Model 935A
Dual Tone Sender
INSTRUCTION MANUAL
Monroe Electronics
100 Housel Ave Lyndonville NY 14098
800-821-6001 585-765-2254 fax 585-765-9330
monroe-electronics.com
Printed in USA Copyright Monroe Electronics, Inc.
Specifications subject to change without notice
P/N 1340020
7/20/04
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TABLE OF CONTENTS
Warranty Page 3
General Description Page 4
Installation Page 5
Theory of Operation Page 6
Operation and Adjustment Page 7
Figure 1 – Barrier strip Page 8
Figure 2 – 935A Block Diagram Page 9
Figure 3 – Cover/Push buttons Page 10
Figure 4 – 3223B-2 Page 11
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WARRANTY
Monroe Electronics, Inc. warrants to the owners, each instrument and sub-assembly
manufactured by them to be free from defects in material and workmanship for a period of
one year after shipment from factory. This warranty is applicable to the original purchaser
only.
Liability under this warranty is limited to service, adjustment or replacement of defective parts
(other than fuses or batteries) on any instrument or sub-assembly returned to the factory for
this purpose, transportation charges prepaid.
This warranty does not apply to instruments or sub-assemblies subjected to abuse, abnormal
operating conditions, or unauthorized repair or modification.
Since Monroe Electronics, Inc. has no control over conditions of use, no warranty is made, or
implied as to the suitability of our product for the customer's intended use.
THE WARRANTY SET FORTH IN THIS ARTICLE IS EXCLUSIVE AND IN LIEU OF ALL
OTHER WARRANTIES AND REPRESENTATIONS, EXPRESS, IMPLIED OR STATUTORY
INCLUDING, BUT NOT LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY
AND FITNESS. Except for obligations expressly undertaken by Monroe Electronics, in this
warranty, Owner hereby waives and releases all rights, claims and remedies with respect to
any and all warranties, express, implied or statutory (including without limitation, the implied
warranties of merchantability and fitness), and including but without being limited to any
obligation of Monroe Electronics with respect to incidental or consequential damages, or
damages for loss of use. No agreement or understanding varying or extending the warranty
will be binding upon Monroe Electronics unless in writing signed by a duly authorized
representative of Monroe Electronics.
In the event of a breach of the foregoing warranty, the liability of Monroe Electronics shall be
limited to repairing or replacing the non-conforming goods and/or defective work, and in
accordance with the foregoing, Monroe Electronics shall not be liable for any other damages,
either direct or consequential.
RETURN POLICY TO FACTORY
Materials returned to Monroe must have a Return Material Authorization number. To obtain a
RMA number, contact our A/V Switching & Control Customer Service at 585-765-2254 or fax
585-765-9330. Customers have 30 days to determine that the product ordered fills their need
and performs as described in Monroe’s literature. Units returned for approved repair or
credit, must be in the original packaging including all parts and paperwork plus be in very
good physical condition. If not, the customer is billed the cost to refurbish the unit and for
missing accessories and merchandise. No products may be returned for exchange or credit
after 12 months of the shipment date. Monroe reserves the right to repair or replace units
under warranty.
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GENERAL DESCRIPTION
Purpose of Equipment:
The model 935A Dual Tone Sender is a preprogrammed dual tone (TouchTone) encoder. It is intended to generate cue tone sequences to be
transmitted with satellite CATV audio to provide automated control of various
receiver and switching functions at CATV receiver sites.
Description of Equipment:
The Model 935A is supplied in a wall mount enclosure measuring
approximately 6 ½ inches long, 3 ¾ inches wide and 2 ½ inches deep. A wall
mount transformer / power supply is furnished with the 935A.
Four pushbutton switches are provided to select the proper code sequence
to be transmitted.
An eight-terminal barrier strip, accessible by removing the enclosure cover,
provides terminal connections for the power supply, audio output and remote
selection of tones.
Up to two four-digit “on-off” code sequences can be provided. The code
sequences may be altered by changing the plug-in memory in the Model
935A.
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INSTALLATION
General:
An eight-terminal barrier strip is provided for making the necessary
connections to the Model 935A, refer to Figure 1 on page 8.
Installation:
1. Remove the two screws holding the cover on the 935A enclosure.
Refer to figure 3 on page 10.
2. Carefully remove the cover; the four pushbutton switches on the
cover are attached to the terminal strip by an eight-inch wire
harness allowing the cover to be placed to one side of the base for
access to the terminals.
3. Connect a two-wire audio cable of required length across terminals
7 and 8 and attach the other end to the input of your mixer or other
appropriate input to allow the 935A output to place the cue tone
audio on your program audio.
Remote Installation:
The Model 935A may be operated by external equipment providing
relay closures controlled by timers or remote switchers.
Terminals 1 through 4 on the barrier strip provide connections to
duplicate the functions of the four pushbutton switches.
The following connections will be required:
To Control Connect Normally Open
Switch Number: Relay Contact Across:
1 1 and 5
2 2 and 5
3 3 and 5
4 4 and 5
The remote equipment will now control the operation of the 935A. The
pushbutton switches can still be used for local control if required.
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General:
The Model 935A Dual Tone Sender contains a Model 3223B Encoder
Controller and a Model 3171B Dual Tone Encoder both powered by
the wall mount power supply provided with the instrument.
A block diagram of the 935A is provided in Figure 2 on page 9.
Theory Of Operation:
A contact closure at one of the four pushbutton switches on the 935A
causes the Model 3223B-2 Encoder Controller to provide the
programmable memory in the Model 3171B with a binary input
sequence. Any one of the four sequences is selected upon the
pressing of the specific push button.
Upon receiving the proper BCD input sequence, the memory supplies
the digital tone generator in the 3171B with a logic low for a row and a
column for each of the four digits in the programmed sequence.
The output of the digital tone generator, a series of four dual tone
digits, is amplified and connected to the 935A output terminals through
the output transformer.
THEORY OF OPERATION
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OPERATION AND ADJUSTMENT
General:
The Model 935A provides an audio output consisting of four dual tone digits
transmitted in a rapid burst. The code to be transmitted is selected by
pressing one of the four push buttons as indicated by the labels on the
cover.
Operation:
The push buttons, illustrated in Figure 3 on page 10, control the tone
sequence as listed below:
Switch Function
S1 (Red) Sequence A "OFF" Code
S2 (Black) Sequence A "ON" Code
S3 (Red) Sequence B "OFF" Code
S4 (Black) Sequence B "ON" Code
The desired tone sequence will automatically be sent when the proper push
button is pressed and released or when the controlling relay opens after
being closed if remote operation is being used.
Testing:
The 935A can be tested for proper installation by listening for the burst of
audio tones on the program audio when the proper button is pressed.
Cue Tone Level:
An oscilloscope may be connected across terminals 7 and 8 if off-the-air
testing is required. The audio burst will be detected by the oscilloscope each
time a button is pressed. The amplitude should be approximately -12 dB
(≈0.5Vp-p; ≈200mV rms). Adjust R3 on 3171B for this amplitude. Refer to
Figure 1 on page 8.
Cue Tone Transmission Rate:
The Cue Tone transmission rate may be adjusted for other than the factory
setting of 10Hz (50mSec first pulse width). The Model 3223B-2 (refer to
Figure 4 on page 11) has an on board adjustment, R11. Turning R11
clockwise will increase the transmission rate; 12.5Hz = 40mSec,
14.3Hz. = 35mSec first pulse width.
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R3 located on
Programmable
Memory
Terminal Function
1 Switch 1
2 Switch 2
3 Switch 3
4 Switch 4
5 Common
6 +12 VDC IN
7
8
Output
Audio
3171B pcb
Barrier Strip
as viewed from top of unit with cover removed
Figure 1
9
Audio Output
Pushbutton Switches
1
2
3
4
Model
3223B
Encoder
Controller
Model
3171B
Dual Tone
Encoder
12 VDC
Power
Supply
115 VAC
Model 935A Dual Tone Sender
Block Diagram
Figure 2
10
Remove screws,
S3 S4 S2
two places to lift off
cover
S1
Model 935A Dual Tone Sender
Cover Picture
Figure 3
11
R11
located on
3223B-2 pcb
3223B-2 Encoder Controller
Figure 4
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