I recently inherited a B&W AS6 powered sub (100W 5 ohms) and it doesn't work. When I power on with no other connections, it emits a loud hum. When connected to my receiver, it doesn't respond to any input.\n\nI took off the back panel to look at the amp and there's obvious scorching on the PCB used to connect the transformer and the driver. The other components appear fine (transformer is clean, fuse is intact), so hopefully it's only this circuit that needs fixing. I have no way of knowing if the driver is okay as I don't have any way of testing it.\n\n \n\nI have the schematic for this sub and have marked the components that are within the burned area in the attached image. Visually, none of the components themselves appear obviously bad (resistors aren't burned, capacitors aren't bulging, diodes look clear), but I have no way of confirming their real state without getting some tools. The PCB seems to be the worst off as I can see burning through the layers when held to a bright light.\n\n\n\nI have a couple options and hoping some of you can help advise. Should I:\n\ndiagnose the circuit and replace damaged components? Is it even worth it if the PCB is damaged? What are the chances the printed circuit still being usable? Keep in mind that I don't currently have tools to diagnose but willing to invest a bit as a learning experience.\nreplace the whole plate amp all together with something like the Dayton SPA250? (Note: someone else did a similar modification and it seems to work). It's not too expensive, but will undergo CFO scrutiny.\nshould I look into converting to an external amp instead and keep the cabinet and driver?\n\nIn the meantime I've emailed B&W parts to see if they have this circuit available (doubtful after almost 20 years).\n\nAny input appreciated!\n\nUpdate:\nB&W replied and said they don't stock replacement parts for the sub anymore and referred me to Encompass as a possible place to find a part. Searching Encompass comes up with nothing relevant.