[mikeypsmith]

Thanks everyone for your help. I have now got the correct schematic and PCB layout. The problem is a bit strange, if I tap the connection with an insulated screwdriver, nothing. If it is not insulated, it makes a load pop and kicks back in, is it an earthing problem I wonder?

I really appreciate any advice given. This is the red wire, by the way, from the playback head. I don't think it carries any dangerous voltages.