diyAudio

diyAudio (http://www.diyaudio.com/forums/)
-   Car Audio (http://www.diyaudio.com/forums/car-audio/)
-   -   Quick question... (http://www.diyaudio.com/forums/car-audio/98807-quick-question.html)

WackiCO 25th March 2007 01:51 AM

Quick question...
 
How do you measure the volts coming through the RCA cables that feed into your amp?? Also, what should this voltage be?? I have a Pioneer Premier deck that states an output voltage of 4.5v....is that what i should be reading on the voltmeter?? Do I connect the ground from the voltmeter to the ground on the amp or on the shield that surrounds the end of the cable??

Thanks in advance for your help.

MadMutt 25th March 2007 02:02 AM

The voltage on the rca's is variable ac.
It's the music signal.
It will vary with volume setting and also what's being played by the deck.

The only way your going to measure it is either by using a test disc/tape with a continuos sine wave, or with an ocilliscope.

The 4.5v is only really a guide as to the maximum the head unit can deliver without distortion.

Why, do you think it's faulty ?

WackiCO 25th March 2007 08:00 AM

I think now that actually my head unit outputs are bad, i dont have any voltage coming through them whatsoever, any other ideas on what could be wrong??

For a while the music would cut in and out coming out of the sub, and now it is just totally silent, all input voltages are correct(remote and pwer), I checked the cable, and now all i can think of is that since there is nothing coming through the RCA the preouts on the head unit arent working....

Clipped 25th March 2007 11:15 AM

with pioneer decks its almost always mandatory to ground the rca outer shield to the deck...manufacturing defect that they havent fixed for a few production runs now...

you also have to turn off the system before pulling the rca's out of
the amp when it is plugged into the deck...only pioneer decks require this...that i know of, and have fried personally.

did you use a test tone to measure? you cant usually measure using music.

check the rca jacks ... its usually the culprit in this kind of case.

stick your meter on ohm and put each lead on the center...then put each lead on the outer...you should get something like
0.0 or 0.2 but if you get OL the cable is bad...if its the kind with a soldered and screwed on head, you can fix it.

did you check the subs? measure the ohms and look at where the tinsel leads terminate.

check the fuse on the amp too.

WackiCO 27th March 2007 03:07 PM

""with pioneer decks its almost always mandatory to ground the rca outer shield to the deck...manufacturing defect that they havent fixed for a few production runs now...""

Hmm, I am not sure exactly what you mean by this, I installed it all myself and everything worked perfectly for almost a year.

""you also have to turn off the system before pulling the rca's out of the amp when it is plugged into the deck...only pioneer decks require this...that i know of, and have fried personally.""

This I may have done, however I installed a different (pioneer) deck into the system and still had no luck, it was not even cutting out like it was at the beginning stage of this going bad.

""did you use a test tone to measure? you cant usually measure using music.""

No, i dont have any test tone cd's.

""check the rca jacks ... its usually the culprit in this kind of case.""

I have looked at them, they seem fine, but i am running out of options on what to check here. I do have anther dumb question, what is the little wire in between my RCA's for?? I have never had it connected to anything, and actually this is the first set of RCA's that I have had it on...

""stick your meter on ohm and put each lead on the center...then put each lead on the outer...you should get something like
0.0 or 0.2 but if you get OL the cable is bad...if its the kind with a soldered and screwed on head, you can fix it.""

I will test this out when i get home...

""did you check the subs? measure the ohms and look at where the tinsel leads terminate.""

I will also test this when i get home, what should the ohms be for the sub?? Also what are the tinsel leads?? I did notice that the sub seems to be causing a little friction when i push on it to move it forward and back, I was going to test the sub in a friends system to see if that is the problem.

""check the fuse on the amp too.""

The fuse is good.


From what i have done with this over the weekend, I have replaced the head unit with one that i know works, i have also replaced the amp with another one i know works, I have checked the RMT, PW, and ground cables, all ok, and I checked the output from the speaker terminals on the amp and it was sending a signal (dont remember what it read or the setting i had it on, a friend was helping me), what is the best way to check this(what do i set my meter to??)

Right now my last two options as i can see is the RCA cable is bad or the sub is bad...

Thanks very much for the input, you both have been very helpful.

Clipped 27th March 2007 04:56 PM

if you have a laptop or just a really long rca cable, you can download winisd , there is a test tone generator in this program.

and play the tone through the computer to the car stereo.
------------------------------------------------------
that wire on your rca jacks is used as an extra signal ground, for grounding to the chassis of the headunit...sometimes you need it sometimes you dont....pioneers need it.
------------------------------------------------------
the ohm for the subs depends on the impedence of the voice coils
if you have a 4 ohm coil, it usually reads somewhere around 3.7 to 4.2 ohms...somewhere inbetween.

if you have two 4 ohm coils in parrallel it should read around 1.8 to 2.2 ohms
-----------------------------------------------------------

the tinsel leads are the wires that lead from the terminal on the speaker to the voice coil....sometimes they are hanging in between and sometimes they are woven into the spider.

if they rip , you wont get any readings, if they come loose from the terminals you wont get any readings....
----------------------------------------------------------
when you push down on the speaker you have to make sure you are pressing directly down and not skewing it to one side. or else it will rub and cause that friction feeling.

if youre sure you are pushing perfectly straight down and feel friction, that meas the voice coil has become unwound...blown.
---------------------------------------------------------
i wouldnt test it in a friends system, if the coil is shorted and if his amp doesnt have protection...you coud burn his amp up.

do this instead, disconnect the sub from the amp and hook a D cell or nine volt battery to it...if it moves it probably still works...it will only move in one direction with the battery, to get it to move the other direction, reverse the wires.

eventhough it moves,it can still mean the voice coil is becoming unwound...and unsafe to use.
-----------------------------------------------------------
what kind of sub?

WackiCO 27th March 2007 05:14 PM

The sub is a Rockford Fosgate 10", I dont remember the model offhand, but its the cheap one at best buy....I think i paid somewhere around 50 or 60 bucks for it...

Another thing to note on this is that i have installed a fan because the amp kept overheating, and I wired that directly to the remote turn on and ground, so the fan is always on whenever the amp turns on, I just read >

http://www.bcae1.com/coolfans.htm

and it states that this can cause damage from the current draw of the fan...I imagine this can be a problem, however since I totally replaced this amp with a different (working) amp i doubt it...

""that wire on your rca jacks is used as an extra signal ground, for grounding to the chassis of the headunit...sometimes you need it sometimes you dont....pioneers need it.""

So i ground one end to the head unit (where??) and the other end to what?? Why is it that i did not have to do this before when it was working fine??

richie00boy 27th March 2007 05:31 PM

Quote:

Originally posted by WackiCO
I just read >

http://www.bcae1.com/coolfans.htm

and it states that this can cause damage from the current draw of the fan...I imagine this can be a problem, however since I totally replaced this amp with a different (working) amp i doubt it...

You misunderstood. It's not the amp that the fan can damage, it's the headunit. The fan takes too much out of the headunit remote output and blows it. Then the amp never gets the remote signal any more.

WackiCO 27th March 2007 05:43 PM

richie00boy,

Ahh, i see...however the fan still works and the amp powers on, so i would imagine everything is still ok, at least for the time being, right??

richie00boy 27th March 2007 06:50 PM

Ok sounds that way.


All times are GMT. The time now is 06:30 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio


Content Relevant URLs by vBSEO 3.3.2