QuestionQUESTION: When the power connections are connected to the amplifier,
the light on top of the amp shows nothing. When i attach the
rca cable, the light flashes blue. I think this is from the
headunit turning on the amp. The blue flashing light means
"b.m.s is activated" but i turned it off using the side
switch. I tried every possible setting with the switches but
the blue flashing light is always there. Can you help?
ANSWER: Hi Brian,
The head unit doesn't turn on the amplifier through the RCA cables; in fact, the RCA cables aren't necessary for the amp to switch on (though they are, of course, necessary for the amp to produce sound). You should be able to get the amp to come on just with the power, ground, and power control connections. If the amp won't power up with these connections, then either there's something wrong with the connections, or there's something wrong with the amp.
The fact that the amplifier turns on when the RCA cables are plugged in means that the RCA cables are supplying something that's missing in the main power connections. This can only be the ground connection--the outer shield portion of the RCA cable is connected to chassis ground through the head unit. Therefore, if the amp is turning on when you connect the RCA cables, that means the amplifier is getting a (very poor) ground connection through the RCA cables. I think it's enough to get the amp to power up briefly, but not enough to keep it working when it starts to play audio. When more current starts to flow through the RCA cables, a severe voltage drop results, which causes the amp to shut down. At that point, the current flow stops, the voltage comes back up, and the cycle starts over again. I think the reason that the power light is blinking isn't that the BMS is active; it's just because you're seeing the amp turn on briefly, shut off, then turn on again, over and over.
In short, I think you need to check the amplifier's ground connection. Make sure it's connected securely to a clean, solid metal part of the vehicle body or chassis. If necessary, scrape away any paint or finish at the ground point, and make sure the connection isn't loose. I wouldn't connect the RCA cables until and unless you can get the amp to come on using only the main power connections--if I'm right, and the amp is grounding through the RCA cables, it could potentially damage the head unit.
Hope this helps!
Brian
---------- FOLLOW-UP ----------
QUESTION: Whoops, I put my question in the comment area, but yeah.. so i
attached the ground to a side part of my car next to the wheel
well. It looks like it's metal, but i tried scraping away at
it, yet nothing was coming off. I also used a zinc plated nut
and bolt to keep the ground secure, would that be a problem?
AnswerHi Brian,
The zinc-plated nut and bolt certainly won't do any harm; the metal is conductive, and it helps prevent corrosion. Usually, if I'm trying to get down to the bare metal at a ground point, I'll use a coarse wire brush that's designed to be used in a cordless drill. Once your ground wire is tightly bolted to the bare metal, it's a good idea to cover the spot with silicone or dielectric grease to keep it from corroding.
I can't rule out a problem with the amplifier; even a poor ground should have allowed the amp to turn on without the RCA connection. Your amp was acting as if there was no ground connection at all. There is a possibility that there's an internal problem that's broken the amp's ground connection. You can test the voltage at the amplifier's power terminals using a voltmeter; if you find around 12 volts on the amp's B+ and power control terminals, using the ground terminal for the meter's black lead, and the amplifier won't turn on, then you'll need to have it serviced. I definitely wouldn't connect the RCA cables to it again until it will turn on reliably using only the power terminals.
Good luck!
Brian
