AT&T Bell System Plant Series Adjustment Procedure page 13

_:,__ REVERSE (REAR)
I
LOOP SENSE
VACUUM
CHAMBER
-
SUPPLY
()
TAKE-UP
VACUUM
CHAMBER
Fig. 9-Vacuum Chambers-Shown with Chamber
Area Overlay Plate Removed
ISS 1, SECTION 034-368-701
(2) Install a reel of magnetic tape and stop the
tape with the BOT marker positioned airay
from the photosense head ( Fig. :3).
(3) Adjust potentiometer
1-{;3 (
Fig. G) on the
photosense and interlock printed cireuit board
PIB. Adjust R:3 until the \'Oltmeter indieates a
trans1t1on from a high state (
+
12 volts) to a
low state (0 volts).
(.J)
l\Iove the tape until the BOT marker is
beneath the photosense head. Counting the
number of turns, adjust R3 in a countercloekv\'ise
direction until the voltmeter indicates a transition
from a low state (0 volts) to a high state (
+
12
volts). The potentiometer adjustment should
require approximately three turns before the
transition occurs.
(5) Readjust R:-3 in a clockwise direction halfwa.,·
back to the transition point of (:3).
(6) Connect the voltmeter to TPl-21 using TP2-:35
as the 0-volt reference. Repeat the proeedure
in (2), (:3), (4), and {:)), adjusting potentiometer
R21 on printed circuit board PIB and plaeing
the EOT marker under the photosense head
during
(--1).
Page 13
13 Pages