Amp being fused by phono's?

**tobz** · 01-11-2009, 08:31 AM

Hello, when my phonos are connected to my headunit on the back of my sub (25a) it fuses almost instantley and sparks. I have notice a bit of capacitance too but I guess thats to be exepected?

The headunit is a jvc one and it has two phono jacks above it, it reads "Line Out", below it "Rear". I connected my phone to these before and sound comes out the rear speakers when played? but not loud it wont get any louder after about setting 8 on sound.

So I connect my phonos to sub from my phone and it all works fine, when my phonos to my headunit are connected zap and the fuse goes! The wiring kits all new and hasn't even been trailed yet so it's all un-scathed.

The sub and amp in question is a Vibe Black Air 12" 1600w with blackbox amp I beleive which is build into the rear.

I have very basic knowledge on the wiring but I am 99.9% sure it's all ok, positive feed goes to battery terminal +, ground to the rear light ground return, remote comes off the head unit blue and white feed.

Remote switching is all ok and the sub has a UV light in it which lights up fine when the ignitions on...!

The headunit is a JVC one, I am beginning to think the headunit is perhaps not meant to run aux speakers like subwoofers?

Sorry!

**hotwire37334** · 01-11-2009, 11:00 AM

Ground Should be of same size as or if not bigger than the positive and direct to body

**jessekilner** · 01-11-2009, 11:19 AM

I would gladly help but I have hard time following your post. I assume you mean you connected the RCA from deck to your amplifier and it shorts out the 25A fuse on the deck or perhaps the fuse panel. But if you don't connect the RCA out, to the amp then it don't pop the fuse. Is this Correct? If it is then I would start by looking @ the amp wiring. The deck would pop the fuse reguardless of amp present if it was the deck. You can do a simple test to verify your problem do you own or anyone you know have a Digital Ohms Meter. You can buy one from Radioshack for dirt cheap and will aid in several area's later on. Once you get your hands on the meter, put either lead on the inner and the other on outer of the RCA jack of the amp (powered on) set the meter for DC. are you getting voltage? IF so your amp is Junk. Sell on ebay I'll buy it and fix..lol if not then try that step on your deck! Either way you should not be getting voltage comming out of the RCA's on the amp. On your deck---> you should not exceed 4V @ full volume. my best guess is it's a wiring issue.

**jessekilner** · 01-11-2009, 11:22 AM

by the way the aux is for input.. you want to hook it to the RCA's labled "Rear" or "fading" or possible "sub" but do NOT connect it to the Aux that would be your problem! Aux is for input to the deck like a Ipod or other external Audio source.

**tobz** · 01-11-2009, 02:46 PM

Right when the RCA's are put into the HU and into the sub the 25A Amp fuse blows. I think I have sorted that now and it was down to a bad ground.

I had a bit of 'luck' earlier I pulled off on of my RCA's and the end fell off I think they may just be poor quality or something.

As I was removing the RCA which hadn't broken when I slipped it off of the HU jack at about 50% of the way off the jack the subwoofer began to play to the song I had playing in the car?

Thanks!

**tobz** · 01-11-2009, 07:39 PM

The ground wire is a little thinner that the power but that could be down to the sheiving size probabley bigger on the power feed (12V+)?

The wires were in a kit by autoleads from UK company Halfrauds (Halfords).
The RCA broke I think their RCA's don't like my head unit as they work when not fully connected but when connected flush I don't get any bass!?

Although theres a BASS light on my Amp which lights up when the RCA is flush (in 100% fully) on the head unit and flush on my amp, but won't play anything but as I say when I do pull the wire out the back of the head unit a fair way it will play bass to a good quality?

Also noticed when turning the sound down the sub makes bassy bang but this is probabley down to the RCA's?

Hopefully I will pick up another RCA tomorow I want to buy a different one not autoleads and see if it makes a difference.

The pack I got was chosen by the Halfords worker and it says 600W on it I think thats what the RMS on my sub will kick out, so all looks good there.

Sorry I am very puzzled and sound like a complete newb!

**tobz** · 01-13-2009, 01:45 PM

Right, I have been told it could be a ground fault but another person seemed to think no chance it would be!

It's not fusing any more, put when the leads go in the HU then nothing happens but I noticed if you put ONE in before the outer gold ring on the RCA it plays but as soon as it's on past the outer ring it won't play and if you do the same with BOTH then I don't think anything plays! But just one 25% in then it will play.

Thanks!