I changed out my subwoofer since I managed to run a nice crack from the cone to the surround when I decided to give it a workout. I put the new amp in without double-checking (+) and (-). Four wires, four terminals on the sub, and single voice coil So what I basically did was have both a (+) and a (-) on each woofer terminal.

Now when I turn the amp (acc) on, I get a single clip and no noise after that. There is no protection mode LED but the power LED intensity waivers slightly (i.e. strong->weak->strong). I have it bridged as usual, but when moving the woofer to the right channel only, I get some strong spark on first contact with no noise afterwards.

Any ideas? This is an MTX 2300x (600w rms @ 12v) so I'd REALLY like to salvage it. It was at about 3/4 max gain when I hooked up the 2nd woofer

7/19/2006 12:03:22 PM

So you essentially short circuited the output?

7/19/2006 12:39:30 PM

did you check the fuse?

7/19/2006 1:10:40 PM

i'm tryin to figure out wtf u had wired up. if it's single vc why does the sub have 4 terminals and why'd u run 4 wires??

check your wiring then check it again. you may have blown the output stages orf the amp. good luck man

7/19/2006 2:22:29 PM

My bad, the "four terminals" on the svc sub are actually just two terminals with two tabs each.

the "four wires" are two sets of wires which are just split off from the same source like this:

amp out (-) --------<======= (-) sub
amp out (+) --------<======= (+) sub

I criss-crossed the wires going to the sub (short circuiting the output, yeah)

yeah, I checked the external fuses (3x30amp) and all were fine. I didn't see any internal fuses when I opened up the amp but I did not pull all the circuitry out to inspect the bottom of the board. But I've never seen fuses on the bottom of a circuitboard so..

^is that fixable? how easy/hard/possible? thx

7/19/2006 3:39:30 PM

Seems to be the case that you blew up the output stages. You might can be able to swap some new ones in if you are lucky.

Take a multimeter to the gate and drain and see if you get zero ohms resistance, or very low.

7/19/2006 5:47:21 PM

I'll do that if you tell me exactly what the gate and drain are

Google results are too technical for me, but if there's an easy way to describe both, i'd be much obliged if you do so. I'll try to get a pic of the internals tomorrow

7/19/2006 9:53:20 PM

for future reference...when a sub has one set of terninals with two tabs on each terminal, you don't have to split your wire to hook on to both tabs.

the double tabs are there so that you can wire speakers in series or parallel without splitting and splicing wires.

7/20/2006 7:37:12 AM

QUESTION NO. P222-6: How does one test FETs using a VOM?
You did not state if the FET is in the circuit or out. And assuming it is a MOSFET, if the FET is out of the circuit, gate to source resistince should be many megohms, both polarities. An N type Mosfet will be several megohms with the ohmmeter positive lead on the drain if gate and source are connected together and to negative lead. Reverse the leads and read a diode drop.

7/20/2006 3:37:04 PM