North N-541 User manual

SERI
ES
N-541, N-542
N-546, N-547
N-551, N-552
N-556 & N-557
Telephone Sets
NORTH
TELEPHONE HANDBOOK
NORTH ELECTRIC COMPANY
553 SOUTH MARKET STRUT • GALION,
OHIO

Administrative Offices & Plant # 1
NORTH ELECTRIC COMPANY
553 South Market Street
Galion, Ohio
REGIONAL WAREHOUSES
North Electric Company,
387  Market Street,
Galion, Ohio
Telephone 2-4201
North Electric Company,
754-756 Ponce de Leon Place N.E.,
Atlanta, Georgia.
Telephones EL 6564 and
EM 2618
NORTH TELEPHONE HANDBOOK
Issue No. II
Copyright

1956
North Electric Company
Galion, Ohio U„S,,A.

TELEPHONE HANDBOOK
CONTENTS

Paragraph

Page
List of Illustrations

ii
CHAPTER 1  INTRODUCTION
Section I Description 
1

1
II Service Applications

2  1
III Optional Features 
3 
1
IV Components  4-17 
1-3
CHAPTER 2

INSTALLATION
Section I General

18-19

4
II Connections

20-27
 4-6
III Adjustment

28-30

6-9
IV Test 
31 
9
V Final Procedure

32-33

9
CHAPTER 3

MAINTENANCE
Section I Inspection

34

10
II Trouble Shooting

35-39

10-18
CHAPTER 4  ADJUSTMENT
Section I General 
40  19
II Ringers
 41-43

19-21
III Dial
 44-50  21-23
CHAPTER 5  SUPPLEMENTARY DATA
Section I Replaceable Parts List 
25-26
II Table of Color Code: Colored Telephones
 26
III Table of Ringers and Ringer-Capacitors

26-27

Page ii
TELEPHONE HANDBOOK
LIST OF ILLUSTRATIONS
Page
Fig. 1 Telephone with Housing Removed
Fig. 2 Connector Block, Terminals 5
Fig.
3 Network, Terminals
5
Fig. 4
Wiring Diagram and Table of Ringer Connections
7
Fig, 5
Superimposed Ringing, Wiring Diagram
8
Fig.
6 Cradle—switch Latch, Wiring Diagram
8
Fig.
7 Dial and Cover, Rear View
13
Fig.
8 Handset, Exploded View
15
Fig °
9 Ringer Marking 15
Fig. 10 Straight—Line Ringer
16
Fig. 11 Frequency Selective Ringer 17
Fig. 12 Cradle—Switch
18
Fig.
13
Bias Check, Schematic Diagram 20
Fig. 14
Gong Adjustment, Schematic Diagram
20
Fig, 15
Telephone, Exploded View 24

Fig. 1. N-541 Telephone, Housing Removed

TELEPHONE HANDBOOK
CHAPTER 1
INTRODUCTION
Section I DESCR1PTION
I. GENERAL
The North N-541 type telephone is a modern high gain
anti-sidetone desk set. The controlled level provides
improved quality transmission on either short or long
lines.
Section II SERVICE APPLICATIONS
2. PURPOSE AND USE
The N-541 type set is designed for all classes of
common battery manual and dial services. It is
available for any of the following ringing methods:
a.
Straight line ringing and superimposed systems.
b.
Frequency selective ringing, harmonic, synchromonic and
decimonic systems.
Section II1 OPTIONAL FEATURES
3. NOMENCLATURE
The optional features available with the North N-541 type
telephones are identified as follows:
a.
N-541 Straight hand-set cord.
b.
N-542 Cradle-switch latch and straight hand-set cord.
c.
N-546 Coiled handset cord.
d.
N-547 Cradle-switch latch and coiled hand-set cord.
e.
N-551 Superimposed ringing, straight handset cord.
f.
N-552 Cradle-switch latch, superimposed ringing
and straight handset cord.
E,
N-556 Superimposed ringing, coiled handset cord.
h. N-557 Cradle-switch latch,
'
superimposed ringing,
coiled handset cord.
Section IV COMPONENTS
4. GENERAL
There are three major assemblies: the Handset, Base, and
Housing. The components of each are identified in the following
paragraphs.
5. HANDSET
Consists of the Handle, Handset Cord, Transmitter Cup,
Transmitter, Receiver, Transmitter and Receiver Caps.
Page 1

Page 2
6. BASE ASSEMBLY
Consists of the Plate, Cradle-Switch, Desk Cord, Network,
Ringer, Dial or Dial Blank, and for superimposed ringing systems
a cold cathode tube.
7, PLATE
The formed metal plate has a heavy corrosion resistant finish.
Four large rubber feet are riveted to the base,
8. CRADLE-SWITCH
a. Consists of
a frame,
switch spring pile-up and binder,
laminated phenolic actuating card, metal actuator brazed to the
cradle switch lever, and lever coil spring.
b. Model numbers ending in 2 or 7 have a latch on
the cradle switch. This holds transmitter circuit
open until release. button is pressed. See Fig. 6.
9. DESK CORD
A three-conductor cord with green, yellow, and red coding,
spade terminals and strain-relief provisions at both ends,
10. NETWORK
The telephone set contains a network Part No.
500,084, which includes the induction coil, talking
capacitor, a 45 mf ringing capacitor, equalizing
varistors, sidetone balance impedance, and a radio
interference suppression circuit across the dial
contacts.
11. RINGERS
a.
There are two types of ringers, Straight Line and Frequency
Selective. They are single coil types. The impedance is 600,000
ohms at 1000 cps. Coils have a d.c. resistance of 7500 ohms,
b. The straight line ringer (SL) is designed to operate over
the following frequency range.
Frequency 
Voltage Required
(cycles per second) 
(low bias)
16 cps

55 volts
20 cps

50 volts
25 cps  65 volts
30 cps

85 volts
33 cps  110 volts
12, STRAIGHT-LINE RINGERS
The armature for "SL" ringers has
a biasing spring swaged in
the end near the reed. In the rest position the bias spring
holds the armature toward the right hand pole piece and the clapper
near but not touching the high-pitch gong. This is to prevent the
ringer from tapping on dial pulses.

13.
FREQUENCY SELECTIVE RINGERS
On frequency selective ringers, each armature is mechanically
tuned to vibrate at a specific frequency and responds only to the
ringing frequency for which it is tuned. The rest position of the
armature and clapper is approximately equidistant between the pole
pieces and gongs.
14.
DIAL 7 TYPE
The pulsing and off–normal springs have double contact points.
With exception of the finger–wheel, all working parts are enclosed.
Contact springs, governor and gear train are enclosed in a dust–
tight plastic cover. The dial has a modern extended number plate,
standard number card, and is mounted on a snap-in bracket.
15. DIAL BLANK
The dial blank for manual systems has the same contour as the
type 7 dial and mounts on the snap–in bracket.
16, HOUSING
The housing is of high–impact plastic with threaded inserts
for mounting on the base. A hand–hole is provided for lifting
the instrument. The plastic hand–hole cover serves as a retainer
for the two plastic cradle–switch plungers.
17. CONNECTOR BLOCK
The molded connector block has 4 threaded inserts (2 double,
2 single) fitted with machine screws. The single inserts are
equipped with a
removable strap. The block has two, three, or
four terminals available. An additional insert receives the
cover retaining screw.
Page 3

Page 4
TELEPHONE HANDBOOK
CHAPTER 2
INSTALLATION
Section I GENERAL
18.
UNPACKING
Carefully inspect the local service order to insure installing
the correct instrument. Markings on the ringer coil may be
observed through the rectangular window in the base plate. The
coil is marked SL for straight line, SU for superimposed. The
frequency in cycles per second appears on frequency selective
ringers.
19.
LOCATION OF INSTRUMENT
The telephone set and connector block may be installed in any
practical location. Positions near grounded objects such as
radiators, sinks, gas or water pipes and electric outlets are
considered hazardous. This is especially true where grounded
station protectors are placed in the line. Keep the instrument
at least two feet from neon signs, fluorescent lights and other
apparatus known to create disturbances in telephones. Power
stations require special protective measures. Areas containing
explosive gases are particularly dangerous. Avoid areas of
excessive vibration. In all cases the location should have ample
accessibility for inspection and maintenance.
Section II CONNECTIONS
20. FACTORY CONNECTIONS
The ringer, dial and network are connected at the factory.
A wiring diagram, including figs. 4, 5, and 6, is packed with
each instrumento
21. DESK CORD
The three conductors of the desk cord are color coded and
connected to the network terminals (Fig. 3) as follows: GREEN
to Ll, RED to L2, and YELLOW to K. At the connector block GREEN
and RED are connected to the outside terminals, and YELLOW to
the center (strap) terminals (Fig. 2).
22.
LINE
a.
Connect the "LINE" (tip and ring) to the outside terminals
(GREEN and RED desk cord leads) of connector block. (Fig. 2).
b.
Divided Ringing — Connect a ground wire to the center

Fig, 2. Connector Block
Fig. 3. Network
terminal (yellow lead) of connector block,
c.
Bridged Ringing - At the connector block, connect the YELLOW
lead of desk cord to the same terminal as the GREEN lead.
d.
Superimposed Ringing - When shipped, phones are connected
for L2 - party. For Ll - party, reverse line at connector block.
For LI + or L2 + party the network connections must he changed in
accordance with Fig, 5.
Page 5