How do you repair blown Boston Acoustics Subwoofer MCS Amp?

Is it receiving power? If not that is your answer - could be a blown fuse, bad wire, bad connection, etc.

If power is there and it still does not work then the problem coud be with a bad sub woofer on/off switch, internal fuse, or worse, blown amp from over driving.

Is that the right part number, MCS 10, and not MCS100?

The MCS systems use a basic sub which is matched to the satellites. There's very few controls other than level on the MCS100. So as long as the power light is illuminated the there's very little other than the volume control that could be set wrong on the sub. So what it comes down to is either

1. a blown fuse (no power at all at the sub);
2. a broken input (#1 cable, #2 sub input socket, #3 blown sub plate amp);
3. incorrect connection at the receiver end or the wrong settings

As a quick test, unplug the sub cab from the amplifier/receiver end. Switch on the sub and turn the volume down all the way. Briefly put your finger across to short the RCA/phono tip and ring. The sub should make a buzzing sound. You now know that the sub is working and the cable appears to be okay

Switch off the sub and reconnect the phono/RCA to the sub out socket on the receiver. You now know it is connected correctly.

Go in to the receiver's menu and check the speaker settings. Is subwoofer present? Yes/No

Are the satellites all set to Small? (they should be with this system)

Are you playing a 5.1 source in DD or DTS to ensure that the sub gets a signal? Play a BD or DVD.

On the speaker balances, is the sub channel set to 0dB?

As long as all the above is set as listed, then the only things stopping the sub working would then be insufficient volume at the sub's Vol control (so increase it), or an intermittent cable connection (wiggle the cable), or a broken subwoofer out signal at the receiver.

ZD stands for zener diode and used for exact voltage regulation. Take out a known good one and go to a repair shop to replace. Make sure that when you re install, the striped (polarity) markings are in the same direction!

There may be an internal fuse that's blown. I'd take it to a repair facility and have them check it. Could also have a bad connection inside. Good luck!

Is the sub dead? Because this is usually caused by ZD3 being shorted....not the transistors.

Check its speaker connections. Check the speaker using a dry cell. If it is found OK, check the sound settings. If you wish to get more details, check this link.

mine had the same problem until it completely quit. unplug the sub and turn it over, press gently on the speaker cone, does it move freely, or do you hear a sort of scrapping noise? if it moves freely with no noise, its a dif problem than mine. if you do hear the scrapping noise, then theres a short in the voice coil, from what ive read you have to replace the driver (actual speaker part), its basically blown

there should be panels or rubber feet with screws underneath. or the speaker part can come off. that would be where the mesh would be or holes for the sound to escape.

I have the same problem. La Mars covers the factory repair for these. Their number is 712-546-1644. Have you fixed your problem yet ?

Mark