Amp doesn't turn on


Unregistered guest
I just installed a Pioneer CD player and a Kenwood 640 watt 4 channel amp. This has been my first install that I've done but I think I've done everything right. The CD player appears to be working but I can't get the amp to turn on. I don't understand what's going wrong, I have it grounded, connected to the battery, and the remote wire connected. The fuse near the battery was blown from my other car that it was installed in so I bought another one but I could only get a 50 amp fuse so that's the one that's in there now. The guy said it should still work fine but it should just be harder to blow it. That's the only thing that I can think of. I'm thinking about getting a distribution block because after I get this amp in I'm going to add another amp and 2 subs so I could use it anyways. Will I still need the fuse next to the battery if I get the distribution block or can I get a new wire without it? But still, anyone have any suggestions about what the problem is? I'm going to recheck all my wires tomorrow to make sure it's all connected but this will be my third time checking. Also, I checked the fuse in the amp and it was fine. Sorry if I left out something or something didn't make since, I'm new to this.

Silver Member
Username: Joe718

Brooklyn, NY

Post Number: 215
Registered: May-04
check your remote wire sometimes theres a fuse inline at the head unit, and where you have it grounded is it a good chassis ground?If not scrape away any paint and bolt the wire down, I usually use the rear seat belt bolt. When you add the extra amp your going to need to add up the amperage of both amps an upgrade the fuse upfront then from the distrubution block put the correct amperage fuse to each amp.

Unregistered guest
The fuse under the hood isnt for the amps necessarily.
Its so that If you get a short somewhere,
your car doesnt start on fire.
That fuse stays no matter what.
When you were installing the power wiring to the amp,
you did remember to disconnect the negative
terminal on the battery...right?
has to be the negative one too...positive doesnt count.

Unregistered guest
What do you mean by "has to be the negative one too...positive doesnt count."?

Unregistered guest
If you just unhook the positive
terminal from your battery, you could still
fry stuff.
theres usually a little power stored in the
wire, enough to arc weld your wires to the amp actually..
unhooking the negative terminal will cease all flow.
Just a spark is enough to ruin many things in your amp.

Unregistered guest
Well no, I haven't been unhooking the negative. Now that you say that I'm frightened that I may have fried my amp. I tried doing a few things to get it to work like moving the ground to another part of the chassis, and putting the remote connecter to a 12 volt source. I disconnected all the speaker outputs because the amp has some protection thing where it won't turn on if theres a short in the speaker output. Is 18 gauge good enough for the remote line because that's what I'm using.

Bronze Member
Username: Thrust

Post Number: 23
Registered: Nov-04
remote line is only about 1.5v, not 12v. if you know you're getting voltage to the amp (check with volt meter) and you've checked and re-checked all your connections and still the amp does not power on there's a good chance your amp has a problem.

hi i took one of my broken 4250d mtx amps apart to find what i belive is the mosfets attatched to the heat sink or body of the amp,Completely cracked in half.I would like to replace them but cant find were to get the parts .This should be part of the not powering up prob, Any one know what might have caused this i am thinking it was ran hard befor i got it.

Thanks in advance

Gold Member
Username: Glasswolf

NorthWest, Michigan USA

Post Number: 5709
Registered: Dec-03
those are the FET rails, which constitute the amplification or output stage of the amplifier.
you basically blew the channel out in the amplifier.
you'll need to get the amplifier schematics, and part numbers from MTX to repair it.
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