Pyramiding Wire Replacement

TM 11-7010-201-40-1/ET821-AA-MMI-010/E154 MTS/T O 31S5-2TSQ73-2-1

(8) Heat end of wire with soldering iron, and apply solder to wire; solder should flow smoothly under tab.

(9) When solder has cooled, clip off excess bare wire.

(10) Repeat steps (7) thru (9) for other end of wire.

(11) Bend wire back along body of jumper clip.

(12) Slide heat-shrinkable insulation sleeving over jumper clip and heat sleeving lightly by bringing soldering iron

close to sleeving until shrinkage stops.

(13) Install replacement wire by pushing each jumper clip down on wire-wrap posts.

(14) Carefully clean reworked area and reassemble MTS.

d. Pyramiding Wire Replacement . When new wiring must be installed, the degree of pyramiding must fit be

determined before proceeding. The general restrictions are:

(1) A wire that has been unwrapped cannot be rewrapped. If an adequate service loop is available, the wire can be

clipped and rewrapped; if not, a new wire must be installed.

(2) No more than three wires can be wrapped on a single pin; a wire that has been clipped off and left in place

counts as one of the three.

(3) Unwrapping a clipped wire and sliding the topmost wire(s)-down is not permissible.

An example is provided where a wire must be replaced as shown in figure 3-14, example A. Wires A and B must be

removed to remove wire C from pin 1. Figure 3-14, example B, shows the wires removed; and figure 3-14, example C,

shows the new wires (AA and AC) installed, with the exception of wire AB to pin 4. Since three connections are already

in place (X, Y, and B cut-end), these three connections must be removed to permit wrapping wire AB. However, if wires

X and Y were to be replaced, a pyramiding condition could been countered where it may become impractical and too

time-consuming to replace all other affected wires; i.e., all other wires related to wires X and Y replacement. A judgment

is then necessary before starting to replace any wire, whether card cage repair or replacement should be undertaken.

e. Wire-Wrap Repair. Use the following procedure for permanent repair of broken wire-wrapped wire.

(1) Carefully strip insulation from each end of wire to length shown below.

(a) Strip 26 AWG wire 718 inch.

(b) Strip 30 AWG wire 1 inch.

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