Lesson 2/Learning Event 2
c. Differences in Types of Main Frames. Improvements have been made in
main-frame design to incorporate self-restoring protectors and wire-wrap
terminals.
(1)
Self-restoring protectors.
New types of protectors automatically
restore
themselves to normal when the cause for their operation has been
removed
from the line.
This design quickly restores the line to traffic
without
the attention of a testman.
(2) Wire-wrap terminals.
New wiring methods include wrapping wire
around terminals rather than soldering. Since the wrapping is performed by
machine, all wire-wrapped connections exhibit uniform characteristics.
Further, the operation saves time, and ends circuit failures caused by
solder beads and clipped wire ends.
The terminals differ in basic design
from soldering terminals, being small, square, metallic projections from the
terminal boards. A tool similar to a small electric drill does the wrapping
quickly and accurately.
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