ito pa isa kong na notice sa mga class-H na design,kadalasan nakita ko ung switch para sa high rails ay naka connect sa speaker out lang,ano kaya kung doon tayo mag connect sa outpur ng relay para sakaling may DC out at di mag ON ung relay di rin po mag ON ung switch sa high rails para iwas sa malaking trouble.
gaya ng sa Lexus CA15 pag may DC out daming damay at burn pa ung board.
ano say nyo?
DC-out ba talaga ang cause ng burning ng board ? o epekto na lang ng burning ng board yung "DC-out"?
anyway, i think mas magandang maglagay ng crowbar circuit.
connect the "A2" terminal of the triac to the output inductor. a fuse is recommended between the output node of the output stage and the output inductor. it is also recommended to take the feedback after the fuse.
ngayon kung sakaling magkaroon ng high level dc sa output, ma-tritrigger yung triac shorting out the output and blowing the fuse. some might argue against shorting out the output, it should not be a problem. if the amp is operating normally, the amp will not output high levels of DC and the crowbar circuit will never be activated. "DC out" is mostly caused by shorted output transistors. plus, for sure mas mahal ang speaker kaysa sa output trannies.
audiophiles might frown at the idea of a fuse at the output. no worries, the feedback is taken after the fuse so there should be no audible effect of the fuse.
Note well, the circuit presented may not be suitable for amps with turn-on / turn-off thump as it may be falsely triggered by the thump.
R255 may be reduced to 15k for lower powered amps.