why oh why?????

[cxcxcxvcvcvc]

ok as some know i had a problem with my fusion jonah lomu d class amp a few months back, well i sent it to fusion and they repaired it for free outside of its warranty(champs) well today the amp has blown again when i dropped my son off for school the amp was working fine (subs running) and then all of a sudden the subs just stopped...! i was not even cranking the subs! so as soon as i noticed subs werent running i turned the amp off, and after getting home did a test with my multi, checked all power cables fuses, earths and just like before i cannot see what has cause this to happen i have a 4 channel amp running of the same power supply and that amp is working fine!
i cannot believe this!!aarrrggghhhh!!!! for $1500 for this amp when new you would think it would be a hell of alot more stable than this!!!! and i can just bet that fusion wont be fixing it again for free this time round the last time they reapaired it they said that it had blown some resistors? i dont care anymore im getting sick of this pitcure sorry for the rant fellas just had enough....

[88GreenVN]

Get it off ya chest there fella.... It does help.

It may not cost all that much to fix - a few resistors at Dick Smiths & a bit of solder.

[cxcxcxvcvcvc]

Get it off ya chest there fella.... It does help.

It may not cost all that much to fix - a few resistors at Dick Smiths & a bit of solder.

cheers mate!
yeah, well i rang up fusion and told them whats the go , and they said they are going to send out a rep to have a look @ the car to determine whats going on! i said that i would like nothing more than that! the bloke on the phone said, that even though the resistors where replaced last time on the amp, that still the underlying fault in the amp may not have been fixed! so maybe just maybe when the guy from fusion comes out and after looking @ the car (if he can find nothing wrong) then the amp might get fixed for free again! but he wont be out for about a week the guy said as he,s down in sydney @ fusion,s head quarters ect! but at least theres a little light at the end of the tunnel

[impulsesv6]

could be worth while popping into a totally indepentant audio shop just to make sure 100% that it isnt caused by install - cos if they want to be sneaky thats what they will blame it on.

then if they do blame it on install just say that ................car audio shop says it aint.

[cxcxcxvcvcvc]

could be worth while popping into a totally indepentant audio shop just to make sure 100% that it isnt caused by install - cos if they want to be sneaky thats what they will blame it on.

then if they do blame it on install just say that ................car audio shop says it aint.

yeah i might do that, but ive already pulled the amp! i will be going through the car today with a comb to make sure everything is in order honestly though im not worried about my install, i know i have installed everything the right way and double checked everything, in fact when i got the amp back from fusion i pulled the head deck out of the car, the eq, and ran better wireing to the amp cheked all connections ect because i wanted to be sure and have peace of mind & didnt want this to happen i spose even though you make precautions these things can still happen well its really up to fusion now!

[Adelaideprosound]

Where is the earth placed for the amp?

[cxcxcxvcvcvc]

Where is the earth placed for the amp?

on the rear wheel arch! i have stripped the paint back to bare metal and put a gold plated earth connection on the rear wheel arch!
i have also tested the amp with a multi @ its inputs and theres plenty of current there!

[Joe Peeps]

Sorry to hear about your dramas mate, that must be incredibly frustrating especially when you know your install is up to scratch... Hopefully it turns out ok for you buddy.

Where is the earth placed for the amp?

Where would you recommend in a VS APS? The wheel arch as used here? Baby seat bolt?

[cxcxcxvcvcvc]

Sorry to hear about your dramas mate, that must be incredibly frustrating especially when you know your install is up to scratch... Hopefully it turns out ok for you buddy.



Where would you recommend in a VS APS? The wheel arch as used here? Baby seat bolt?

yeah cheers mate! will have to wait another week before this guy comes out, then i will have to wait about another month and a half to get it sent back to fusion to get it reapaired

[Adelaideprosound]

Well a VS is a monocoque chassis which means the car has chassis rails which end underneath the front seat and the rest of the shell is supported by sheet metal which is spot welded in certain spots so that it supports the structural integrity of the car but so that if the car were in an accident it will crumble around the cabin minimising damage to its occupants. Well this is the general idea anyway.

Also the main chassis rails are held onto the shell with 4 main bolts. This makes the monocoque chassis a prick of a thing when it comes to earthing.

Has anyone measured the resistance back to the negative of the battery from a Commodore, any commodore VN onwards. You come up with about 7.5 to 8 ohms resistance which is wayyy to high. The return path for an amplifier thru a vehicle chassis should be less than 0.2 of an ohm.

So the best position to earth an amplifier in a VS is under the rear seat or as close to the main chassis rail under the front seat where the sheet metal doubles.

The baby seat bolt, parcel shelf, wheel arch any of that area is not a good earth because it is only supported by spot welds.

Also with Commodores the best way to install an amplifier is to do an earthing kit under the bonnet, upgrade the charge wire to 4 gauge from the alternator, and also run a 0 gauge earth from the negative of the battery to under the front seat secure with a bolt under the front seat where the sheet metal is double, and then run the rest of the 0 gauge to the back where the amplifier is earthed. This reduces the resistance and gives the amplifier an alternate return path for ground should the chassis be weak which in a Commodores case it is.

You will find a lot of Pioneer headunits fail in Commodores where people run amplifiers due to the amplifiers trying to find the closest earth appart from the main earth point and it goes thru the RCA's and can blow the internal noise shield fuse which protects the RCA's or as some people call it IT CAN BLOW THE EARTH TRACKS. These are only capable of withstanding about 1-2 amps of current any more and the fuse will blow possibly taking one of the tracks out with it.

So sorry about the long winded reply but this is the jist of why amplifiers fail in Commodores GENERALLY, unless of course it is entirely a product failure. In two years of running my business i had one amp come back the other which happened to be a Commodore where the customer didnt want to pay for an earthing kit but was recommended to do so. We measured the resistance to prove to him as to why the amplifier failed and once he saw the 6 ohm resistance measurement he understood what i was talking about at the beginning.

[Joe Peeps]

Wow... helluva post mate! So guys like the OP and myself running big amps:

are better off running say, 0 or even 2x0 to the front seat rail bolts From the amp as opposed to the theory keep your earths short... i thought about return wires but already have 2x0 power through the wall and the cost of cable is $$$.

Sorry for the hijack but i feel this q is related i hope you dont mind cxcxcxcvcvc!

[Adelaideprosound]

No no, what i meant was if your amps are mounted in the boot, you would earth them as close as possible to the amp under the rear seat. Then from the battery negative you run a 0 or even 2x0 gauge runs under the front seat, split them and bolt them under there to where the chassis rail ends, and then run another set to under the rear seat to where the amplifier is bolted to.

I hope this makes it clearer man, it is to improve to weak transfer thru the spot welds so the amplifier has extra room to breathe via the 0 gauge if any heavy current demands are needed with big bass hits and stuff.

So earth as close as possible to the amp on the floor pan not under the parcel shelf or wheel arches these are no good, they are only spot welded. Earth on the floor pan under the rear seat and then from that point extend the earth wire with heavier gauge under the seat to a bolt and from under the seat to the negative of the battery.

There you go two explanations one from front to back and the other back to front .

[cxcxcxvcvcvc]

Well a VS is a monocoque chassis which means the car has chassis rails which end underneath the front seat and the rest of the shell is supported by sheet metal which is spot welded in certain spots so that it supports the structural integrity of the car but so that if the car were in an accident it will crumble around the cabin minimising damage to its occupants. Well this is the general idea anyway.

Also the main chassis rails are held onto the shell with 4 main bolts. This makes the monocoque chassis a prick of a thing when it comes to earthing.

Has anyone measured the resistance back to the negative of the battery from a Commodore, any commodore VN onwards. You come up with about 7.5 to 8 ohms resistance which is wayyy to high. The return path for an amplifier thru a vehicle chassis should be less than 0.2 of an ohm.

So the best position to earth an amplifier in a VS is under the rear seat or as close to the main chassis rail under the front seat where the sheet metal doubles.

The baby seat bolt, parcel shelf, wheel arch any of that area is not a good earth because it is only supported by spot welds.

Also with Commodores the best way to install an amplifier is to do an earthing kit under the bonnet, upgrade the charge wire to 4 gauge from the alternator, and also run a 0 gauge earth from the negative of the battery to under the front seat secure with a bolt under the front seat where the sheet metal is double, and then run the rest of the 0 gauge to the back where the amplifier is earthed. This reduces the resistance and gives the amplifier an alternate return path for ground should the chassis be weak which in a Commodores case it is.

You will find a lot of Pioneer headunits fail in Commodores where people run amplifiers due to the amplifiers trying to find the closest earth appart from the main earth point and it goes thru the RCA's and can blow the internal noise shield fuse which protects the RCA's or as some people call it IT CAN BLOW THE EARTH TRACKS. These are only capable of withstanding about 1-2 amps of current any more and the fuse will blow possibly taking one of the tracks out with it.

So sorry about the long winded reply but this is the jist of why amplifiers fail in Commodores GENERALLY, unless of course it is entirely a product failure. In two years of running my business i had one amp come back the other which happened to be a Commodore where the customer didnt want to pay for an earthing kit but was recommended to do so. We measured the resistance to prove to him as to why the amplifier failed and once he saw the 6 ohm resistance measurement he understood what i was talking about at the beginning.

cheers mate for all the info you have provided yeah i have a sus feeling that the amp is failing due to earth problems, and the reason you have stated is most probably why! if the amp gets repaired again from fusion i will do as you have suggested! and cheers for everyone else,s input, it has been great

[StoneX]

What model sub/s? How are the subs wired?

[edit] Found out your amp model. FJL-1611D.

[Joe Peeps]

lol ok. im with you now. Crystal clear upon reread even from the original post I'll have to get onto that one

[Adelaideprosound]

Sweet didnt want my post to be misunderstood, your amps life is at stake .

[cxcxcxvcvcvc]

What model sub/s? How are the subs wired?

[edit] Found out your amp model. FJL-1611D.

there to 12" powerplants wired to run parallel @ 2ohms? im not 100% as autobarn hooked them up for me when they were in my vl.

[StoneX]

After looking at the amp specs, it can run down to 1 ohm anyway, so I doubt it'd be caused by the subs or their wiring. It's more likely the grounding like APS referred to

[cxcxcxvcvcvc]

yeah this amp draws alot of power from the car when cranked up, so i think its dying from a weak earth as suggested!

[clyde]

ill have to get onto my earths 2morra then.....

wheel arch