# No output to L.F.ch., spk setup, sub strangely weak?



## Solidox2k (Jan 21, 2004)

hi. i dont really know much about car audio systems, never really had the choice for one w/my first old car (junked out ford grenada, so many memories *sigh*....), but since i got this sentra (hand-dwn, used. came w/a cd reciever, and sub), i'm starting to warm up to the idea  i've got a few questions, i'll try not to be too long-winded here....

here's the situation. when i got the car everything worked fine, got pretty good output from the sub, and the driver door was missing the speaker. it was a diy job and i had to work on the hookup, _properly_ connecting splices and wires, i also installed a speaker on the driver door.....but it didn't work.... so using the schematics in the haynes manual, it turns out that the left front speaker wires from the cdplayer were actually hooked up to 2 red wires...those red wires goto the illumination system... great, what was this guy thinking!? i didn't check, but im pretty sure those red wires were dropping voltage. not good. weeelll, now the cdplayer doesn't put out *any* juice to the left front speaker. i even tested the leads from the back of the cdplayer. nothing. where can i take the cdplayer to get it repaired? everything else seems to work but the LF speaker.

also, the plugs for the amp wires are on the back. it says mono output, and has two a/v plugs (i guess 2 plugs so you don't have to bother with adapters). there are 2 av wires from the amp (1 purple-left, 1 white-right) that connect to that, but for some reason only plugging in the purple one gives out bass to the sub, the white one does nothing, even though its securely plugged into the amp. when i noticed this, i also noticed the it wasn't giving out as much bass as it seemed to before. any thoughts?

the cdplayer has a/v plugs for front and rear speakers (in addition to the F/R spk wires coming out of the connector). the diagram in the manual show connections from those plugs going to an amp for each set (front and rear). do i _have_ to have an amp for 'em to get output? i tried testing it by running an a/v cable from the plugs to a plain speaker... all i got was static and interference, i unhooked it immediatly, worried that it would injure the speaker or the unit.

one laast question. the manual says specifically NOT to hook up speakers to it in a parallel fashion. why? can it screw up the cdplayer? i decided ok, then i'll hook up the front 2 speakers both to the right channel, so at least it seems balanced when sitting in the car. i ran into another problem. the speakers dont have pos(+) and neg(-) markings. is there any way test it, and if not, does it really matter when hooking 2 of them up in a series fashion?

hmm...so much for trying to keep it short :/ sorry for the eyesore, i hope some of you can help.


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## sr20dem0n (Mar 19, 2003)

hehe, damn a lot of questions

It kind of sounds like the LF channel on the internal amp is blown, as well as the left sub rca output, but I've never heard of an amp only blowing one channel while the others keep working fine. You could try an external amp if you have one already, but with that many strange problems I wouldn't be surprised if one or more of the rca outputs are fried as well. It's worth a shot though, as for the polarity of the speaker. Take a 9V battery and touch it to the terminals on the speaker, if the cone pops out then you have it right (the + on the batt is touching the + on the speaker and vice versa), if the cone moves in then you have it backwards. It really doesn't matter though, as long as both speakers match.

Definately don't wire your speakers in parallel to the cd player, that will show the internal amp a 2ohm load and it'll blow pretty fast. You can do it in series, but each speaker will only get 1/4 of the power that they (well, the R one) are getting now. If you do it just be careful you don't crank up the volume to compensate or you'll drive it into clipping. What brand is this cd player?


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## Solidox2k (Jan 21, 2004)

well, the cdplayer has 2 rca jacks comin' out from the internal amp, those plug into the external one i have. both jacks are puttin' out a signal, just somewhere between the ext.amp and the sub, the white cable isn't workin. probably just simple; about to get outside and do a little more with it.

9v batt... didn't even think about, i'll try that. the cdplayer is a Sony CDX-CA810X, one of those xplode series. unfortunately its one model before they started to include mp3 playback, oh well. the external amp is a Jensen XA2100 200w 2ch bridgable... looking for the docs on it, but the jensen site isn't up yet...


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## sr20dem0n (Mar 19, 2003)

how many total rcas plugs are there on the back of the headunit, 4 or 6?

So you have a pair of rcas running from the sub output on the headunit to the input on the amp. Then your amp is bridged to your sub? Plugging in only the white rca gives nothing, and plugging in either only the purple rca or both rcas gives some bass, but not too much. When you bridge an amp, it takes the 2 channels and adds them together and sends the total to the sub. If one channel isn't working then you'll only get half the power going to the sub (same as if you moved your balance all the way to the R or L). My guess is either one channel on your sub output from the headunit is blown or one channel on your input on the amp is blown, or your rca cable has a break in one of the wires. You said both channels are putting out a signal though (how did you measure this? voltmeter?), is this at the back of the headunit or at the end of the rcas by the amp?


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## Solidox2k (Jan 21, 2004)

wow, that was a quick response.

the headunit has 3 pairs of rca jacks on the back and one pair of rca cables coming out of it.
rca-pair1: audio front out
rca-pair2: audio rear out
rca-pair3: bus audio in
protruding rca cables (~3"): sub out (mono)

i can only hope its a cable break. i didnt test it with the multimeter i have, i just plugged the purple one by itself into each sub jack on the headunit. both gave signal, so.... i haven't tested the ext.amp jacks yet. umm...... it doesn't hurt the headunit/ext.amp when i test it for current/voltage drop, does it?


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## sr20dem0n (Mar 19, 2003)

oh alright
It won't hurt anything testing for voltage, when a multimeter is set on voltage it has a near-infinite resistance, so it's practically like just having the wires dangling there with only the air between them connecting them. It seems your sub outs are working normally (based on what you did, that's a good way to test). Next try the same thing at your amp, plug the purple plug into the L and R input on the amp and see if there's any difference. That should tell you immediately if the problem is your rcas or the amp itself. If it plays normally on both then it's the rca cable, if it stops on one plug then it's the amp. Hopefully it's the cable


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## Solidox2k (Jan 21, 2004)

hmm...well i tested the amp rca jacks. at first only one channel worked, i got bummed out and decided to re-strip the pwr wires that go in back, they were kinda frayed and i didn't want it inadvertently arching to the metal seat frame (its up front under pass. seat). weeelll, i got careless and didn't turn the key all the way off, so there was still pwr running through it; i put the pwr cable in and got pretty blue sparks for a split sec. great, so i turn it all the way off, pull the key out, hook it back up and pwr on, to see if any damage occured. seems its still fine. in fact, after that, now i get a signal on both channels. i lucked out. but when i tested the outputs on the amp w/the voltmeter i measured like 7 on the left ch. and almost 18 on the right (used to be almost zero on the L ch.). so for now i plugged the sub into the right ch.

how would i properly put the L and R outputs to one sub? normally i'd just take the L and R (+) feeds and put em to the (+) wire for the amp, and use one of the (-) feeds on the amp to complete the curcuit. is this safe?

one more thing. how do i properly clean a dirty speaker? can i just use a damp cloth?

heh. i had so many questions here, i really appreciate the help.


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## sr20dem0n (Mar 19, 2003)

how you hook it up will really depend on your sub and amp
as it is, I don't really know wtf is going on with that amp. It's possible your L channel has some bad connection on the way from the headunit to the amp. Either a broken wire, or a bad connection to the terminal on the amp itself. Misc testing with a voltmeter is really the only way to be sure where exactly it is


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## WhiteFox (Sep 4, 2002)

Could it be possible that you have the balance set to the right speakers only? I know that'd make me feel like a :dumbass:


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## Solidox2k (Jan 21, 2004)

WhiteFox said:


> Could it be possible that you have the balance set to the right speakers only? I know that'd make me feel like a :dumbass:


lol, nah, that was first thing i checked. i'll do some more testing when i can. as it is, im busy with interior work and might even have to re-wire the sound system (a short somewhere under the dash). thanx for the help though


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