Date: Sun, 16 Aug 92 08:13 EDT
From: rsiatl!turner@rsiatl.UUCP
Newsgroups: comp.dcom.telecom
Subject: 66-Block Wiring Help
Organization: TELECOM Digest
X-Submissions-To: telecom@eecs.nwu.edu
X-Administrivia-To: telecom-request@eecs.nwu.edu
X-Telecom-Digest: Volume 12, Issue 637, Message 2 of 7

Gabe Weiner writes:

> The clips in a given row are connected to each other.
 
On a standard white 66M1-50 block the left two clips are connected, as
are the right two. The left two clips are designed for wire to enter
above and to the left of the clip.  The wires for the right two clips
should enter from to top and exit to the right.
 
66 Blocks are also available in several other formats such as all four
clips connected, or pink "feature blocks" used in 1A2 key systems with
five rows of clips, four designed for wire to enter on the right and
one for wire to enter on the left.  All five clips are connected.  66
blocks can also be had with a RJ21X jack with the wires either
attached to the back of the block or punched down on one row of clips.
The RJ21X looks like an overgrown Centronics connector.
 
> Tip is wired over ring

Yes.

> A particular row is "free" if it is connected at one side only.  If
> there is only one wire in a row, there's nothing connected to that
> pair, at least at that block.
 
Unless the is a RJ21X jack and something is connected to it.
 
> Tracing a particular pair involves putting a tone genrator on one
> side, and then waving an inductive probe around on the other end until
> the matching pair is found.
 
This is one way of doing it.  Usually wires are tracked by the color
code and cable/block number
 
> Wires do not need to be stripped before being punched in, since
> the clips will break through the insulation as the wires are
> punched down.
 
Exactly.  Everything works really well as long as proper tools and
parts are used.
 
> Is there any significance to the colors in a 50-pair cable?  (i.e.
> are certain colors used for tip/ring or for certain line numbers? Or
> are they solely for the purpose of differentiating one from another 
> in the cable?)
 
Wires with a White, Red, Black, Yellow or Violet stripe on a Blue,
Orange, Green, Brown or Slate wire are ring.  The matching wire is
Tip.  To compute pair number add the values for the two colors from
the list below.  If there is a binder add the values for it's colors,
subtract one and multiply by 25, then add this to the sum of the
values for the pair colors.
 
Blue      1                    White    0
Orange    2                    Red      5
Green     3                    Black    10
Brown     4                    Yellow   15
Slate     5                    Violet   20
 
For example pair 16 would be Yellow Blue/Blue Yellow.  Orange White
binders contain pairs 26-50.
 
If for some reason you want to number wires rather than pairs for a 66
block or 50 conductor cable, Tips are numbered from 1-25 and Rings
from 26-50.  This is really only an issue when RJ21X jacks are used.
 
> Sometimes I see more than one wire punched into the same clip when
> there are vacant clips in the same row.  Is there any reason for doing
> this?
 
I can't think of any reason to punch down more than one wire per clip.
A wire can be punched down w/o cutting it by reversing the blade in
the punchdown tool.
 
> When running down a 66-block with one lead of a test set, what's
> the best thing to do with the other lead?  Just ground it somewhere?
> or connect it to the other side of one of the lines in the box?
 
This depends on what you are trying to do.  Grounding one clip will
allow you to find the tips and rings of live pairs.
 
> Any other tips in this sort of work would be appreciated.
 
Buy a good impact punchdown tool such as Dracon's.  Paladen has a new
punchdown tool out that may be cheaper and still give acceptable
results.
 

Pat Turner  KB4GRZ  turner@dixie.com