 5181 IC. So blown that I cannot identify it. Can anybody tell me what transistor is in that position? It is the only non SMD transistor, at the other side of the two big capacitors, where I have put the socket you can see in the second picture.


Thanks in advance,


WhatsApp Image 2021-11-16 at 7.40.06 PM.jpeg

WhatsApp Image 2021-11-16 at 7.46.58 PM.jpeg

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