Okay, I know this has been posted loads before, but cant seem to find an explaination or remedy amongst the numerous posts I have read.

I fitted a sound system to my S but still retained the head unit, (as I was wrongly informed that I could not get an after-market head unit that could incorporate the in-dash controls).
Everything went well until I tried to turn the volume up

 

Not sure of your setup, but if you have a standard OEM head unit, and no separate amp, then turning up the volume will increase the current draw for the head unit significantly.

You would have to have an after market amp driven by the head unit's line-out connections (does the OEM head even have any?) to NOT increase the load on the acc power line (that's assuming that you've done the sensible thing and drawn power for the amp directly from the battery, or at worst a new connection from the fuse box).

Sounds to me like you could have a faulty head unit.

As for the fuse remover - it should be in the fuse box. RTFM to find it's exact hiding place.

 

Yep, I fitted an after market amp wired direct to the battery. Used RCA converters to get the signal to the amp. So would I be right in assuming that since I am merely using RCA converters to the amp, that is where the problem is?

 

Didn't even know the head unit had line-out connections (mine's collecting dust in the attic) !

Sounds like your setup is fine to me.

Did you have the issue before connecting up the amp ?

I've only got two thoughts, both clutching at straws.

One is poor earthing on the amp - if the connection to earth via the RCA line connectors is 'better' than the proper power earth, you might get a problem.

The other is whether the impedance on the head unit output and amp input match. Some amps allow you to feed them the speaker output from a head unit (in case you don't have RCA type line-out connections). This is a low impedance input.

If the input on the amp was low impedance, and the head unit output high, then the head unit might get upset trying to drive the outputs (a low impedance input will draw more current).

 

Opps, I think i explained it wrong, the stereo doesnt have line-outs, I converted the speeker feeds into RCA via RCA converters as the amp I am using only accepts input from RCA's. The earth to the amp is a good one, so that should be that problem out, I am not sure about the impedance on the units, I shall have to look into that one, it just seems crazy as in my head, the only thing i have altered with the head unit is to make the output go to an amp, instead of speakers, so I would not have thought this wiuld have effected the headunit in any way...the madness of electricity....

 

I'd find out what else is on that circuit if I were you. I think the fuse is obviously underrated. As Steve points out your drawing more amperage now. Have a look in the handbook find else what else is on the circuit, do a rough calc, and up the fuse little by little, until its stable. As its a low output from H/U to Amp, your going to need to crank it a lot higher to give the amp sufficient gain, from my experience. When its pushing at this unfamiliar volume level the fuse would pop I reckon. Secondly you may have an impedance mismatch in which case your generating a lot of heat, so feel the H/U or the amp ( if poorly earthed will heat also)
Disconnect speakers,turn H/U on and turn up again. Does it blow?
Let us know how you get on.
JCP

 

Many thanks, I will play about tonight once I have managed to find a shop that sells the right fuses, as my local motorist shop didnt sell the little fuses.

 

I'd put my money on those being the cause - the impedance is probably too low.

Time for an Alpine head unit and KCE865 methinks!

 

I think this is a bit risky. The fuse is probably blowing for a good reason - ie the head unit is drawing too much current. If you up the fuse, one of two things is going to happen, the head unit will go pop, or the cable will catch fire. If you had a head unit which drew a lot more power, and you replaced the cabling back to the fusebox, fair enough, but this is the standard unit, and I'm sure the fuse is set to a sensible value.

 

O.k, don't go mental with upping the amperage. Like I said go little by little (5a) if its still going pop then fault find elsewhere. The loom is good for 30 amps or there abouts but be careful. I think its on 15a std?