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Discussion Starter #1
I've been slowly building my theater, getting different components when it fits into the budget. My mains are M&K K-7, small bookshelfs with a pair of 4" and a 1" tweeter, so a sub is pretty much a requirement. Having spent my latest theater on my receiver (HK AVR-330), I didn't have the money to spare on the sub that I really want (probably M&K V-75 MKII).


OK, so on with the problem. To hold me over I obtained an old Sony SA-W30 subwoofer for nearly free. It sounds OK, but the one thing that is driving me nuts is that it turns off after only about 3-5 seconds of inactivity. In a theater situation this happens alot. I'm not sure if this is the standard time for standby mode for this model or if it's supposed to be longer, but the delay circuitry has malfunctioned. Does anybody have any experience with this sub that might be able to give me some advice? I have already cranked the sub signal level in the receiver and decreased the gain on the sub itself in an effort to keep a signal to it in some lower volume situations. This has helped marginally, but it's still a problem.


Also, any detailed specs that anyone has on this sub would be much appreciated.


Thanks!
 

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No, sorry. But check for a defeat switch. Some subs of this vintage have a selectable power-down mode. Do you have the manual?
 

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15 minutes is a common power down time for most auto-on featured subs. The timing trigger that determines when they shut off can usually be changed, but only through service. Infinity used to offer modification service to extend their shut off triggers to 1 hour for those who felt they needed it. I don't know what kind of modifications doing such a thing requires, and I'm sure it involves getting inside of the sub. 5 secs is a very odd timer selection, but I can't figure how a malfuction would affect the time. The auto-on feature would most likely fail completely if there were some kind of malfunction.
 

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Discussion Starter #4
Thanks for the responses.


Unfortunately I do not have the manual. I did poke around and followed the path and there doesn't seem to be a defeat for the auto off.


I agree that 5 seconds is an odd time for shut-off and also agree that it's not likely that a failure would shorten the wait time as opposed to just faulting completely. I'm very capable of swapping the timer out if I can identify the correct part to swap (I've replaced v-sync chips, audio amps, etc. in TVs before). I did some searching on what I think is the correct component, but I didn't find anything on the web. I may bring the part number of what I think is the correct component to a local electronics store to see if they can help. Any more information from anybody here would be great!


Also, if this fails I may be looking at a band-aid solution. I've even thought of something as crazy as putting something inline that will push a test tone at a frequency above what the sub will play, just to keep the signal alive. Any thoughts if this will work or not?
 

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One thing you can try...is a very cheap/unshielded cable. If the cable allows some RF or EMI to get thru...you may hear some slight humming with the system off...but at least the subwoofer may stay active because it will see that interference as a signal..:)


Try running the cable right next to a lot of AC cords too..:)


Tom V.

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Discussion Starter #6
Just reporting back to say I found a solution to the problem in case anyone else runs into a similar situation. All I did was soldered across a transistor on the auto shut-off section of the power supply circuit. This effectively defeats the auto-shutoff section completely by causing the transistor to always be in a conductive state so now I have my sub plugged into the switched outlet on the back of my receiver to control power to it. Hope this tip helps someone else in a similar situation.
 
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