hooking up 508d to viper 5904?

I don't think they are the same.

This is quoted from the install manual:

< size=3 face=Futura>< size=3 face=Futura>

Note: < lang=KO size=2 face=Futura-Book>< lang=KO size=2 face=Futura-Book>Sensor ports 1 and 2 cannot support sensor 508D due to current limitations. These ports are also

constant power and ground connections.

End quote.

Don't know what the problem is yet... but I know what it's not.

It says exactly the same on the 5704. How do you think we wired up the 508d before mux ports? The only difference is that the ground on the mux is GWA rather than constant.

So it's a misprint or just poor documentation on DEI's part? Not having installed it as yet, I've taken my 5904 apart and traced the circuit topology. What I have found is that there's a 100 ohm resistor between the decoupled/regulated 12V rail and the 12V output to the sensor. Upon power up, I found the sensors cause a 1.00 - 1.3V drop across the final 100 ohm resistor, with the final voltage reaching the sensor being VCC - 1.5V which suggests to me that there's a current draw of around 10 - 13mA. The difference is, the shock sensor doesn't draw the full amount until triggered whereas the 508D draws this full power constantly. As such, this leads me to the following conclusions: 1) It's perfectly OK to plug the 508D into the sensor port given the little current drawn (13mA maximum). 2) Despite point 1, it would still be good RF practice to only power the 508D when the vehicle is armed. No point in generating any RF where it's not required. While the microwave radiated isn't enough to even take down a Boeing's avionics, it's still good practice nevertheless. That's why I'll be disconnecting the ground wire from the 5904 end of this sensor lead and connecting it to the GWA wire of the 5904 system instead. Otherwise, if you're happy to keep the RF going all the time, then just plug it straight in and you'll be OK.

Artstar, you are absolutely correct and I agree with every point you made. 1) I suggested to someone else he plug it in on a 5704 worked perfectly. 2) I'm pretty sure that on previous models the mux port ground pin was actually GWA and that could be the problem. When they misprint, DEI usually get their lock unlock and aux wires the wrong way round so I don't think it's a misprint they should have suggested people do exactly what you did.

I plan to get a little cheekier with mine on second thought and will cut the ground connection to the actual sensor connectors on the 5904 and reterminate them to the GWA internally. That'll make for a neater solution. I wonder why DEI changed that anyway?

Because a Chinese circuit designer had a brain fart!

Yep, I'll accept that answer. :)

Can you just hook up the ground wire from the sensor to the gwa H1/6 of the 5804?Don't know what the problem is yet... but I know what it's not.

*5904Don't know what the problem is yet... but I know what it's not.

Yes.