Brutus 1206D started squeaking (like a bird) today

[rurockn]

My Brutus bxi1206D started making the sub squeak today, in a way that I've never heard a sub/amp make noise. It's not a whiney ground issue, I've had those before and this sounds nothing like that. This time you can see the woofer cone shake in and out slowly and the sub literally sounds like a squeaky door opening and closing or a tiny bird chirping. Also, if you turn up the volume it still powers the sub fine, but it makes that squeaky noise.

I opened it up and replaced a few leaky capacitors, however, that did nothing to alleviate the squeaky noise. I looked more closely and found a lead on one fet that wasn't even soldered! wow! So I soldered that and it still squeaks.

Any thoughts? Thank you!!

[Perry Babin]

Does it have the same problem with no RCAs plugged in?

[rurockn]

With both unplugged, there is no noise. It also increases linearly with volume; to a certain extent and then plateaus. I didn't think of plugging one in at a time.

I also tested it on my bench to eliminate issues related to the car/wiring and it does the same thing running on a power supply at my work bench.

[Perry Babin]

Did you confirm that the RCA shield of the head unit is intact?

RCA Shield Repair

Is there any DC voltage on the RCA shields of the amp?

[rurockn]

There is no voltage on the shield.

[Perry Babin]

Did you confirm that the RCA shield of the head unit is intact?

[rurockn]

Both the amp and head unit shielding have no voltage.

[Perry Babin]

You need to confirm (with a multimeter, set to ohms) that the shield on the head unit is intact.

[m4ick]

Perry, I believe you've solved this one for me before.

This sounds like the same issue I had with a 1206d, the sound it produced sounded like an Atari and if you push on the sub by hand with the amp turned on it sounds like the coils are rubbing except that it was "squeakier" than normal coil rub. When I opened it there was no drive signal to any outputs.

If that's the case it may be Q11 or nearby resistor on the driver card. In my case it was a 270ohm smd resistor tied to Q11.

[m4ick]

Now that I think about it, my issue may have been Q11 AND the resistor because blindly replaced Q11 first, when that didn't fix it I found an open resistor tied to it.

As a side note I'm not sure if unplugging the RCAs would've stopped the noise on mine but I could see how a small amount of signal could make the problem apparent. I took it straight to the bench and saw no drive signal so I had no need to feed a signal into it at that point.