values for rca testing needed
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=114188
Printed Date: July 13, 2025 at 12:36 AM
Topic: values for rca testing needed
Posted By: jhill20
Subject: values for rca testing needed
Date Posted: June 02, 2009 at 10:23 PM
So I've read and read, regarding testing what my rca's are outputting from the HU and either haven't read enough or it's not there...Anyways, I have an IVA-W200 going to a PPI PC2150 into a 10" bass tube for the time being, (glassing a box for my first string stuff), last night all of a sudden deck turned off completely then back on again...oddly i noticed that there was no bass being produced from the sub. Turned it on and off multiple times from the HU with no response. recently installed RCA's, no name brand, I checked wiring at rear of HU couldn't really pinpoint anything. I ohmed the RCA's, both the shield and inner line separately, and I have good continuity and they don't appear to be shorted internally either. So I assume they are ok?...
So what exactly am I looking for as far as values are concerned either at HU output or testing the RCA's themselves going into the amp?
Apologies for the long post, I am a auto tech and know how frustrating it is not to have a somewhat complete story...
------------- Josh
Replies:
Posted By: haemphyst
Date Posted: June 02, 2009 at 11:01 PM
It's likely you won't get a good number, unless you have a signal disc. 60Hz tone, and set your meter to volts AC, with you deck at about 75% full volume - say around 23 to 25 (I have the same deck). You should read about 2V RMS.
How do you know it's the deck that's the culprit? What have you done to test the amp or the woofer? If you plug the RCAs into the hi-pass outputs on the back of the deck, do you get anything from the sub system? If not, I suspect the amplifier or the woofer, as if your speaker outs are still functioning, the pre-amp section is as well.
Have you turned the sub-out "off" if even accidentally? Did you check that?
------------- 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: jhill20
Date Posted: June 02, 2009 at 11:12 PM
I've turned the sub on and off via the HU and watch the remote voltage turn on and off. I kind of figured the test cd theory. I'm actually really hoping it's not the head unit!! The amp is turning on and I didn't have any knowledge of what I should be seeing as far as a voltage value coming from the Head unit at the RCA's so I'm here. Just to be safe I'm testing shield to inner line AC voltage correct...on the RCA right...
I was going to plug into the hi pass outputs at work just didn't get a chance yet.
Is it possible for the shield to ground in the head unit go bad for just one output? or would all of the outputs share the same ground internally...?
------------- Josh
Posted By: jhill20
Date Posted: June 04, 2009 at 5:19 PM
So just in case someone else read this. I figured out my problem. It was the subwoofer. It's blown. I'm assuming that the amp was set to the incorrect resistance setting. which is easy cause the button to select which mode you want just has the two modes listed to the side of it. It doesn't specify that one is down and the other up...pretty good idea! thanks for the help. Much appreciated
------------- Josh
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