PMA8000 to GN750 wiring question

[jtrollin]

I am building my wiring harnesses and looking at the wiring diagram I got from Stien, it shows the all the shield grounding on the other end of the wires from the PMA8000 with no shield grounding on the PMA8000 end. I am looking at the manuals and the PMA8000 manual states that:

". All shields should be grounded at audio panel only. Other end remains floating".

The GTN-750 states that:

"AT GTN 6XX/7XX, CONNECT SHIELD GROUNDS TO THE CONNECTOR BACKSHELL -- THE SHIELD TERMINATION LEADS MUST BE LESS THAN 3.0". CONNECT OTHER END OF THE SHIELD PER THE REMOTE EQUIPMENT INSTALLATION REQUIREMENTS. IF NO SHIELD TERMINATION REQUIREMENT EXISTS FOR THE REMOTE EQUIPMENT, TERMINATE SHIELDS AS SHORT AS POSSIBLE, NOT TO EXCEED 3.0". SEE SECTION 2.11.4."

The two guides seem to conflict with each other, anyone know what is right here?

thanks,

[rleffler]

Originally Posted by jtrollin

". All shields should be grounded at audio panel only. Other end remains floating".

Yes, do this on all the audio lines.

Originally Posted by jtrollin

The GTN-750 states that:

"AT GTN 6XX/7XX, CONNECT SHIELD GROUNDS TO THE CONNECTOR BACKSHELL -- THE SHIELD TERMINATION LEADS MUST BE LESS THAN 3.0". CONNECT OTHER END OF THE SHIELD PER THE REMOTE EQUIPMENT INSTALLATION REQUIREMENTS. IF NO SHIELD TERMINATION REQUIREMENT EXISTS FOR THE REMOTE EQUIPMENT, TERMINATE SHIELDS AS SHORT AS POSSIBLE, NOT TO EXCEED 3.0". SEE SECTION 2.11.4."

The two guides seem to conflict with each other, anyone know what is right here?

They are both right. For all the RS-232 and ARNIC lines that are shield, terminate only one end of the shield.

Any lines that go to the audio panel, ground the shield at the audio panel. Any other lines, it's your choice which end to ground the shield. I followed Garmin's advice on my 650 and grounded all lines to it, with the exception of the audio out.

Remember there is a difference between grounding the shield and a ground wire.

bob