Hi. I've bought a new car and my subs don't work. I don't dig into audio stuff, but I do have a multimeter and a couple of hands. So, the setup is: nakamichi cd-45z head, speakers are connected right into the head. blaupunkt gta 4100 amp in the trunk, two 2xRCA cables coming in from the head unit, two subs on the outputs. The red protection light is constantly on, the green power light is off. Once in about 4-6 seconds the red light goes off for a moment, the green one goes on and subs produce a thump (doesn't depend on what is playing or the volume on head, the same even when volume is 0). Then red light again... I checked the ground and +12v terminals with my multimeter, seems ok. So, is my amp fried, do I have a short circuit somewhere (maybe subs are fried?) or any other ideas? Willing to disassemble and check everything out. I checked all the connections to the head unit, they're ok, so unless the cables are cut somewhere in the middle, the head->amp connections should be ok.
update: I've got 2 4-ohm woofers (ivolga drive 8f), checked the resistance with multimeter, they're fine. I've disconnected amp from everything but ground and +12V, and wired +12V and remote. Result: protection light always on, so something's wrong. Multimeter reads 12V between +12V and ground, so I guessed the wires should be ok. I took the amp home to try and disassemble it. One idea leapt to my mind - try to connect it to a 12 VDC power adapter. I only found 9 VDC adapter, but multimeter showed it outputs 11 volts... ****ing quality. So, I wired the adapter to my amp, and voila - green light, it seems to work fine. Tried wiring it to the car again this morning - doesn't work again. So, what could be the problem? I mean, there indeed is 12 volts on the wires... Could it be that my battery has gone bad (I had no other electrical problems, though)? By the looks of it, it can be older than 4 years.
check the earth connection for the amp is a GOOD one where the earth cable joins to the car. I had similar things before, there was a connection, but just not enough of one. my amp just sat there playing nothing and saying everything was fine, mind you, so its not exactly the same.
Thanks, for the suggestion. I checked it somewhat, with a multimeter. I.e. touched the wire near the amp and the body of my car in some place, very little resistance. What do you mean "there was a connection, but just not enough of one"? Is it possible?
yeah earth is usually the main problem with things like this it needs a good earth not just an earth other thing how have you got your subs wired what load are you showing the amp ? also check the permenent live is working as the remote live can power the led's sometimes other than that try it on another setup which you know is working as it could be faulty
it needs a very good connection to work otherwise they just flick into protection mode, although sometimes you can get them going on and off constantly whilst driving. check earth on amp and also check the earth on the stereo, had that before, where earth was fine on amp, but the earth for cd player wasnt the best, was good enough to run cd player, but not cd player and amp. failing that you might have trapped the remote cable and it might be shorting itself out. it could also be a dodgy rca cable (red and white ended cables from cd player to head unit) they could be dodgy, had so many problems before with one of my cars because of that, replaced that, never had a problem since. or your speaker cables on head unit or amp could be touching and shorting out check earth first thow
Yes make sure you check the ground and keep it to as close to the amp is possible. Find a flat space on the metal sand all the dirt, paint off till you see nothing but bare metal and bolt down. I saw you say you tested the subs with a meter and the both tested 4ohms.? Did you test them where the wire connects to the amp or at the speaker terminal? Reason being is the sub might be a good 4 ohms but maybe wires might have been crossed somewhere and chaged the resistance or a bare piece might be somewhere and rubbing up against metal? Also check them when the have power to them as well as off. Check the ohm level coming out of the speaker leads on the amp and the Rca cables. You might have a bad set of RCA's or something might be blown in the amp. Last thing to check is to make sure the speakers aren't out of phase. What I mean is if you have one sub hooked up positive to posite and neg to neg and the other pos to neg and neg to pos it with throw off the resitance and send the amp into protection mode. Check the same thing with the wiring if you have bridged the amp crossing wires will drive an amp crazy. I gave you every possible solution there is for this and I hope it's the easiest and cheapest fix. Good luck if you need more help e-mail me.
Everyone, thanks for suggestions. I checked all aforementioned things. RCA cables and speakers are definitely not the thing here, the amp doesn't work even when they are all disconnected. I removed the ground bolt, naked some fresh cable, polished the everything with sandpaper and reconnected, it's definitely good now (still doesn't work). The last thing I did was to measure the current going thru the amp by wiring my multimeter in 10A mode in series with power wire and amp power input. The result: when I turn my key to ACC (amp's power is wired to ACC), amp turns on (green light), the current is around 1A, then the current gradually increases (quite fast) - after 2-4 seconds the current is somewhat more than 6A then the protection kicks in. I wired my amp to DC adapter again at home, the current is 0.4A, this is probably the max current my DC adapter can output. So, is there some problem with the amp (i.e., is >6A normal for it to take?), or too weak an accumulator? If so, I wonder if the starter uses <6A ???
First you don't have to go anywhere but here! Now you said your amp is wired to the Acc. power? Now is this your main power thats wired to the Acc. or the amp turn on? Your main amp power should be connected to the battery directly not taped off something else, your remote turn on wire should be connected to the amp turn on lead on the back of the radio, a toggle switch or if need be but not recommended and acc power source (keyed/ignition power supply). You did good with the ground. What is the ohm reading at the speaker terminal at the amp with the subs connected and the reading without them connected? now you say your power spikes rather fast? again that leads me back to where is the main power supply connected to? Listen you got me hooked on you problem now lol so I'm going to help you nail this down but I need as much info as possible. If you don't want to keep posting thats fine but e-mail me (address down below) and will get this fixed one way or another. Talk to you soon and please give me those readings.
