Sub keeps losing power - HELP?

[CarAudioMk2]

Hi all,

I have a VW Golf (Rabbit in the US) Mk5 with an "RCD510" stereo.

Last summer I fitted a Fli FU10 Active sub in my boot (trunk);

It's not the most powerful, or the best by any stretch, but I wasn't after blowing people's windows in, or going deaf, I just wanted a little bit of extra bass to my music. I went for this sub as it was cheap and it was small enough to not be too intrusive in my boot.

I'd fitted three or four subs and amps in the past so I did this one all myself too. Only this time I had to take the audio from the headunit from a line-out converter due to my stock HU, whereas in the past I've always used aftermarket head units so just used the RCA outputs.

Anyway, to cut to the chase...

I keep losing power intermittently to the active sub!

When I say intermittently, it can happen when the car is stopped, or in motion, and can happen over and over within the space of one song. The little green power light on the amp goes on/off/on/off etc...

I've checked the cables are all in tight enough on my sub, and that's not the issue. I've also checked the 12V cable is secured properly to the battery and the EARTH/NEG to an earth point.

So now I have the task of finding out what it actually is!

My first port of call will be the REM cable, because it's the most fragile wire of all the ones I've run through the car. If it's not that I'm going to have to start over...

Questions:

1 - What is the BEST cable to use as REM cable? (you can talk gauges and specs and I probably wouldn't know the difference, so a link would be helpful!)

2 - Is there anything else that is screaming out to you at the minute "WHY HASN'T HE CHECKED THAT?"

3 - If it isn't the REM cable, is there any way I can test the other cables for signal/power without completely rewiring?

Thanks a lot!

Click to read more...

 

[MrSlaybury]

Hey from the US.

A REM wire is purely used to signal the amp to turn on, that's it. Usually a 16-18 gauge wire is what I've seen used. I don't have any specific link for you, but what I would do is just buy a specific REM wire from a trusted seller. If you're worried about the wire being fragile, I would imagine you could use a thicker gauge (although I've personally never tried that).

I would check and recheck and triple check and then have your dog/cat/pet check your ground. It sounds like you know what's up, but make sure your grounding point is BARE metal, no paint etc.

You could use a Multimeter to test a few different things, but it really sounds like an issue with your REM. I would test your voltage at the REM wire on the amp end and make sure it's consistent with your battery's voltage. I've seen people route REM wire through area that have moving parts (like a seat folding down or even a door closing on the wire), and that had similar effects.

Did the system work at all in the past?

What brand and type of LOC are you using?

If everything worked fine in the past and now it isn't, it could be a loose connection.

A DMM has been my best friend I'm so many situations. If you don't have one, definitely buy one. You'll need it to test voltage.

I wouldn't call myself an expert on this stuff by no means, but I thought I'd share at least what I know. Sonix Electronics has some awesome articles and even videos teaching you how to trouble shoot your gear. Cheers!

 

[CarAudioMk2]

Thanks a lot for your reply. I've not got round to washing my car yet, never mind sorting the sub out! lol, but I'll check out the ground cable first, then the remote.

Out of interest, do you know what the UK equivalent to 16AWG wire is?

I'm a little concerned that if it is the remote cable, it must be me that damaged it when installing, pulling it through the car.

If that's the case I'd rather replace it with something slightly thicker and more durable.

What wire do you recommend?

Thanks!

 

[Zero_Ohms]

A digital multi meter will be you best friend. Use it to check power and remote wire with the ground you used and then check it using a different ground point. And as stated above check the ground connection. Make sure paint has been removed and make sure it is tight along with all other connections. Make sure all the wires are in the amp and no bare wires are sticking out and contacting anything. Check fuses too. I've seen them with a loose contact point inside the fuse that can cause behavior like this because the vibrations from driving can cause the connection to connect/disconnect. Also don't forget to check the connection of the remote wire on the other end where it connects to your head unit.

Sent from my stone tablet

 

[CarAudioMk2]

Thanks for that; you've given me a lot of good points to go and check now.

I've not got round to doing it all yet, but I have bought a multi-meter.

Only issue is there are that many settings on the dial on it, I'm stumped as to how exactly I should use it?

I'll check the fuse and the ground/paint issue you raised as well.

Thanks again.

 

[shizzzon 10+ year member]

16awg = 1.3mm2

 

[CarAudioMk2]

Okay, I've finally bought a multimeter and today I've done some testing.

- My 12V from battery is fine, shows 12V at all times. (The fuse seemed tight in the holder and even when I tried to wiggle it the power at the other end was 12V)

- My remote cable sends 12v from the head unit ignition port.

- My ground cable is fine, works with both the 12V and remote.

** When the 12V and ground are connected to the sub, but the remote isn't, I get 12V across the 12V & Gnd...HOWEVER, when I turn on the remote cable... that figure across the 12V & Gnd drops to 5V (and on another test 1.5V) Seemed very odd, but is this odd, or something to do with the power being drawn within the amp/sub when rem is on?).

**There's a 20A fuse in the back of the sub itself (which is fully in tact)...

This fuse is in so tight, I can only get it out with pliers...

When I took out the fuse and tested from one side of the broken fuse circuit to the ground, I got 12V, but when I tested the other side of the connection I got 12V also!!! (And 1V on another test).

Sounds to me as if there's a problem with the sub itself, but I'd hate to think I'm missing something glaringly obvious....am I?

I don't know enough about the internals of the active sub to know how it works, but throughout all tests, despite the 12V, Rem & Gnd cables being absolutely fine, the "POWER" LED in the sub never came on once, and the sub didn't work at all.

Any further advice appreciated please!

 

[loudenuff]

Okay, I've finally bought a multimeter and today I've done some testing.
- My 12V from battery is fine, shows 12V at all times. (The fuse seemed tight in the holder and even when I tried to wiggle it the power at the other end was 12V)

- My remote cable sends 12v from the head unit ignition port.

- My ground cable is fine, works with both the 12V and remote.

** When the 12V and ground are connected to the sub, but the remote isn't, I get 12V across the 12V & Gnd...HOWEVER, when I turn on the remote cable... that figure across the 12V & Gnd drops to 5V (and on another test 1.5V) Seemed very odd, but is this odd, or something to do with the power being drawn within the amp/sub when rem is on?).

**There's a 20A fuse in the back of the sub itself (which is fully in tact)...

This fuse is in so tight, I can only get it out with pliers...

When I took out the fuse and tested from one side of the broken fuse circuit to the ground, I got 12V, but when I tested the other side of the connection I got 12V also!!! (And 1V on another test).

Sounds to me as if there's a problem with the sub itself, but I'd hate to think I'm missing something glaringly obvious....am I?

I don't know enough about the internals of the active sub to know how it works, but throughout all tests, despite the 12V, Rem & Gnd cables being absolutely fine, the "POWER" LED in the sub never came on once, and the sub didn't work at all.

Any further advice appreciated please!

There must be a problem in the amplifier it that only happens when your remote wire is on. I've never heard of such a problem before though

 

[CarAudioMk2]

I'm convinced now that there's something wrong with the amp, and nothing else.

I might try to get a new amp and feed the wires from the sub through the enclosure, this will at least salvage the sub.

The unit puts out 250W RMS at 4 ohms at present, and I'm guessing it's monoblock as there's only one sub?

Can anyone recommend a replacement amp in the UK?