Relay and Clarion DXZ615 woes!

So far so good with my ongoing installation. I've had little problems that I've managed to find and eliminate, now after final amp-rack wiring I have this new one. Argh.

I'm using a Bosch 30A relay attached to my Clarion's Remote-ON which then triggers both my amps and two fans. The problem right now is that when I remove the key from the ignition (which should shut everything down), my power antenna starts having a fit.

I have yet to take my multimeter out to the car (it's bloody freezing and I don't have anyone else around right now to power down the system while I use the meter). The antenna just makes nasty ratcheting noises - it doesn't extend when powering down. I suspect it's getting a bit of voltage but not enough to cause it to go up.

The antenna works fine when the system is powered. It goes up and down as I switch in and out of tuner mode on the head unit.

When using a relay in a circuit that isn't designed for one, apparently you should place a diode in parallel with the coil. I have such a diode and it's in parallel with the coil - the correct end of the diode is also connected to the proper terminal (the one receiving the remote +12v). When not using a diode, apparently you can have negative voltage go back through your remote line as the coil loses its charge - which is bad for all sorts of transistors, etc..

Anyway, I suspect that I'm having a problem with this voltage and it's somehow going through the head unit and back out the antenna line. The antenna makes noise for a little longer than I'd expect however.

If I unplug the remote connection before shutting down the car, the problem doesn't occur. If I don't use the relay, but connect the Clarion's remote directly to the amps, the problem also does not occur. I think I'm looking in the right place. :)

One thing that might get rid of this problem is using the empeg's Remote line to trigger the relay, but I don't relish digging into my dash again. Plus if there is a negative voltage spike, I certainly don't want it in the system. :)

Anyone have any experience with relays in this type of install? Any suggestions welcome - even if suggestions for additional specific troubleshooting steps.

Bruno

It's possible the antenna has a high impedance input on its switch line, and there's enough capacitance the other side of the relay contacts to cause the voltage to drop very slowly.

I suggest trying something like a 1k resistor to ground from the antenna control wire.

Hugo

If you are in/around Toronto (guessing), then the nice little electronics shop on Queen St West, just east of Active Surplus, has nifty little hybrid packages they call "solid state relays", from 3 to 40 amps capacity. These have built-in opto-isolators, trigger on <1ma or <7.5ma (depends on model) over a wide range of DC voltages, and work nicely for this kind of stuff. Some are for AC loads, some are for DC. Prices from $5.40 to $24.50.

Cheers

Close enough that I may be able to pass by there this weekend sometime. Thanks for the tip.

Bruno

Now, by putting the resistor to ground, do you mean simply splicing off from the antenna control lead to the resistor to ground? So the control lead would look somewhat like a "Y" or "T"?

It was also suggested that even though the diode on across the coil should disipate the coil's charge, that I might try putting a diode inline with the remote wire, to prevent any reverse current.

I'll meter the various points near the relay tonight if I have the chance, to find out exactly what's happening.

Thanks.

Bruno

Yes, a T joint (ie, you don't interrupt the signal, just put in a path to ground to make sure the voltage on the other side of the relay falls quickly when disconnected from power).

I'd try this before buying new relays, etc. It may well be this simple.

Hugo