MLX Wiring Revisited

[GroundWire]

Guys:

I've seen a couple of threads dealing with the wiring that the MLX phones need to operate. I'm posting this to clarify, and make sure I've got all my facts in order.
Using the pinout below for an RJ-45 connector, plugged into the station port:

1 2 3 4 5 6 7 8

W/G GRN W/O BLU W/B ORG W/BR BRN

Here's what I know, or rather, what I think I know.. (This is what you're clarifying for me.

4&5 [Pair 1], and 3&6 [Pair 2] are used by ALL phones..
and if I'm running a DSS on that station, I also want to connect 7&8 [Pair 4] as well, to get the -48v.

Is it really true that the third pair (1&2, GRN) are completely unused? Or does it do something really esoteric?

Thanks for the info!

- Joel

 

[Papagigo]

Joel,

Only the middle 4 conductors are used, unless DSS is added.

Mike

 

[ttech]

The 4th pair is alsi used if you use an mfm ans if you use OHVA.

-Don

 

[AndrePa]

I use 4&5 [Pair 1], and 3&6 [Pair 2] on all MLX phones, never had a problem. They have phantom power applied to [ pair 1 & 2 ] similar to 4 wire DCP ( defintity & Merlin II 74xx Phones ). Note DCP used [ Pair 2 & 3 ].

If the MLX phone has a MFM, or DSS attached, You need to put power on [Pair 4] 7&8 as well, 48 Volts. I also use [ Pair 4 ] on MLX 20L to be safe.

Pair 3 are unused on MLX phones

Hope this helps, Andre

 

[franke]

I would like to make one small observation that might save some grief down the road...

Your diagram shows the wiring for a 568-A cable, while the MLX ports and mounting cords are 568-B; therefore you should reverse your orange and green pairs (ie: Orange on pins 1 & 2, Green on 3 & 6).

franke