Im about to blow my fuse! (Sub Install problems) (REPLACEMENT WORKS!) - Page 3 - Saxperience

Ashleyp · 29th July 2008, 19:31

lol at the idiot who suggested RCA's

they dont carry any power atall, how can something with no power blow the fuses!?

RK_Audio · 29th July 2008, 19:33

this one has actually got me stumped to be honest. the only thing i can think of is that a wire is shorting out somewhere

Alarming_Sounds · 29th July 2008, 19:42

if you were close to me i would say pop round and i will have a butchers, time to take it to a shop i think at worst i would think £25 max for them to have a look.

Oroblram · 29th July 2008, 19:56

Quote:

Originally Posted by RK_Audio

this one has actually got me stumped to be honest. the only thing i can think of is that a wire is shorting out somewhere

That is just it, the sub powers up fine on its own and both head units work fine.

Only when I connect the sub and the head unit (tried with 2 different RCA cables now with and without the normal speakers / aerial cable connected) does the fuse blow.

I really don't know where to go from here, all the wiring checks out, the components work standalone but not together.

Could the head unit be grounding out via the RCA's to the amp?!?

Ashleyp · 29th July 2008, 19:58

Quote:

Originally Posted by Oroblram

Could the head unit be grounding out via the RCA's to the amp?!?

i doubt thats possible tbh

Oroblram · 29th July 2008, 20:04

The piccy of my sub on the VIBE website shows a "GREEN"!!? fuse.. 30 amp fuse right?

Why did mine come with 2 x 25A fuses?!?

Oroblram · 29th July 2008, 20:26

Right on the subs rear it shows 25A, it came with a 25A fitted, it worked in the store with a 25A fitted.
On the website it shows it with a 30A fuse fitted, in the Manuel it shows a piccy of it with "35A" wrote on the fuse area of the sub, but then says you should use a 25A fuse.

Ashleyp · 29th July 2008, 20:38

Quote:

Originally Posted by Oroblram

Right on the subs rear it shows 25A, it came with a 25A fitted, it worked in the store with a 25A fitted.
On the website it shows it with a 30A fuse fitted, in the Manuel it shows a piccy of it with "35A" wrote on the fuse area of the sub, but then says you should use a 25A fuse.

sounds like a french person designed it lol

maybe the 25a fuses are too weak and blow at anything

bigger fuses needed maybe? to handle the current

McBain · 29th July 2008, 21:05

I wouldn't bother changing the fuse to a higher rating tbh, if it's blowing 25s just on stand-by it'll probably do the same with 35A fuses too, and with greater chance of causing damage.

I would suggest you recheck the head-unit wiring, did you run a new earth to the hu as suggested in a previous post?

You've determined that the sub is working by a bench test in a shop and that the head-unit works also by a similar test , so I reckon you've got a wiring fault somewhere.

Also, you're sure you've connected your RCAs to the head units pre-out and not the aux-in?

Stu.

Coonper · 29th July 2008, 21:31

Pop the bonnet and wire it al up on the floor!

Pos from battery to amp, earth it to the neg terminal on the amp, strap a wire from power to remote, then see what happens!

This will tell you if you're wiring is at fault. You can also stretch an RCA lead from the head unit to the sub while you are testing it!

DJDannyB · 29th July 2008, 23:59

Quote:

Originally Posted by Ashleyp

lol at the idiot who suggested RCA's

they dont carry any power atall, how can something with no power blow the fuses!?

Vibe did. But, he said it happens when he plugs in his rca.

something weird going on with it if you ask me mate.. cant think of anything that it could be.

Oroblram · 30th July 2008, 00:54

Ok, I got some more fuses from the 24 hour garage, not had much time to work on it but I did manage to re-ground the amp and still no change.

I'm going to go back to the shop tomorrow.

So far I have spent about £10 on fuses, £100+ on a new head unit and £12 on new RCA leads, not to mention the £260 the amp/sub cost in the first place.

I'm getting out of patience now and just to top it all off one of my exhaust mountings has decayed and the bloody thing is tied up with string.

Oroblram · 30th July 2008, 09:14

Just got off the phone with Vibe again, there support is great but they cant help me since they think it is my car wiring.

Oroblram · 30th July 2008, 21:57

Tonight I had a major break through!

I got my multimeter out and after a quick trip to Tesco for a 9V battery I was back outside my house poking things with the multimeter.
The multimeter has lots of Ohms settings, Tone, 200, 2k, 20k and so on.
Connecting the neg from my amp to the body of the car gave me a rating of 00.5 on the "200" setting and 0.00 on the "2K" setting.
Connecting the neg from my head unit gave me a 0.01 on the "200" setting and a 0.00 on the "2K" setting.
Connecting the neg of the RCA leads (Amp end) gave me a 0.03 on the "200" setting and a 0.00 on the "2K" setting with the leads plugged in to the HU at one end and the multimeter on the neg of the other end (The outside of the RCA plug)
This lead me to believe that there is less resistance from the amp to the HU then from the amp to the grounding point.
Now if I remember my GCSE science correctly then electricity will always take the path of less resistance, and so the amp was trying to ground via the HU through the RCA's.

Now those of you that have been following this story will know I have 2 sets of RCA leads, a good set that came with the amp and a cheap set that I picked up to test with.
I tested the RCA cables and found the cheap set of leads had the highest resistance (Surprise, surprise) so I hooked them up to the HU and powered everything up.

I then connected the left RCA (Black) to the amp leaving the right one disconnected since I figured this would not allow as much voltage to travel down the RCA ground.

It worked! For the first time ever I had the rich bass pumping out of my sub!
Not for long thou, after about 10 seconds the RCA cable started to get very hot to the touch so I quickly unplugged the amp.

I believe this pretty much confirms that the amp is indeed grounding out via the RCA's and in turn the HU, but what I don't understand is why the HU is not effected by this.
Surly the HU neg being only a thin cable should not be able to handle 25A (The power required to trip the fuse) so this leads me to believe only part of the current is being send via the RCA's?

How does the HU still keep working when there is a positive current flowing down the negative of the HU?

Just to confirm I tested it again first with one RCA plug attached and again it worked, then quickly I plugged the second RCA plug in and the fuse instantly popped.

I hope the above makes sense and please correct me if any of it is totally wrong.

How do I go about getting a better ground for my amp then the one I already have (See previous posts)

Oroblram · 30th July 2008, 21:57

Ignore this, it double posted for some reason?

Noddy · 30th July 2008, 23:11

Going by what you;ve jsut said, i'd now say that the amp is buggered to be honest. If its grounding out via the RCA's then i must be an internal wiring fault.

Oroblram · 30th July 2008, 23:23

Quote:

Originally Posted by Noddy

Going by what you;ve jsut said, i'd now say that the amp is buggered to be honest. If its grounding out via the RCA's then i must be an internal wiring fault.

How come it worked in the store thou?

If the in-store HU ran off one transformer and the amp was being powered by another (No shared common ground) would this make a difference?

It was on in the store for at least 5 mins with no problems.

Noddy · 31st July 2008, 00:19

ah i missed that bit, i'll re-read and have another think...

Oroblram · 31st July 2008, 08:45

Should an amp ever try to ground via the RCA's if a normal ground is present?

Oroblram · 31st July 2008, 11:46

Vibe have confirmed that there may be an issue with the amp sending 5v's down the RCA ground, apparently this has happened on one unit in the past.
This would explain why it worked in the shop and not in the car since they use split grounds / transformers in the shop.

Back to the shop it goes again!