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  #11  
Old 04-13-2021, 06:33 AM
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Walt Walt is offline
 
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Location: Dallas/Ft Worth, TX
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Quote:
Originally Posted by mfleming View Post
instead of starting a new thread.

Garmin says there can be no more than 10mA per pin on the GAD 27.
Garmin also doesn't publish the milliamp ratting for all of their displays. I did find the GDU-4XX are 1mA per unit for the lighting bus but could not find the milliamp rating for anything else.

Seeing that I have 7 units with lighting buses and want all of them on one dimmer...I don't want to exceed the max 10mA draw on one pin and screw up the GAD 27.

Any insights??
I can't imagine what those 7 units are?
I run 2 screens on one output, a GTN on another, CP lights on another.

Things like audio panel, GMA, GTR units really don't need dimmers, their internal ones work just fine.

I don't think you could ever get everything balanced perfectly using just one dimmer pot.
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Last edited by Walt : 04-13-2021 at 06:35 AM.
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  #12  
Old 04-13-2021, 07:59 AM
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g3xpert g3xpert is offline
 
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Location: Olathe, KS
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Default Lighting Bus Input

Quote:
Originally Posted by mfleming View Post
instead of starting a new thread.

Garmin says there can be no more than 10mA per pin on the GAD 27.
Garmin also doesn't publish the milliamp ratting for all of their displays. I did find the GDU-4XX are 1mA per unit for the lighting bus but could not find the milliamp rating for anything else.

Seeing that I have 7 units with lighting buses and want all of them on one dimmer...I don't want to exceed the max 10mA draw on one pin and screw up the GAD 27.

Any insights??
The lighting bus inputs are typically very high impedance, most installations don't come anywhere near the 10mA limit. If you are putting 7 LRU's on one pin, we can double check just to be safe. Let us know what units you want to connect and we can calculate the max current draw the lighting bus inputs are capable of, collectively.

Thanks,

Justin
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  #13  
Old 04-13-2021, 09:02 AM
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mfleming mfleming is offline
 
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Location: Joseph, Oregon
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Quote:
Originally Posted by Walt View Post
I can't imagine what those 7 units are?
I run 2 screens on one output, a GTN on another, CP lights on another.

Things like audio panel, GMA, GTR units really don't need dimmers, their internal ones work just fine.

I don't think you could ever get everything balanced perfectly using just one dimmer pot.
The 7 displays are:

GDU460 PFD
GDU470 MFD-1
GDU470 MFD-2
GNX375
GTR200B
GMC507
GI260

So the interconnect drawing I have from SteinAir shows all those units connected to dimmers through the GAD 27.

I never considered just having the GDUs on the dimmer and the rest operated on the photocell. You're saying that setup works OK.

If everything not on a dimmer could be adjusted with the setup mode to be not too bright at night... that could work...


Quote:
Originally Posted by g3xpert View Post
The lighting bus inputs are typically very high impedance, most installations don't come anywhere near the 10mA limit. If you are putting 7 LRU's on one pin, we can double check just to be safe. Let us know what units you want to connect and we can calculate the max current draw the lighting bus inputs are capable of, collectively.

Thanks,

Justin
Walt recommended having just the GDUs on dimmers.

But, it would seem that if the manual gives us a limit on the milliamps through a single pin, the information should be available somewhere in the install manuals. The only reference I could find was the GDUs page 26-26 highlighted in green. The other displays did not have this info that I could find.

By the way, what does that sentence highlighted in blue mean?? It seems to suggest that more than on display per pin needs some sort of regulator.
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  #14  
Old 04-13-2021, 09:56 AM
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g3xpert g3xpert is offline
 
Join Date: Sep 2010
Location: Olathe, KS
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Default

Quote:
Originally Posted by mfleming View Post
The 7 displays are:

GDU460 PFD
GDU470 MFD-1
GDU470 MFD-2
GNX375
GTR200B
GMC507
GI260

So the interconnect drawing I have from SteinAir shows all those units connected to dimmers through the GAD 27.

I never considered just having the GDUs on the dimmer and the rest operated on the photocell. You're saying that setup works OK.

If everything not on a dimmer could be adjusted with the setup mode to be not too bright at night... that could work...



Walt recommended having just the GDUs on dimmers.

But, it would seem that if the manual gives us a limit on the milliamps through a single pin, the information should be available somewhere in the install manuals. The only reference I could find was the GDUs page 26-26 highlighted in green. The other displays did not have this info that I could find.

By the way, what does that sentence highlighted in blue mean?? It seems to suggest that more than on display per pin needs some sort of regulator.
In your installation, the regulated backlight voltage reference is the GAD 27. You can use a simple rheostat to provide a reference voltage to a GDU, but you would not want to use the same to provide a reference voltage to several different units, you want to use a GAD 27 or something similar.

Thanks,

Justin
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Please email us for support instead of using Private Messaging due to the limitations of the latter.
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