Has anyone had experience with the power / speaker switch on Pioneer SX450 receiver? The switch has these positions: Power Off, Speakers A, Off, Speakers B, Speakers A+B. Starting the amp through my dim bulb from Off to A, the light stays bright and a hum is heard through the speakers. If I turn the knob to the next Off position then back to A, the bulb dims and it works fine. The receiver sounds fine. I suspect there may be an issue with the switch, but it's a very fiddly thing to pull out so wondered if there are any other thoughts about this out there.
Regards John L.
Regards John L.
I doubt it's the switch itself. Seems like you've got an oscillation issue on startup. Once you disconnect the load at full voltage, the amplifier starts behaving itself (though stability is still likely to be marginal).
Test with only one speaker connected to either the left or right channels and see whether this makes any difference.
If just one channel, check bias, check Zobel components, see whether anyone has been there before you.
Test with only one speaker connected to either the left or right channels and see whether this makes any difference.
If just one channel, check bias, check Zobel components, see whether anyone has been there before you.
Thanks for your reply. The bias is "fixed" as there are no trimmer pots and the manual directions say that if the idle voltage is below 15mV to cut the jumper wire associated with that channel. Anyway, I'll check out your suggestions.
Thanks again.
Thanks again.
I tried your suggestion with the speaker leads. With either speaker disconnected the dim bulb lights up, a short hum then it’s ok. Doesn’t matter which channel is disconnected. With both speakers connected the bulb stays bright and the hum stays.