AMP Not Powering Up or Staying Powered

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mikesw1975

CarAudio.com Newbie
Hi, I'm in need of troubleshooting help for by boat stereo. I have a JL Audio M600/6 amp connected directly to the boat's battery with in-line 100a fuse, also connected to the amp is the 12v remote P.Control wire from a Kenwood radio head. The Kenwood radio head connected indirectly powers up just fine. However, the amp does not power on regardless of the boat's engine running or not. The amp's power connection voltage reads a steady 13.3v at rest, though, after the engine has been running, the voltage reads over 15v leading me to believe this could be blowing the amp. To test the theory, I bought a cheap 6ch amp, and at rest (13.3v) the cheap amp's LED power's up for a brief blip, then goes dark. There are a few other wonky things going on with the power as well like the radio head powering regardless of battery switch position. I've attached a drawing for visualization. Any ideas what could be causing the amp not to power on and thoughts on how to fix it?
 

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Any ideas what could be causing the amp not to power on and thoughts on how to fix it?
Audio equipment is meant to work within 9-16 volts, so 15 volts is no problem. Try refreshing all power connections. You could get a reading above 12v, but once power is demanded, that voltage can drop drastically with a bad connection. As a quick test, disconnect the remote wire, now bridge a piece of wire from Amp Positive to Remote Screw. Amp should power on. When you checked voltage, was the boat on? Some boats run on 24 volts and this may be an issue as well.
 
Thanks for the reply. I refreshed all the connections and still no power at the amp. I also placed the jumper from the 12v+ terminal to the remote term and still nothing. I'm starting to think that the 100a fuse in-line between the battery to the amp may be too big. Strangely, the JL Audio M600/6 amp doesn't have a breaker switch or an on-board fuse for extra protection. Seems like something so expensive would have simple protection mechanisms from getting fried. Regarding voltage, I checked both when the engine was off and when it was on.
 
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Thanks for the reply. I refreshed all the connections and still no power at the amp. I also placed the jumper from the 12v+ terminal to the remote term and still nothing.
Since you said the new amp also protected, the last effort would be to connect the amp direct to your car battery. This will rule out faulty wiring and boat battery if it does not work.
100a fuse in-line between the battery to the amp may be too big.
The fuse is to protect the wire. If the wire grounds out and the fuse is too big, it could cause a fire.
Strangely, the JL Audio M600/6 amp doesn't have a breaker switch or an on-board fuse for extra protection. Seems like something so expensive would have simple protection mechanisms from getting fried.
Most amp's protect circuit will guard against over/under voltage amongst other things, but I think JL still recommends an external fuse near the amp. I hope the car battery test yields good results. I would also test the new amp while you're testing the JL. Keep us posted.
 
I'm starting to think that the 100a fuse in-line between the battery to the amp may be too big.
It would never protect that amp from hurting itself if that's what you mean, but that shouldn't prevent the amp from powering up. If you are not opening fuses when you push the amp hard it is very likely your fuse is too large to keep the amp from harm. Even under-fusing is possibly not enough as fuses can pass a LOT of current before they fail... not for long, but long enough to destroy semiconductors. For example, if you were an amp repair shop trying to get that amp up and running you would be using 3-5A fuse on the power to try to turn it on and do testing. That's about the low fusing required to really protect MOSFETs from detonating if something goes really wrong internally.

As someone else said fuse is meant to prevent a fire if the wire shorts. Amps have """protection""" circuitry to protect themselves but even that isn't 100% fool proof.

Are you quite confident power and ground are both solid and intact all the way to the battery? Clean and tight connections on terminals to the battery? Double check your fuse is still good. It is possible for a fuse to partially open or only look intact and have a hairline break in the element.
 
I'm confident that the power at the amp is steady 13.3v at rest. I've tested at the point of connection at the amp with multi-meter several times.

The 4awg 12v+ (red) cable is connected to the 100a fuse (via distribution block with no other electronics connected); the distribution block is connected directly to boat battery #2 positive terminal. The 4awg neutral (black) cable is daisy-chained from boat battery #1 -> #2 -> audio amp. After running the engine for a while, the voltage reading at the amp goes up to 15v.

The Remote cable is coming directly from the P.Control connection from the Kenwood radio head, steady at 12.7v.

The 100a fuse looks to be in tact. If it weren't, I don't think I would see 13.3v or 15v at the amp.

From what I can tell, the wiring all looks good so I'm stumped as to why (a) I get no LED light-up on the JL Audio amp at all, (b) brand new *cheap* amp LED lights up blue for a brief blip, then goes dark.

I'm going to try two things this week: (1) reduce the in-line fuse to 50a which is what JL Audio recommends in the M600/6 user manual; (2) take the JL Audio amp to another power source and see if I can get it to light up.
 
The fact that the new one only powers on briefly really suggests that there's some other problem going on. 15V shouldn't be an issue for any of this stuff, but isn't great for your batteries, so might want to see if you can't regulate that down to 14.8 unless you're using batteries that are known to tolerate that charge.

Have you disconnected RCAs and speakers before trying to power it up?
 
Yes, the cheap amp only had three wires connected: Positive, Neutral, and Remote. The LED blips for a brief moment and then goes dark.

The M600/6 never powers up, no blip, nothing. So I took it to a local mobile audio shop and they confirmed... it's fried. They suggested I ohm out the speakers to make sure there isn't a short coming from one of them back to the amp. This could explain the dead M600, but it doesn't explain why the cheap amp doesn't stay powered.
 
You should start over from the beginning. Make sure every connection is good, make sure there is no cuts in the power cable that is running back to your area. That can happen very easily depending on the quality of the power cable that you use. Make sure that the bolt you grounded to has no paint and that it is a solid connection. Check the remote turn on wire as well for breaks or cuts in it.

After that just for the heck of it, try running a new power wire without it being hidden with using the fuse holder of course along with a new remote wire and ground wire to another location. One by one eliminate each wire and go from there. Send the other amp for repair. Also make sure the subwoofer or speakers are wired right positive to positive negative to negative and ohm them out as they suggested. I would also try another set of rca cables just for the heck of it if you decided to do all that.

At this point you should just get back to basics and slowly eliminate each wire and go from there. That way if you find hey this power wire works but the other one that is ran already doesn't you found your problem. Idk where in chicago you are and who you took it to but would be interested to know since I am from that area.

Good luck with it!
 
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