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Would a bad ground limit voltage?

Old 09-08-2004, 06:38 AM
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Hi gang, I recently purchased a used RF 800A2, did a temp install just to get the beats thumpin, all worked well for a week, then it started shutting off on me, now I can't get it to come on at all. I have my doubts that its an amp problem since the guy I bought it from has had it for 3 years and I've known him longer than that, plus it worked great for a week or two.

In trying to diagnose the problem, (on advice from the manual for the amp) I started measuring voltages, I've got a good 16 V when the truck is running from the bad and to the amp, but if I measure accross the +ve and -ve terminals of the amp it only gets about 10 V, which it says in the rockford manual should be 10.5-15.5, so I suspect it may be a bad ground, any thoughts?
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Old 09-08-2004, 07:01 AM
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dont measure across the terminals u will get a gay reading. measure the wires. yes bad ground would make your amp act like that.

[ September 08, 2004, 08:03 AM: Message edited by: Father Yuli ]
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Old 09-08-2004, 07:04 AM
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Yea, sounds like it could be... make sure the connection is solid with bare metal/metal contact... If that dosen't do it, go over all the wiring and make sure it's good...

I wish my car made 16v while running [img]graemlins/headbang.gif[/img]
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Old 09-08-2004, 07:12 AM
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Thanks guys, here's what I did, I measured across the terminals (should act same as the two wires at the terminals, just easier to get the probe on) and got 9-10V, then kept it to the +ve terminal and picked a different ground and got 16V.

It seems odd to me though that it would work good for a while, and then crap out :S you'd think if it was bad it would have been bad all along, no?

[ September 08, 2004, 08:13 AM: Message edited by: Vanilla_Gorilla ]
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Old 09-08-2004, 07:56 AM
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I had a ground that work gret for a month then got noise in the system ooked at the ground and there was white crap built up around it. Macke sure it is on bare metal and tight.
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Old 09-08-2004, 08:33 AM
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Then coat both side w/ grease or paint or liquid tape to keep moisture out.
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Old 09-08-2004, 02:16 PM
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I see people change batteries all the time when cables and terminals jsut need to be cleaned/tightend. They make cleaning and protecting sprays that work well.
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Old 09-08-2004, 05:07 PM
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if you have less than optimum voltage the chances are it could be your power or your ground
you need to eliminate one to say its one or the other
not to be i see to many posts that everybody jumps on and say oh its this or that
you must eliminate one before calling it

so to do this you need your amp on driving a volume to load the amp

now check the voltage at you battery terminals
now put your probes on the power terminal and and one on your amp terminals
is the voltage close to your batterys?

now find a piece of metal that you can clean off and optain a descent ground close to the amp
now put your probes on the power terminal and one on your other ground
whats your voltage there?
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Old 09-09-2004, 03:41 AM
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Here's the sequence I used to test it, truck running amp not not b/c it isn't working, hence this post :

1. Measured Voltage accross +ve and -ve terminals of amp, readings were 9-10V.
2. Measured Voltage at the battery, 16 V.
3. Measured Voltage after under hood fust, 16 V
4. Rechecked volatage across amp terminals, 9-10V
5. Checked voltage from postivie terminal of amp to alternat ground, 16V.

Hence my question about the bad ground causing my amp to keep quitting occasionally to the point it won't turn on now. What got me thinking to check was the rockford manual saying the amp won't turn on with less than 10.5 V.
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