Blown ground on the RCA outputs
Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=87152
Printed Date: May 03, 2024 at 6:50 PM
Topic: Blown ground on the RCA outputs
Posted By: sin0cide
Subject: Blown ground on the RCA outputs
Date Posted: December 13, 2006 at 6:30 PM
So we had this issue with a custom the other day because he was getting a bad whine from everything electrical in the car. So needless to say he took it to another shop and they said the rca ground shield was blown and we replaced the deck and it fix it. So my question is how can you blow that? The tech over at the other shop said you have to power the amp up before you plug in the rca's so that wont happen. I am confused as to what he was talking about.
Replies:
Posted By: brokeitagain
Date Posted: December 13, 2006 at 6:49 PM
what he probably meant was that you need to connect BOTH power cables to the amp before you connect the RCAs so that the amp doesnt seek a ground through the HU wich should not matter as you should ALWAYS disconnect the negative side of the battery before begining an amp install or any electrical repair or install
Posted By: sin0cide
Date Posted: December 13, 2006 at 9:10 PM
I thought the rca's would have been isolated. I take out the fuse to the power wire before I run it so there is no power going to the amp untill everything is plugged in.
Posted By: brokeitagain
Date Posted: December 13, 2006 at 9:23 PM
i always connect RCA's after ALL other amp connections. Then reconnect the battery
Posted By: sin0cide
Date Posted: December 14, 2006 at 12:30 AM
thanks broke it... I am kinda disappointed that nobody else has chimed in this seems to be a big issue.
Posted By: haemphyst
Date Posted: December 14, 2006 at 12:48 AM
This is the VERY reason you never fuse a ground... IF the fuse in the primary ground were to blow, all the ground current will try to go wherever it can to complete the circuit. This CAN include RCA cable shields as well. Inside the deck the ground traces for the RCAs are tiny indeed, and CAN be easily destroyed by this instantaneous massive current flow.
Pioneer decks are prety notorious for this "design". I personally call it a flaw, but I'm not an engineer... I just know that I have seen NUMEROUS Pioneer decks on my buddy Dave's repair bench, for JUST THIS VERY REASON!
So, kids, now we know DON'T FUSE THE GROUND CABLE!
-------------
It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."
Posted By: sin0cide
Date Posted: December 14, 2006 at 1:03 AM
I was reading somethign about that but haemphyst why the big speach about fuseing a ground cable... who would fuse a ground cable... I was talking about the fuse in the power wire...
Posted By: haemphyst
Date Posted: December 14, 2006 at 2:41 AM
sin0cide wrote:
I was reading somethign about that but haemphyst why the big speach about fuseing a ground cable... who would fuse a ground cable... I was talking about the fuse in the power wire...
People HAVE fused the ground cable... I've seen it. That's why I mentioned it. I knew what you were speaking of, and I didn't feel it was a "big speech". It was simply good information that nobody had addressed in the thread. ------------- It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."
Posted By: sin0cide
Date Posted: December 14, 2006 at 3:41 AM
I was grateful for the insight just was confused as to if I did something wrong.
Posted By: haemphyst
Date Posted: December 14, 2006 at 11:07 AM
No... as far as I could tell, you had done nothing wrong with your install... It is also entirely possible that "it just happened". Accidents and mistakes do occasionally occur, and as an accident or mistake (we all have and make them) there is no blame.
-------------
It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."
Posted By: sin0cide
Date Posted: December 14, 2006 at 1:43 PM
I did do a check on the resistance between the negative terminal of the battery and the negative terminal of the amp and got 12 ohms of resistance would that have been an issue?
Posted By: brokeitagain
Date Posted: December 15, 2006 at 12:07 AM
wow thats a huge amount of resistance,it may have not been a factor in the failure but ill bet that it didnot help
Posted By: brokeitagain
Date Posted: December 15, 2006 at 12:10 AM
BTW a voltage drop measurement done while the circuit is under a load is a much better indication of resistance than an ohm reading
|