Think I posted this in the wrong forum so posting it again here..

Hopefully someone can give me some ideas on this issue... A little background on myself, I'm an electrical engineer and have installed many car stereos over the years.. I have a 2017 SGS, bought it with the rockford T400x4ad and speakers installed already. Lately, the battery has been going dead when the bike sits even with the tender on. Finally i had enough and started troubleshooting. First i removed the fairing and monitored the states of the amplifier relative to IGN position. In ACC or IGN mode the amp turns on, when the switch is off amp goes off, at least initially. Sometime after the bike is sitting the amplifier turns on and stays on which is draining my battery. Even with the remote wire completely unhooked, the amp is staying on and i was reading battery voltage at the remote pin at the amp. This is a strange one and is driving me crazy. When the amp decides to stay on, it's drawing around 900mA, which obviously will kill the battery pretty quick. Amp seems to work fine otherwise, tunes sound good and all that. What's strange to me is that the amp turns on by itself after the bike is sitting. Why in the world would this be happening unless the amp itself has an internal short or there is some inductive path somewhere else causing it to activate. Before I go and swap another amp, just wondering if anyone else has experienced this issue or would have any clue what could be causing this. Any help appreciated, thanks in advance.

-Mitch

 

What amp and how is set to sense it needs to be turned on? Maybe it's set to sense signal on the audio input and that's triggering it? If it's set for remote on using power on the lead and it's turning on with that lead disconnected (and you're picking up power on the input pin) it sounds like the amp is faulty.

 

Sounds to me like you have a bad optoisolator that controls the power MOSFETs. The opto gets the control voltage and then triggers on the MOSFETs. When they go bad, things like you describe occurs. And yes, I am/was a electronic tech in a prior life. Might be a good time to upgrade your amp unless you have the ability to repair it.

 

For us retards. Via Google

An opto-isolator is an electronic component that transfers electrical signals between two isolated circuits by using light. Opto-isolators prevent high voltages from affecting the system receiving the signa

 

Ugh, that's what i was hoping it wasn't. Any suggestions on a good substitute that would fit the same form factor as the rockford? I'm pretty decent with a soldering iron, i'm no stranger to circuit boards so repairing it could be an option. With the current state of supply chain however don't know if i could even get parts. What's weird is that after riding all day over the weekend, it seemed to work as it should. Never had an amp do this after it sits for some time. Thanks for the input.

 

I have it connected to the plug on the upper left side of the fairing if you're facing the front of the bike, if you're sitting on the bike would be right side. It seems to work properly initially, cycling through key states it shuts off as it should. That would be great if it's just that easy to move the connector. I'll have to see if I can dig up any wiring diagrams to see what's what. Thanks for the input.

 

It's the rockford fosgate T400XAD 4-ch amp. Pretty simple amp, not many configurable switches on it. Just has speaker inputs/outputs, batt, GND and remote in.

 

You've got this wired using speaker (high-level) outputs from the HU? If so I'm thinking that the amp is somehow sensing signal on the amp inputs and powering up. I can't see a way to disable and force the amp to ignore input signal sensing. This from the manual:

High Level Input
Connect from source signal by plugging into the RCA input jacks at the amplifier. The input sensitivity ranges from 150mV-12V to accommodate signal from high-level (speaker) input. When utilizing high-level for input signal the auto turn-on feature is active. With the auto turn-on active, the REM becomes an output to turn on/off up to two additional amplifiers or other accessories

Maybe try using an LoC and converting to low-level amp inputs? Then the remote will act as an input and not an output. Just a thought but worth checking out IMO

 

Good looking out on that, I missed that note in the manual. I just went out and looked, i guess they are high level inputs, hard to tell. There's a jumper harness that plugs into the stock HU connector and then into the amp. Only 2 ch coming in but 4 coming out. I wonder if there's a way to adjust the input sensitivity, maybe it's set too low and causing it to trigger somehow.

 

It’s not a configurable option. Without access to schematics it’s not worth the effort to fix on the bench IMO. Normally I’m not a fan of adding components such as an LoC if they aren’t needed but in this case it would appear that it would be. Cheap and easy fix if that’s the case.