Mike Green9

2008 in winter storage, original battery.
Kenwood DNX8990HD head unit.
Arc Audio KS125.2 amp, powering Focal PS165 (4ohm) speakers in each door.
Rear speakers power by Kenwood internal amp.

Hi.

The above system has worked very well for 2 summers. This past August I began to notice that I had no door speakers. Recent diagnostics has revealed that the Arc Audio green LED is not on – hence no amplification. Note that the Arc Audio cooling fan is spinning, implying that the Kenwood is sending a proper trigger, and 12 volts is present at the Arc Audio terminals.

With Accessory mode ON, and the Kenwood powered up, voltage at the Arc Audio terminals is 12.08. With the battery disconnected, voltage across the battery terminals is 12.46.

When I use an external 12 volt 4 amp power supply (Kenwood and Arc Audio amp in place in the car), the system works perfectly – and the Arc Audio green LED is on solid. The no load output voltage of the power supply is 12.45.

I never suspected this was a low voltage issue, since all else works fine, and the DIC has always displayed 14.2 volts when the engine was running.

Question: I can understand why the Arc Audio is not happy with the voltage with the engine off, although that never was an issue before, but why did the Arc Audio amp complain about 14.2 volts this past Fall?

I don't want to start the vehicle until Spring. The battery is now being charged (C-TEK), and I will check again tomorrow.

Any thoughts?

Thanks,

M....

daverulz

My gut tells me it's an issue with your ground, but it could be a loose connection on either of the power terminals on the amp. Check that the connections for battery + and ground are both tight at the amp terminals, at the battery itself, and at your ground point. Also make sure that your ground point is clean making metal to metal contact.

Mike Green9

Hi.

Some further info - after C-TEKing the battery, I "jumped" the Arc Audio (trigger to 12 volt terminals) without Accessory or Kenwood powered up. The amp fired right up with a solid green LED. Seems like the Kenwood AND the Amp won't work at the same time.

I will check into the grounds this afternoon. Maybe run a dummy 8 gauge lead (booster cable) from the battery around to the amp and see if that works.

Thanks for the advice.

M...

Mike Green9

Hi again.

Some more playing - I cleaned the battery posts. I noticed the negative terminal was a dull grey - I made it shiny, along with the connector cable. Snugged them up real good.

I also checked the ground wire - I snugged up a connector. Looked fine otherwise.

I did some more voltage tests - I wanted to see if there was a voltage drop from the battery to the amp. I got 12.55 volts across the connected battery, and the same across the amp terminals.

Then I tried firing up the the Kenwood and the amp again. No difference, the amp still wouldn't fire up. (The fan whirs away - but no solid green LED.)

I tried another trick - with the Kenwood OFF, I jumped the amp (trigger and 12volts at the amp terminals), and the amp lit up just fine. THEN, I turned ON Accessory and the Kenwood. This worked perfectly - even at loud volumes. Seems like the turn on sequence makes a difference. The current situation wants the amp ON first, and then the Kenwood.

Maybe the amp is very sensitive to the lower voltage - and when the Kenwood is ON, the amp determines that there is insufficient voltage so it doesn't fire up. However, when the amp is already ON, a voltage drop caused by turning ON the Kenwood doesn't matter. I hope this isn't a sign that the amp is failing. I will try contacting Brad at Arc Audio and see what he says.

I may just have to shell out for a new battery after 8 years.

I will keep you posted.

Thanks for your help,

M...

Mike Green9

Hi.

Here is the response from Brad at Arc Audio:

"This doesn’t sound like an issue with the car. Something is wrong with the turn on circuit of the amplifier or the head unit. The amp should turn on with about 7-8 volts on the turn on lead."

M...

markcz

Sounds like the HU isn't putting out enough current on the trigger wire.

You can try installing an automotive relay on the trigger circuit. Under $10 at any auto parts store.

Connect the red HU trigger wire to 86, ground wire to 85, B+ to 30, and 87 to amp trigger terminal. If you get a relay with 87a don't connect anything there.

daverulz

Since the amp is turning on when you jump the battery and remote terminals, I would lean towards there being a problem with the remote output from the Kenwood. Now since this worked for a long time, I'd be hesitant to say "the Kenwood can't provide enough current" because obviously it could for 2 summers with no problems. It is possible that there is a fault in the remote line to the amp or that there's a problem with the remote output inside the Head Unit. I'd meter the remote line, make sure it doesn't have any faults to ground. I'd also meter to see how many volts I'm getting from the remote line, typically it's 12v. Finally, I'd meter to see what kind of current I'm pulling through the remote line. Remote circuits are usually only capable of providing a few hundred milli-amps so it shouldn't be an issue to wire your meter in line and see what the draw is.

markcz

But electronics do go bad, and since he's most likely out of warranty on the Kenwood, the relay would be a cheap way to get his tunes up again.

If the Kenwood trigger is completely gone, you could even use the trigger from the interface adapter that turns on the Kenwood to also turn on the amp. If you do that I would definitely use a relay.

daverulz

Yes, I agree 100% electronics do go bad!

If it's not physically a problem with the wire itself, and if the remote output on the Kenwood puts out enough current to throw a relay that would be a good solution. Otherwise, tapping into the red wire on the back of the head unit could turn the amp on. Most likely that approach would result in turn-on thump, hence the need for an amplifier turn on delay circuit that...you guessed it...uses a relay.

http://www.diymobileaudio.com/forum/...y-circuit.html

Mike Green9

Found the problem.

I tried turning on the system again and it failed. I jumped the trigger to the 12volt lead at the amp, and presto the amp turned on. The sequence of turning on the amp first, and then the Kenwood threw me off - I wasn't using the trigger in that scenario (trigger was jumped to 12 volts).

I checked trigger voltage to ground: 3.26 volts. Yikes!

I get the trigger from "P.Cont", Power Control blue/white wire from the back of the Kenwood. It plugs into the GM harness and I pick it up from the old Bose connector in the amp cavity. I know it used to be 12 volts, and it did work for a couple of years. Maybe something loose behind the HU??

I'm not really wanting to pull the HU at this time. I will investigate if there is another way to trigger the amp. Any ideas?

Arc Audio does have 'auto-sense' capability, but not on the model I have.

Thanks for your input - I never would have guessed that the trigger was bad. Apparently 3.26 volts is enough to get the fan whirring, so I assumed the trigger was aok.

What did we do before forums were invented?

Thanks,

M...

daverulz

I would pull the Head unit and check that the blue/white remote turn on wire is in fact putting out reduced voltage. If that is the case, see above. Good luck!

markcz

Depending how it's wired behind the radio, it could just be the interface adapter. Most HU remote triggers can handle any normal trigger load, but some adapters crap out after a while in C5/C6 (I believe because of the antenna circuit). You would have to pull the dash, but check the blue/white at the HU for 12v, if it's there then just install a jumper wire around the interface adapter.