# RCA Melted - Boneheaded mistake?



## naiku (May 28, 2008)

A few minutes ago I went to move a couple things in my trunk, and noticed that the RCA coming from my sub amp was melted completely. To the point that all the RCA's near it on the MS8 have some scorch marks, the MS8 has some scorch marks and some plastic in the trunk has melted marks on it. 

Once that shock wore off, I pulled the molten mess out and made sure everything turned back on. Thankfully it did. Next thing I did was to remove the remote wire from the sub amp to make sure that did not power on again.

But, what caused the RCA to melt? The only thing I can think of, and this is where the boneheaded mistake came in, is that my subwoofer is currently out of the car. I removed it Friday and so since then the speaker wire is just hanging there in the trunk. Is it possible that somehow caused a short or something? I was last in the trunk Thursday and the RCA was fine then, but the sub was also still connected. I have though removed the amp to check another amp, but am certain all the wiring is still fine.

Amps are grounded via a distribution block, 8 gauge to the block, then 4 gauge to a bare metal piece in the car. What should I be checking to make sure this does not happen again? Just make sure the grounds are good? don't leave an amp powered with speaker wire hanging in the trunk?

Thanks.


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## ImK'ed (Aug 12, 2013)

I dont think a shorted speaker wire would cause this, to me it sounds like your sub amp is trying to ground through the rcas, possibly a poor ground i would double check your ground or even move it


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## naiku (May 28, 2008)

I think you might be right, I may have knocked the ground while swapping/testing amps around. Going to leave it disconnected for now until I finish my sub and think I will then spend a bit of time making sure all the grounds are good and do some general wiring clean up.


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## jb4674 (Jan 29, 2015)

Pics?


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## goodstuff (Jan 9, 2008)

Yes pics please. Never heard of it/


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## naiku (May 28, 2008)

Not much to see, if I remember I will pull the RCA out of the trash. But just picture all the RCA plastic shielding melted around the wiring inside of it and some of it charred.


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## sirbOOm (Jan 24, 2013)

Amps will usually just cut out if the speaker wire shorts... turn off for a second, turn back on see if the short is gone, turn off it it's still there, cycle, cycle.

Check ground to MS-8, too.


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## ImK'ed (Aug 12, 2013)

Yeh chances are it tried to use the ms8s ground but if you used 8 gauge ground on ms8 you may be ok. But if ground was knocked out then definetley thats the fault


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## gumbeelee (Jan 3, 2011)

It is definately a ground issue, my buddy had this happen a few years ago, that was the first time i ever seen it happen, and this is the first time since then i have heard of it...check your grounds immediately, or chances are it could happen again


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## naiku (May 28, 2008)

gumbeelee said:


> It is definately a ground issue, my buddy had this happen a few years ago, that was the first time i ever seen it happen, and this is the first time since then i have heard of it.


When I was searching Google last night I think I only came across about half a dozen results that were actually valid, to be honest I was somewhat surprised at how few there were.

Once I get home today I don't have to drive anywhere again until Friday, so will be giving all the connections a good check. Leaning towards it being the ground getting pulled or something while swapping amps around. Just wish I had a/c in the garage, Virginia humidity sucks as I am sure you are well aware.


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## gumbeelee (Jan 3, 2011)

naiku said:


> When I was searching Google last night I think I only came across about half a dozen results that were actually valid, to be honest I was somewhat surprised at how few there were.
> 
> Once I get home today I don't have to drive anywhere again until Friday, so will be giving all the connections a good check. Leaning towards it being the ground getting pulled or something while swapping amps around. Just wish I had a/c in the garage, Virginia humidity sucks as I am sure you are well aware.


Absolutely, second the va humidity it is absolutely awlful. Yeah i would about guarantee its the ground, let me know what u find out, not an issue you hear about much.


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## jb4674 (Jan 29, 2015)

It's been kinda cool over here in Northern VA today.


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## naiku (May 28, 2008)

jb4674 said:


> It's been kinda cool over here in Northern VA today.


Where are you located? You should head out to the VA BBQ meet on the 20th.

Was a bit cooler today, so I checked the grounds. Both ends appeared fine. I have 8ga from the amp, to a 3 way distribution block, then 4ga to a metal piece in the car. Just to be sure I undid the ground screw on both ends and made sure the cable was in securely. 

Everything looks fine to me, is there anything else I can check? The amp is still disconnected, no sub currently, but I want to be sure this won't happen again.


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## Victor_inox (Apr 27, 2012)

RCA ground act like one when main ground lost, therefore overheating and melted, end of story.


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## naiku (May 28, 2008)

Well crap, 3 months later and it did it again. What's really odd is I have done nothing with the system since last time it happened and it's been working fine. 

Went out at lunchtime, nothing wrong, driving home from work noticed my sub was not working. Pulled carpet back in trunk when I got home, melted wires. Has me worried to be honest, will get some pics later when I start pulling stuff out. I am using a block on my grounds, but as far as I know that should be no issue.


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## naiku (May 28, 2008)

Pics...


















The first pic is where the rca's melted together, not sure which caused it though. Second is melted plastic on the trunk floor. The little black looking pieces are soot, I assume from the rca's sparking as they melted against each other and the plastic.

At first glance the grounds appear sound, 3 day weekend so I am going to remove and reinstall them though as something is clearly wrong.


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## naiku (May 28, 2008)

It's the sub amp again, what's weird is the ground feels good in the block. The only thing I can think of is that the MS8 ground is in the same opening, which is possibly carding the sub amps ground to not be good enough. 

Going to relocate the MS8 ground and reposition the ground distribution block. Fingers crossed that fixes it permanently.


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## gumbeelee (Jan 3, 2011)

Were you using the same ground for everything? Nevermind i see u r using a block! I would try what u suggested and see what happens. I actually remember commenting on this the first time it happened to you. Hope u figure it out.


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## XSIV SPL (Jun 24, 2014)

Very odd, indeed, but something about your equipment/installation is making this RCA cable the path of least resistance, and at amperage levels sufficient to melt things without blowing a breaker or fuse, which should be very concerning to you. You probably have a car fire just waiting to happen here.

If this were my own situation, I would immediately disconnect power from the system, get out a multimeter and search for the cause, which is either a faulty piece of hardware or a problem with the installation wiring.

I'm pretty amazed that you've been dealing with this since May and haven't taken more serious remedial action.


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## naiku (May 28, 2008)

XSIV SPL said:


> If this were my own situation, I would immediately disconnect power from the system, get out a multimeter and search for the cause, which is either a faulty piece of hardware or a problem with the installation wiring.
> 
> I'm pretty amazed that you've been dealing with this since May and haven't taken more serious remedial action.


While it first happened in May, after checking grounds back then, I ran it for a while with the trunk not put back together. None of the RCA's got even warm to the touch so I figured it was resolved. 

It is a huge worry to me, and causes me a great deal of concern since i realize how serious it can be. Can you let me know what I should be checking with a multimeter? I can visually inspect the wiring, but not sure what I would even check with a meter. Thanks.


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## naiku (May 28, 2008)

OK, so I relocated the MS8 ground, swapped the 8 gauge ground on the A5001 to 4 gauge. I also measured the resistance using a meter and got a reading of between 0.03 and 0.01 (same on all amps). So I reconnect everything and as I am putting the amp back in its usual location notice a spark jump from the amp cover to a piece of metal in the trunk.

Disconnected the battery and checked everything again, no issues. Try to re-create the spark with a piece of wire between the amp case and the trunk, no sparks, try measuring with the DMM and get nothing on the case. Reconnected the battery, amp powers on initially (I think when reconnecting battery, it causes the MS8 to power on briefly, which powers on the amps). Everything switches off, not more than 10 seconds later I smell burning, immediately yank the now melted RCA from both the MS8 and A5001. 

Disconnected the battery again and removed the amp, tried again with nothing else plugged in (No other amps, only the 1 RCA to the A5001) and it melts again. Ground still measures fine.

At this point I am stuck as to what else to try. If the MS8 had a poor ground, could this potentially try grounding out through the RCA to the A5001? I am using 12 gauge for the MS8 ground, to the same spot the amps are grounded at. If it was an MS8 problem though why does it only affect the one amp? I also reconnected the battery after removing the A5001 and left it for a few minutes, none of the other RCA's get warm at all, much less able to melt them entirely in seconds. 99.9% sure it's something with the amplifier, I just have no idea what. 

So, I have the battery still disconnected. Removed the A5001 entirely for now


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## gumbeelee (Jan 3, 2011)

naiku said:


> OK, so I relocated the MS8 ground, swapped the 8 gauge ground on the A5001 to 4 gauge. I also measured the resistance using a meter and got a reading of between 0.03 and 0.01 (same on all amps). So I reconnect everything and as I am putting the amp back in its usual location notice a spark jump from the amp cover to a piece of metal in the trunk.
> 
> Disconnected the battery and checked everything again, no issues. Try to re-create the spark with a piece of wire between the amp case and the trunk, no sparks, try measuring with the DMM and get nothing on the case. Reconnected the battery, amp powers on initially (I think when reconnecting battery, it causes the MS8 to power on briefly, which powers on the amps). Everything switches off, not more than 10 seconds later I smell burning, immediately yank the now melted RCA from both the MS8 and A5001.
> 
> ...



If it were me at this point and u didn't know what to do next i would just take it on to my local car audio shop. Let them diagnose the problem and fix it. Don't won't your car to be the next thing to "melt down"


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## naiku (May 28, 2008)

gumbeelee said:


> If it were me at this point and u didn't know what to do next i would just take it on to my local car audio shop. Let them diagnose the problem and fix it. Don't won't your car to be the next thing to "melt down"


Exactly my thinking, going to see if I can find someone more experienced locally or take it to a shop. Going to test one more thing on the amp later and then put the car back together with the amp out of the equation.


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## seafish (Aug 1, 2012)

gumbeelee said:


> If it were me at this point and u didn't know what to do next i would just take it on to my local car audio shop. Let them diagnose the problem and fix it. Don't won't your car to be the next thing to "melt down"


That IS assuming that your local car stereo shop is a reputable shop with honest experts who don't simply want to sell you another amp. They are out there, but IMO they are also the rare bird.


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## naiku (May 28, 2008)

seafish said:


> That IS assuming that your local car stereo shop is a reputable shop with honest experts who don't simply want to sell you another amp. They are out there, but IMO they are also the rare bird.


So true. Partly why I am hoping to find a knowledgeable local member! Just yesterday I was in a shop and was laughing to myself as I overheard a salesman giving it the full speech to someone about speakers.


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## cajunner (Apr 13, 2007)

sounds to me like you have a body part that appears to be well-grounded but isn't.

You keep testing the ground and it measures fine, but maybe that's because it's taking the ground path that is there, like an RCA cord and not the one that you want, through the body of the car back to the battery.

Have you had any body work done to the car? If there's a factory ground strap that wasn't replaced properly or got loose that could cause you some headache.

I would also like to know what you are measuring when you say the ground measures those low figures, are you comparing the difference between poles of the battery (resting voltage) and the rest of the circuit that involves your install?


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## naiku (May 28, 2008)

No body work done to the car at all. 

I am measuring from amps ground terminal to the distribution block to get those readings. If that's not a good test, what else should I measure? Should I also measure from ground point in trunk to battery? 

The odd thing is that it only affects the one amp, the other 2 and the ms8 are functioning fine.


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## naiku (May 28, 2008)

Doing some reading last night I found a couple threads of people with similar problems:
RCA wire meltdown!! - Page 2 - Amplifiers - SMD Forum

12volts]12volts on my amp's RCA inputs [Archive] - AudioBanter on my amp's RCA inputs [Archive] - AudioBanter

If I set my DMM to check for continuity, put one probe on the RCA ground and the other on the 12v input of the amp, it beeps constantly. Does that mean when I have power to the amp, it is then putting 12v out through the RCA? If so then I guess that's my problem. 

If that is it, what would cause that? If it turns out to be the amp, I at least think it's still under warranty.


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## seafish (Aug 1, 2012)

naiku said:


> Doing some reading last night I found a couple threads of people with similar problems:
> RCA wire meltdown!! - Page 2 - Amplifiers - SMD Forum
> 
> 12volts]12volts on my amp's RCA inputs [Archive] - AudioBanter on my amp's RCA inputs [Archive] - AudioBanter
> ...


Yes. the beep indicates continuity, which obviously should NOT be there between the RCA ground and 12v input. I have been thinking a lll along that it is something internal to the amp…that being said, look CAREFULLY at your 12 v input and ground to the amp just to make sure that it is not something super simple. 

If the amp is under warranty, I would send it in.


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## Hanatsu (Nov 9, 2010)

If your ground is ok it sounds to me that amp is shorted internally, I'd disconnect it immediately before you melt something worse than the RCA cables.


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## naiku (May 28, 2008)

seafish said:


> look CAREFULLY at your 12 v input and ground to the amp just to make sure that it is not something super simple.


Anything specific I should look at? The DMM indicates continuity with it fully disconnected from the car, as in sitting on my desk. No power to it. I have replaced the ground twice, it's in a good spot and no other equipment has any problems. I also swapped out the 12v cable while checking grounds last week, it's 4 gauge to a distro, then 8 gauge into the amp. 

The thing that kind of sucks, is that while this is looking more and more like an amplifier problem. I am slightly nervous about powering anything back up in the car, I have my kids in there, and while I have had no issues with any previous amps or the processor. It's still in the back of my head that there was a fire hazard behind them 



Hanatsu said:


> If your ground is ok it sounds to me that amp is shorted internally, I'd disconnect it immediately before you melt something worse than the RCA cables.


It has been removed from the car since Friday evening, I had it connected back up once or twice while trouble shooting. But it's no longer in the car.


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## Hillbilly SQ (Jan 26, 2007)

Reading through your troubleshooting, I can promise you it's the amp. 11 years ago I had an Eclipse pa32440 that was sending an arc through the rca cables. On really close inspection I found a sloppy solder joint shorting something out. It's been over a decade so memory is a little fuzzy on the details. If you quit having problems after removing that amps I think it's time to either send it in for warranty or look into buying a new amp.


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## naiku (May 28, 2008)

Hillbilly SQ said:


> Reading through your troubleshooting, I can promise you it's the amp. 11 years ago I had an Eclipse pa32440 that was sending an arc through the rca cables. On really close inspection I found a sloppy solder joint shorting something out. It's been over a decade so memory is a little fuzzy on the details. If you quit having problems after removing that amps I think it's time to either send it in for warranty or look into buying a new amp.


Thanks, the amp is only about 4 months old so sorting out a warranty replacement now. 

What sucks is that it burned through about $50 worth of RCA cables, melted a hole in my trunk floor and should I ever try to sell my MS8 it looks burned due to scorch marks on it, meaning it will be a tough sell despite having nothing wrong with it. 

Thankfully it was just some electronic equipment though and not anything worse.


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## Hillbilly SQ (Jan 26, 2007)

Yeah you and your kids got lucky on this one I think. For sure don't want to be "that car we've all seen at one time or another" on the side of the road with smoke rolling out of it. If you like the MS-8 you may as well run it until it decides it's time to close the lid on itself. That's how I've gotten with amps and processors lately. Speakers otoh...


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## naiku (May 28, 2008)

Thankfully I am happy with the MS8, so resell value/difficulty is not much of an issue. But, as I am sure you well know, sometimes you just want to try something new!


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