Proficient Subwoofer S12 - No Power

The power supply is working but it is possible that there is no supply to the SUB WOOFER amplifier. It is important to remove and open the unit to probe and confirm.
It can be failure of the inline fusible due to a faulty output driver.
Finally check the subwoofer using a AA cell.

If there is power to the woofer then a signal input must power the woofer to work. So feed a test signal or a audio siignal from a DVD and if there is no output then the AMPLIFIER section had faults.
Unless the sealed unit is opened it cannot be tested to confirm if the output , the input to the AMP or the power supply has failed.
Check if there is power to the output section to confirm.

H?,
You have a very good system...one of the best of SONY..SUB does not get activated automatically especially on STEREO mode.DIRECT STEREO Notes • No sound will be output from the subwoofer.
.your system has Dedicated Power Amplifier for 2 Externally Driven Sub-Woofers (200W RMS x 2)..in order to activate the sub woofer amplifier you need to make a selection on the surround modes while you are switching the modes of the surround you will see the speaker position on the display of receiver as well..if you do not see the sub woofer it wont be activated..Sound Field Program (A.F.D) is a good example to test it..
Take care and please Remember to rate/vote and give me 4 Thumbs Up
for Helping out the Community :)
Hope this helps!
--------------------
Additionally please follow the instruction on your user manual to activate the SUB ,as is follows..
-----------------
BASS-OUT
Low-frequency (bass) signals can be directed to the
subwoofer and/or the front left and right speakers
according to the characteristics of your system. This
setting also determines the routing of the LFE (low-
frequency effect) signals found in Dolby Digital or DTS
sources.
Choices: SWFR (subwoofer), FRONT, BOTH
• Select SWFR if you connect a subwoofer. LFE and
low-frequency signals from other channels are directed
to the subwoofer according to the speaker settings.
• Select FRONT if you do not use a subwoofer. LFE and
low-frequency signals from other channels are directed
to the front speakers according to the speaker settings
(even if you have previously set the front speakers to
SML).
• Select BOTH if you connect a subwoofer and you want
to output low-frequency signals from front channels to
both the front speakers and subwoofer. LFE and low-
frequency signals from other channels are also directed
to the subwoofer according to the speaker settings. Use
this function to reinforce low-frequency signals using
the subwoofer when playing back sources such as CDs.

Call the main office - 877-888-9004.

Pull the speaker and check the coil with a meter. Should read 8ohms. chances are you have a burnt voice coil. They have a 2 year warranty on subs.

with nothing connected and the sub turned on....Most subs buzz when the circuitry starts to fatigue. The last time I heard this ..the repair ended up being one of the two fat capacitors inside the sub. I have a means of testing this,,you may not. I am a repair shop with a bit of experience in component level board repair.

What do you mean that it sometimes doesn't work? It doesn't power on automatically?
Check settings of your receiver - if it has subwoofer output enables and if low frequencies from all channels are directed also to the SUB. By default only the LFE channel (.1) of 5.1 signal input is fed to the subwoofer. So Sub will work in this case only when you listen to 5.1 signal (DVD movie for example), but for radio or stereo music, only front speakers are used. By configuring this bass redirect, you can use subwoofer for all signal types.

I just took my sub apart and found that the surround on the driver speaker inside the sub was totally crumbled and lying in pieces throughout the sub box.

I'm looking around now for specs on the sub speaker so I can find a replacement.

I too am looking for the solution, I'm hoping I have the wrong power cord which is sending too much power to the sub, my next attempt will be to just up the AMP on the fuse b.c hey it's broken anyway

maybe the first step could be checking the subwoofer's fuse.it is located over the power supply connector.