AMP QUESTION

[DEMONKNIGHT666]

Hi all,

Alpine 9856 RCA to JL AUDIO 2150 Monobloc Amp powering MTX Sledghammer Sub.
Been working for an age until my Ground worked its way loose and I lost all Bass.

Checked the Remote which still switches Amp off and on fron HU.
Big problem though Power light on Amp stays on when Ground wasn't connected, did a search and seems I've blown the RCA board on the HU.

The JL audio amp has High Level input molex for splicing in speaker connections (from Rear),
I don't have the correct molex connector so made one from bullet connectors, but still no output from Amp to Sub.
Any help please.

 

[wozzaa]

Daft question..have you checked the fuses if it has one?

Normally if the ground comes out nothing really happens it just stops working until you hook it up again. Can't see it blowing the RCA's doing that. Typically only happens when you start plugging them in and out when everything is on and playing.

 

[Dink]

you getting an output from the hu? as you could of cooked some traces in the hu

i'd say the rca board contains all the setting components so i doubt the high level will work

 

[wozzaa]

you getting an output from the hu? as you could of cooked some traces in the hu

i'd say the rca board contains all the setting components so i doubt the high level will work

Then he would have no output at all, not just a loss of bass. From what he described he has only lost the subwoofer after the ground on the amp came out.

 

[DEMONKNIGHT666]

Daft question..have you checked the fuses if it has one?

Normally if the ground comes out nothing really happens it just stops working until you hook it up again. Can't see it blowing the RCA's doing that. Typically only happens when you start plugging them in and out when everything is on and playing.

HU works as normal to Fronts and Rears, not amped.
Green Power light on Amp and switches with HU on and off.
Nope, I've done nothing silly like that, it's weird.

 

[DEMONKNIGHT666]

you getting an output from the hu? as you could of cooked some traces in the hu

i'd say the rca board contains all the setting components so i doubt the high level will work

HU working apart from throwing Bass on the RCA's to amp.
It's suggested at my local Car Stereo shop that I've fried the RCA's on the HU, the amp is bullet proof or so they say.
I'm connecting to the High Levels on the amp with no RCA's connected and still nothing.

 

[DEMONKNIGHT666]

Think I need to throw another RCA input to the amp to check the Sub is still intact.

 

[Dink]

Then he would have no output at all, not just a loss of bass. From what he described he has only lost the subwoofer after the ground on the amp came out.

i meant to say output from the hu down the rcas

i'd say the sub itself would be fine.

i'd say you have have cooked the pcb in the amp as it would of tried to find a ground once the main one was disconnected and tried the one on the rca's

thats also why it could of taken the rca output of your hu with it

 

[DEMONKNIGHT666]

Got you, I have another AMP and that doesn't work either, exact same scenerio, HU remote switchs Amp on and and off but nothing when RCA's or High level input connected.
so, RCA on Amp and HU blown and could have taken the High level input on the amp as well but doesn't explain 2nd Amp not working through High Level input.

 

[Dink]

did you have the rcas plugged in on the second amp you tried?

 

[DEMONKNIGHT666]

did you have the rcas plugged in on the second amp you tried?

Yes, no sound.

 

[Dink]

im meant at the same time as the high level?

 

[DEMONKNIGHT666]

im meant at the same time as the high level?

Nope, checked them separately.

 

[Dink]

did you try the rca input off another source (mp3 player/phone 3.5mm output)?

you can try with a 1.5v battery on the lead to the sub to see if you have a circuit

i really don't think the sub would of been damaged at all

one other thing is you might of cooked your rca's aswell as the large current could of melted the thin leads

 

[wozzaa]

I just find it hard to believe that an earth cable coming lose on a JL amp would take out everything else. They don't exactly build crappy amps.

Also wouldn't it have just turned off or gone into protect. The fact he can't get high level or RCA out put from the amp yet his speakers are working to me says the amp or sub is more likely to be the problem.

 

[Dink]

I just find it hard to believe that an earth cable coming lose on a JL amp would take out everything else. They don't exactly build crappy amps.

Also wouldn't it have just turned off or gone into protect. The fact he can't get high level or RCA out put from the amp yet his speakers are working to me says the amp or sub is more likely to be the problem.

oh yeah there not crap amps (i've got a 6 year old one that still works) but they probably still have to join all the grounds together inside to make sure they get the best sound quality

yeah the amp is most probably at fault but the rca output from the hu is seperate the amplified output to the speakers

 

[DEMONKNIGHT666]

yep those Amps are bullet proof, so it's more than likely the RCA circuit on the HU has blown, I'll try and put another RCA feed into the Amp and see what I get, if it works I will know it's the HU.
The HU is working fine apart from no output to the Sub, all my other speakers are working fine.

 

[DEMONKNIGHT666]

Tried 2 different RCA inputs on the both amps and still no Sound, Hooked up the sub to different Amp and that works.
Tried the High level inputs on both amps and no sound.
So looks like I've blown RCA and High level on both Amps, still not sure if I've blown the RCA output on the HU.
I used a different RCA lead to test with other systems.

 

[DEMONKNIGHT666]

Well, I tried the Amp in a different car and it worked so after measuring the Voltage coming into the Amp found is was enough to power the Green on light but not enough to amplify the sound so I installed a power cap and viola working fine, no blown RCAs no Blown Hu just a flaky battery that's on it's way out. amazing.