z130BT accessory wire behavior and amp turnoff "pop"

[JohnK]

When I wired my Alpine amp remote turnon wire to the z130BT's accessory wire,  turnon was fine,  but when I turn off the radio the 12v on the accessory wire stays on for a couple of seconds after the radio is off, resulting in a "pop" in the amp once the accessory wire voltage drops.

 

Is this the behavior of the AVIC head unit accessory wires?   Since the head unit appears to be powered by the 12v switched, when I turn off the car it essentially kills the power to the radio.  Even though the radio has a 12v constant lead, it doesn't seem like the radio elegantly turns off accessories before shutting itself down.  For a high end head unit like this, I would think it would handle this properly.

 

If the AVIC head unit is supposed to kill the accessory wire voltage immediately, then is it possible that the car's antenna amplifier is hanging onto some voltage for a couple of seconds. which is keeping the amp on?

 

For now I have wired the amp turnon directly to the car's ignition turnon, which eliminated the turnoff pop but now has a slight (much lower volume) turnON pop because the amp is powering up before the head unit.  I think I can add a delay to the turnon wire ... but ultimately I would like to use the "proper" method of coordinating on/off between the head unit and the amp.

 

Are these AVIC head units supposed to elegantly power down the amp before turning themselves off when the 12v switched from the car is turned off?

 

Thanks.  John

[JohnK]

Fyi, I sent an email to Pioneer tech support and received a response today:

 

=====

 

Thank you for contacting Pioneer Electronics (USA) Inc.

1 The red wire is not the main power, it is used to power the unit off and on. The yellow wire is the main source of power.

2. It is normal for the blue/white wire to remain active until the vehicle is turned off. It should kill the voltage as soon as the radio is turned off.

Sincerely,

Rocky
Customer Service Representative

 

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So I would guess that the car's antenna amplifier, which is also connected to the accessory wire, has a capacitor in it which drains excess current after the radio cuts off, thereby leaving voltage in the accessory wire for a couple of seconds more.  The next time I pull the radio (seems like it's a becoming a monthly ritual now) I will test and swap wires, connecting antenna amp to switched 12v, and leaving the speaker amp as the sole device connected to the accessory wire.  We'll see if this clears it up.

[JohnK]

Okay, I pulled the head unit today to check the voltage on that blue/white remote turnon wire.  First I disconnected the car's antenna amp to make sure it wasn't supplying residual voltage.

 

When I turn off the car's ignition, the remote turn-on wire remains at 12v for about two seconds.   It does not kill the voltage immediately, as the Pioneer Tech Support rep suggested should be the behavior.

 

I don't know if any of the other wires to the head unit are causing it to supply residual voltage.  I don't imagine this is configurable in the head unit.

 

If this is how the head unit is designed, this is a serious design flaw.  

 

For now I have to rewire the amp back to the car's switched 12v, and I'll add a delay box to eliminate the small pop during turnon.

[Cwolfey]

If you wired a relay to trigger the amp turn on with remote lead & ignition, this would keep the same turn on delay as before and drop out immediately when key is turned off.

 

Like this:

 

85 - ground

86 - Pioneer remote

30 - Amp turn on

87 - Ignition

[JohnK]

That idea makes sense ... however isn't the delay box supposed to have it's positive lead attached to solid 12v and not switched?

 

My PAC TR-4 should be arriving today so I can try the install this weekend.  I don't really want to pull the radio yet again, so I'm going to install it at the amp in the trunk and see how it does there. 

 

But if that doesn't solve the pop compeltely, I'll try your suggestion next.

 

Thanks.  John

[JohnK]

Installed the PAC TR-4 in the trunk ... didn't work -- one second delay is not enough.

 

I know now that the PAC TR-7 is configurable for much longer delays, but now that I have the TR-4 in hand I figure I should try the approach suggested by CWolfey, which will definitely resolve the turnon pop.  And as long as the turnoff is immediate this will resolve my overall problem.

[JohnK]

Okay I tried Cwolfey's suggestion of powering the PAC TR-4 via the switched 12v wire instead of constant 12v, and it works like a charm   

 

So to clarify the wiring assignments:

 

TR-4   -->    car/harness

 

Constant 12v --> switched 12v

Ground --> ground

Signal In --> radio antenna/accessory wire

Signal out --> amp remote turn-on wire

 

Thanks.  John