RJ21 Amphenol Pinout

The RJ21 connector is very similar to the 50-pin Centronics interface, but with screws to anchor it into place instead of bail locks. Sometimes called a "Champ" connector (referencing a series of connectors made by Amp), or an "Amphenol" connector (referencing the connector manufacturer), RJ21 interfaces are typically used for datacomm applications and support up to 25 Tip/Ring twisted pairs.

Cable pairs are identified by a two color sequence comprising of a primary color from one color group (white, red, black, yellow, violet) combined with a secondary color from a second color group (blue, orange, green, brown, slate). This gives 25 color combinations.

• White/Blue represents pair 1: eg, White with a Blue band is the tip on pin 26, Blue with a White band is the ring on pin 1.
• Violet/Slate represents pair 25: eg, Violet with a Slate band is the tip on pin 50, Slate with a Violet band is the ring on pin 25.

50 Pin / 25 Pair RJ21 (Amphenol)
telephony connector Colors

RING (B) Wire Color:		TIP (A) Wire Color:
Blue - White Orange - White Green - White Brown - White Slate - White		White - Blue White - Orange White - Green White - Brown White - Slate
Blue - Red Orange - Red Green - Red Brown - Red Slate - Red		Red - Blue Red - Orange Red - Green Red - Brown Red - Slate
Blue - Black Orange - Black Green - Black Brown - Black Slate - Black		Black - Blue Black - Orange Black - Green Black - Brown Black - Slate
Blue - Yellow Orange - Yellow Green - Yellow Brown - Yellow Slate - Yellow		Yellow - Blue Yellow - Orange Yellow - Green Yellow - Brown Yellow - Slate
Blue - Violet Orange - Violet Green - Violet Brown - Violet Slate - Violet		Violet - Blue Violet - Orange Violet - Green Violet - Brown Violet - Slate

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