Need advice on system amp/power problem

[jdbnsn]

Hello CA-

I am having an issue I was hoping someone could help me identify. I drive a 2007 Scion Tc with stock alternator and "heavy duty" battery (about 2 years old batt). My system was installed by myself but I am a fairly novice electrician. It is comprised of:

-Kenwood DNN-990HD head unit

-4 gauge power lead

-4 stock cabin speakers

-Epicenter Audio Control

-1F Rockford Fosgate Capacitor

-Fosgate Punch 801s 800RMS

-Two 12" Fosgate subs (I forget which model#) bridged mode at 4ohms

This installation has been performing amazingly for years until about 6-8 months ago when the subs started cutting out when the volume was high or even moderate. The problem has persisted to this day and I have exchanged head units which produced no change, bypassed the Epicenter with no change. So I am now wondering what to check next? There have been no issues with the rest of the electrical system so I don't have high suspicion of the battery/alternator. Though I have not officially ruled it out. Could the amp itself be simply "worn out"? I didn't know they had a issue with this. There is no sign of overflow on the capacitor either.

Would greatly appreciate any advanced users who can point me in the next logical step to find the problem.

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[garychoffmann 10+ year member]

I would ditch the cap and check your power and ground for bad contact. Check your fuse to make sure it's not corroded and your battery may be on its way out. Those rockfords draw quite a bit of current. I would ohm out your subs and make sure they are still good.

 

[jdbnsn]

Wow, thanks for the speedy reply!!! The contacts makes sense, I'll try that next. Do you mean ditch the cap all together or for testing purposes? Lastly, I don't know what you mean by "ohm out the subs", do you mean check them with a voltmeter for impedance? Appreciate your help thus far!

-Jon

 

[mylows10 5,000+ posts]

Take the cap out. Get a big 3 kit instead. More effective check voltage and continuity with a dmm sounds like your voltage is dropping to low

 

[bbeljefe]

Clean your battery terminals and check all of your connections. More often than not, battery terminals get dirty and the connections on them get loose and by saying that nothing has changed with your electrical system I take that to mean you haven't cleaned the battery terminals. ;-)

As for the cap, you don't need to get rid of it on an 800 watt setup, although I would recommend doing a big 3 upgrade so that your alternator current can get to the amp like it needs to.

 

[jdbnsn]

That makes a lot of sense, and no I can't say that I have cleaned the terminals since the battery was purchased. This gives me some projects for the week, thanks so much fellas! I'll let you know how it turns out.

-Jon

 

[jdbnsn]

Just a quick update. I installed the big 3 cables today using 4AWG from +B to alternator with fuse (currently 100 amp but I plan to determine the appropriate fuse and replace it later), and -B to sanded frame, and frame to engine block. This was what I read online as being the correct setup. The battery terminals were indeed corroded so I sanded them clean. This did not fix the issue, so I replaced the battery with a 700cca battery which also did not fix the issue. So next on the list is to bypass the cap which I am less comfortable messing with so I'll do that when I have time to read up on safety. Do you guys think I should do away with it altogether if the problem resolves, or replace it with a newer/larger cap? I always assumed it was protecting the system but from what I have been hearing it may not be doing that much. If bypassing the cap does nothing I am down to the amp and subs. Not sure how to troubleshoot them individually so maybe will have to replace both. Anyway, I am grateful for the help thus far.

-Jon

 

[jdbnsn]

To follow up for anyone who has a similar situation, it was the cap! The more I read on the forums the more I see people mentioning the cap being the weak link. Seems to be correct, everything else checked out fine and when I finally got down to testing without the cap in place the problem vanished. Thanks for your help!

-Jon