Yamaha M-80 Failure

[kjward]

hi folks! i have an old m-80 power amp i tried to use as a dual 4 ohm vc subwoofer amp.
it worked for a few minutes then started smoking, so i immediately turned it off.

have i fried it?

thanks for your help and patience with a newbie!

 

[lovinthehd]

Oh you gotta 'splain more than that, Lucy.

But letting the magic smoke out ain't good.....

 

[kjward]

the m80 input was from a receiver's subwoofer line level output. i connected the amp's speaker outputs to the subwoofer's terminals. right to one 4 ohm voice coil, left to the other. the amp was set to 8 ohm mode. i turned it on at very low volume while a cd was playing through the receiver, and it was producing a very nice bass output...for a few minutes anyway. that's when the "magic smoke", as you say, began spewing from the m80's vents.
is it possible the failure is age related coincidence, or did my connection scheme send it on its way?

 

[Verdinut]

the m80 input was from a receiver's subwoofer line level output. i connected the amp's speaker outputs to the subwoofer's terminals. right to one 4 ohm voice coil, left to the other. the amp was set to 8 ohm mode. i turned it on at very low volume while a cd was playing through the receiver, and it was producing a very nice bass output...for a few minutes anyway. that's when the "magic smoke", as you say, began spewing from the m80's vents.
is it possible the failure is age related coincidence, or did my connection scheme send it on its way?

By connecting both subwoofer voice coils together in parallel to the M-80, that amp was actually driving a 2 ohm load. It wasn't designed to drive a so low impedance and it blew. It is most likely not worth spending money to get it fixed.

 

[lovinthehd]

Well the M-80 does appear to be 4ohm rated but why did you set it to 8 ohm particularly? Can you be more specific on just exactly how they were wired, to what speaker terminals on the amp as well as the driver, also what sub driver? Was this amp working fine in other uses or was it a new-to-you used amp?

Last time I had an amp let out the magic blue smoke, it actually caught on fire and I donated it to the recycling center....

 

[slipperybidness]

I suspect that Post #4 explains the problem, most likely the DVC got wired to a 2ohm load.

Once you release the magic smoke, you can't get it back in there no matter how hard you try.

That amp is likely (well) DONE