Amplifier output

WILLIAM TESENE

MEMBER
1988 FORD BRONCO
5.8L
V8
4WD
AUTOMATIC
200,000 MILES

I have a fairly large amp sub setup in my truck. I have been installing stereo systems for 30+ years and have never run into this problem. I hav3 2-12" subs, each with its own amplifier. I'm running 1-0 gauge from the battery to a 4 fused junction block with 8ga to each amp from it. Also have 1-0 ground wire also to a junction block with 8ga to each amp approximately 15" long. I am using a 12ga remote turn on wire from the head unit. There is all of a sudden no output from either amp or sub. All voltage checks out at 13.8 each amp, no protection circuitry has been triggered, and I have tried at least 5 different sets of RCA's, and even went so far as to change head units trying to narrow this down. I am at a complete loss as to what is causing this. The subs also check out with my meter as good. The whole system worked fine, then inexplicably, didn't. Any help would be great. Also, what should I be getting for a reading on the amps TCA outputs when powered up? I don't have a clamp meter, just a multimeter. And what should I set it on to get a reading if a multimeter alone will even work?
Thanks in advance.

3 Replies

STEVE W.

MECHANIC
13,588 POSTS

If you are not getting sound out of them I would say the amps have failed internally, many have fuses on them and fuses on the boards inside as well. For testing you need to see if you have audio from the head unit to the amps inputs, for that a couple small speakers should work fine, just connect one to the heads output at the amps input and the other to the amps output. If you have sound at the inputs of each amp but nothing coming out, the next step would be to run a power bypass line from a battery to each amps power, that takes the vehicle power and wiring out, Connect the amps remote power to that as well so they are turned on, then test again. If you still get no sound out with the power bypassed and using test speakers and knowing there is an input signal then the only thing left would be if the amps are damaged internally. It would be the same as connecting them outside the vehicle for testing.
How are the amps turned on? Remote activation through the head unit or? Check that circuit as well.

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Saturday, November 21st, 2020 AT 12:08 AM

WILLIAM TESENE

MEMBER
8 POSTS

Hi Steve, and thanks for taking the time to respond. I have actually tried to test the components just as you mentioned, and still nothing. I'm afraid there may be internal malfunctions. The amps are both being turned on via the head units remote turn on wire, but that also has me confused seeing as its outputting 13+ volts. I was under the impression it shouldn't read more than 4v according to the specs. I don't know, the whole thing is rather disturbing because as I mentioned earlier, the amps haven't triggered any of the protection circuitry. The subs also still play when wired directly to a speaker level output of the head unit. The subs also make noise when powered up thru the amps, they have no turn on circuitry protection, so I know there is still some signal coming out of the amps. Still struggling with it.
Thanks for the suggestions.

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Saturday, November 21st, 2020 AT 1:38 PM

STEVE W.

MECHANIC
13,588 POSTS

That sounds like internal failure then. If you cab find the schematic of the amps it may point toward something like internal fusing, that or just open one up and trace the signal through the board. What brand and model are they? Maybe I can find something on them to help.

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Saturday, November 21st, 2020 AT 3:42 PM