Sub Appears to come out of standby mode but no sound

[Scuzzi]

I have a KSW-10 purchased 16 years ago.  With the sub in auto mode (also happens if the sub is in "on" position), the sub will appear to come out of standby mode (light on front of sub changes from red to green) when a reasonable strong bass level is being emitted from the Yamaha TSR 5790 av receiver. However the sub emits no sound. I can change the volume setting on both the sub and the receiver, but neither appear to have no effect on whether this occurs/changes or not.  HOWEVER, if I leave the receiver turned on playing music (this happens regardless of whether I am playing music or video with audio content) and leave the sub in "auto" mode,  but then unplug the sub power cord from the wall and then plug it back in, the sub then emits nice strong base response. I am using one of the sub outs on the receiver, but have the same problem with either one. I have the other end of the sub cable plugged into the L/LFE and R inputs on the sub, but have tried just the L/LFE with the same results. This also happens with an older model Yamaha receiver. It's a real pain to unplug and replug the receiver once the system is turned on every time I want to use the sub. Very occasionally (probably less than 5% of the time), the system will work as expected without my intervention. Any ideas? 

[efzauner]

Lets isolate some things here.
First lets get the auto on circuit out of the way. 

Does it work at all in normal (not auto on) mode?  If so, then there is something wrong in the auto circuitry

If it shows same issues on both on and auto mode then could be an issue somewhere else with turn on delay etc. You would have get it repaired.

 

E

[atheod]

Exactly same issue for my sub KSW-10.

Anybody?