Page 1
BELLSYSTEMPRACTICES SECTION 501- 165-117
AT&_ Standard Issue2, September 1982
72-TYPE STATION DIALS
IDENTIFICATION, CONNECTIONS, AND MAINTENANCE
1. GENERAL
1.01 This section contains information on the f
72C3A manufacture discontinued (MD),
72D3A (MD), and 72E3A (MD), 72H3A, 72J3A, and
72K3A dials (Fig. 1, 2, 3, and 4).
i.02 The reasons for reissuing this section are
listed below. Revision arrows are used to em-
phasize the more significant changes.
• Add information on 72H3A, 72J3A, and
72K3A dials
• Show 72C3A, 72D3A, and 72E3A dials MD.
1.03 The 72C3A (MD) dial replaces the 35A3A, t
35Y3A, and 35Y3D dials used in 2500- and "
2554-type telephone sets. The 72D3A (MD) dial re .... ,_
places the 35AH3D dial used in some DESIGN LINE*
decorator telephones. The 72E3A (MD) dial replaces
the 35BB3D dial used in TELSTAR* telephone (DE- Fig. 1--1_72C3A (MD) Dial, Front View4
SIGN LINE decorator telephone).
/
1.04 SThe 72H3A, 72J3A, and 72K3A dials replace
a 72-type dial, determine if a polar- (MD) dials, respectively. These dials are similar ex-
ity guard has been installed in con- cept for the mounting brackets, switch plate, and
Before replacing a 35-type dial with the 72C3A (MD), 72D3A (MD), and 72E3A
junction with the 35-type dial. printed circuit board materials used in
Where no polarity guard exists, re- manufactureAI
move the 3g-type dial and refer to
Table A for 72-type dial connections
and handset cord jack lead connec- A. Purpose
tions. If a polarity guard exists, it
must be removed and the telephone 2.01 The 72-type dial is an electronically switched
set wiring arranged to agree with 12-button TOUCH-TONEr telephone dial. Ten
the factory wiring before a polarity of the pushbuttons are used for number or number
guard was installed. Refer to appro- and letter calling and two pushbuttons designated *
priate telephone set connection sec- and # are for special services.
tion in Division 502 for 2500- and
2554-type telephone sets and Divi- B. Ordering Guide
sion 503 for DESIGN LINE decora-
tor telephone. 2.02 Order dial as follows:
•Registered Trademark of American Telephone and Telegraph
Company.
Not for use or disclosure outside the
Bell System except under written agreement
Printed in U.S.A. Page 1
2. IDENTIFICATION
_.Trademark of American Telephoneand Telegraph Company.
NOTICE
Page 2
SECTION501- 165-117
TERM NAL D .],:I
• -_ f ,/ .......'
TERMINAL
Fig. 4--$72H3A Dial, Rear View41
Fig. 2--072C3A (MD) Dial, Rear View(I • Dial, $72H3A0 (buttons and coverplate are
gray, button graphics are white)
• Dial, $72J3A¢ (buttons and coverplate are
.........
white, button graphics are black)
• Dial, $72K3AII (buttons and coverplate are
black, button graphics are white).
C. Design Features
2.03 Each of the pushbuttons, when operated, gen-
erates a dual tone multifrequency signal dis-
......................................................... frequencies for each button. Both the signaling and
tinctive to that button. Figure 5 indicates the
common switch functions are provided by the 677F
(Fig. 6) hybrid integrated circuit (HIC).
I_z A feature that is recognizable to the
short travel button which operates a
_ _ user of this dial is the "feel" of the
cIick disc switch similar to that used
Fig. 3--$72H3A Dial, Front View_l on many calculators.
2.04 The 72-type dial contains a polarity guard
eliminating the possibility of improper opera-
tion due to line reversals.
2.05 Each dial has eight spade-tipped leads (Fig. 6)
for connections to the telephone set network
and one screw terminal (D) located on the back side
Page 2
Page 3
1209 _.l 1336_ 1477% 4. MAINTENANCE
ISS 2, SECTION 501-165-117
697 _ sists only of determining if the dial is
There are no field adjustments for
defective.
Gl. M 0 4.01 TO determine if a dial is defective, proceed as
_ 77o_ follows.
(1) Verify wiring for secure and correct connec-
[ ells l_v]___ w:,v [_ s_20, tions.
(2) Check for presence of dial tone. If no dial tone
is heard, make test with 1013A or equivalent
l, t [o__ I t hand test set across incoming CO line to telephone
. -7_ -- 94t_ set. If dial tone is heard, make normal tests of tele-
sections.
phone set components as described in appropriate
(3) Break dial tone by dialing a digit as prescribed
by local instructions. If unable to break dial
Fig. 5--72-Type Dial Frequencies tone, replace the dial.
of the dial (Fig. 2) where a line switch lead termi- (4) Check all buttons for tone feedback to the re-
ceiver. If feedback tones are not present, re-
hates, place dial.
3. CONNECTIONS 4.02 To test dial frequency and amplitude outputs,
perform the following.
3.01 Connect the 72-type dial and make the neces- (1) Dial local number for testing TOUCH-TONE
sary telephone set wiring connections in ac- telephone dials, or dial local test desk and re-
cordance with Table A. quest access to the dial-test circuit.
(2) When second dial tone is heard, dial appropri-
Note: Refer to READ in paragraph 1.03 be- ate code for testing 12-button dials, dial digits
fore attempting to connect the 72-type dial. 1 through 9, and then *, 0, and #.
4.03 Replace dial if it fails to meet the tests.
Page 3
Page 4
SECTION 50 !- ! 65- ] | 7
ELECTRO-STATIC
SHIELD
BOARD 4 SC _ C4
SMTTCH 3 L2 18 Cll__]" -'_ _ ' C
ASSERBLY L1 17 / (O-BK)
1 L4 GN 20 (W) t'""
2 L3 S 19 R5 (14-BL)
5 C ,, C
i
H1
6 16 (BK)
7 H3 T 15 (R)
.__F _ [ c
14 .C3,_1 (BL)
8 .4 Tc13 j, _ C
9
R TG C2[_
10 NC PO 11 ! C7"'l(___.L
B 12 .. TJ (R-G) C
I\ " TO
: TEL
C8
I/ .
I\ C6"
SET
, _,. _ _ .,.. _ (G) (TIP
CR1 R2 R3
Fig. 6--072-Type Dial, Schematic_l
R1 D
(RTNG)
C
Page 4
Page 5
TABLE A
ISS 2, SECTION 501-165-117
, .
WIRE REMOVEFROM CONNECTTO
ORLEAD NET.TERM. NET. TERM.
COLOR
(W) -- GN
72-TYPE DIAL CONNECTIONS
(W-BL) -- S
(O-BK) -- C
72-Type (BK) -- RR
Dial (R) -- T
(BL) -- B
(R-G) -- R
(G) -- F
Line
Switch* (BR) C Dt
616-Type
Handset (R) T R
Cord (BK) B T
Jack
* In some telephone sets where this dial is used, this line switch
lead may be a different color.
t Dial terminal.
Page 5
5 Pages
Loading...