Hitachi ATT-20 Installation, Operation, Troubleshooting

SM 6299

1000 Technology Drive, Pittsburgh, PA 15219

645 Russell Street, Batesburg, SC 29006

STS USA Part Numbers

N454052-3901

N454052-3906

ATT-20 Audio Track Transceiver

through

 Troubleshooting

 Installation

 Operation

ATT-20 Audio Track Transceiver

Proprietary Notice

This document and the information contained therein are confidential – the disclosure or other communication, copying, reproduction and any use whatsoever is forbidden without the written authorization of Hitachi Rail STS USA, Inc.

Important Notice

STS USA constantly strives to improve our products and keep our customers apprised of changes in technology. Following the recommendations contained in the attached service manual will provide our customers with optimum operational reliability. The data contained herein purports solely to describe the product, and does not create any warranties.

Within the scope of the attached manual, it is impossible to take into account every eventuality that may arise with technical equipment in service. Please consult an STS USA local sales representative in the event of any irregularities with our product.

STS USA expressly disclaims liability resulting from any improper handling or use of our equipment, even if these instructions contain no specific indication in this respect. We strongly recommend that only approved STS USA spare parts are used as replacements.

©

the written authorization of Hitachi Rail STS USA, Inc.

1000 Technology Drive, Pittsburgh, PA USA 15219-3120

645 Russell Street, Batesburg, SC 29006

sts.hitachirail.com

ATT-20 Audio Track Transceiver

0

April 1997

Initial issue

Revised to current template.

resolved.

Revised Figure 1-1 and Figure 6-1 to

Unit part numbers.

3

March 2019

Hitachi Rail STS Branding

Revision History

REV. DATE NATURE OF REVISION

Updated parts lists and drawings.

1.0 June 2008

2 December 2015

Incorporated ECO EE-1223 (2/00). Miscellaneous minor grammatical changes. Proof read comments

add R14 and label. Revised Table 6-4 and Figure 6-1 for items 126 and 127. Revised Table 6-5

to correct ATT-20

ATT-20 Audio Track Transceiver

Table of Contents

1. GENERAL INFORMATION ............................................................................................................... 1-1

1.1. Introduction ............................................................................................................................... 1-1

1.2. Physical Description ................................................................................................................. 1-1

1.3. Specifications ............................................................................................................................ 1-1

1.3.1. Power Requirements .................................................................................................... 1-1

1.3.2. Transceiver Characteristics .......................................................................................... 1-2

1.3.3. Receiver Characteristics ............................................................................................... 1-2

1.3.4. Miscellaneous ............................................................................................................... 1-3

2. APPLICATION, INSTALLATION, AND ADJUSTMENTS ................................................................ 2-1

2.1. General ..................................................................................................................................... 2-1

2.2. Shunt Mode Track Circuit Application ...................................................................................... 2-1

2.3. Series Mode Track Circuit Application ...................................................................................... 2-2

2.4. Terminal Connections ............................................................................................................... 2-3

2.5. Mounting Requirements ............................................................................................................ 2-3

2.6. General Considerations ............................................................................................................ 2-3

2.7. Shunt Mode Operation .............................................................................................................. 2-4

2.7.1. Shunt Mode Installation ................................................................................................ 2-4

2.7.2. Shunt Mode Adjustment ............................................................................................... 2-5

2.8. Series Mode Operation ............................................................................................................. 2-5

2.8.1. Series Mode Installation ............................................................................................... 2-6

2.8.2. Series Mode Adjustment without Cable Compensating PCB ....................................... 2-6

2.8.3. Series Mode Adjustment with Cable Compensating PCB ............................................ 2-7

2.9. Lightning Protection .................................................................................................................. 2-7

3. FUNCTIONAL DESCRIPTION .......................................................................................................... 3-1

3.1. General ..................................................................................................................................... 3-1

3.2. Shunt Mode Track Circuit ......................................................................................................... 3-1

3.3. Series Mode Track Circuit ........................................................................................................ 3-1

3.4. Detailed Circuit Description ...................................................................................................... 3-1

3.4.1. Transmitter .................................................................................................................... 3-1

3.4.2. Receiver ........................................................................................................................ 3-2

4. FIELD MAINTENANCE ..................................................................................................................... 4-1

4.1. General ..................................................................................................................................... 4-1

4.2. Test Equipment ......................................................................................................................... 4-1

4.3. General Checks ........................................................................................................................ 4-1

4.4. Shunt Mode Checks ................................................................................................................. 4-1

4.5. Series Mode Checks ................................................................................................................. 4-3

5. SHOP MAINTENANCE ..................................................................................................................... 5-1

6. PARTS LISTS .................................................................................................................................... 6-1

6.1. ATT-20 Audio Track Receiver Kits ........................................................................................... 6-1

ATT-20 Audio Track Transceiver

6.2. ATT-20 Audio Track Transceiver Units .................................................................................... 6-1

6.3. ATT-20 Audio Track Receiver Parts List .................................................................................. 6-2

6.4. Cable Compensating PCB Parts List ........................................................................................ 6-5

7. RAIL TEAM AND TECHNICAL SUPPORT ...................................................................................... 7-1

List of Figures

Figure 1-1. ATT-20 Dimensions ......................................................................................................... 1-3

Figure 2-1. Shunt Mode Track Circuit Application .............................................................................. 2-1

Figure 2-2. Series Mode Track Circuit Application ............................................................................. 2-2

Figure 2-3. Lightning Arrester and Surge Ripple Filter for Shunt Mode Application .......................... 2-9

Figure 2-4. Lightning Arrester and Surge Ripple Filter for Series Mode Application ....................... 2-10

Figure 3-1. Transmitter PCB Schematic Diagram .............................................................................. 3-3

Figure 3-2. Receiver PCB Schematic Diagram .................................................................................. 3-5

Figure 4-1. ATT-20 Test Circuit for Shunt Mode Application ............................................................. 4-2

Figure 4-2. ATT-20 Test Circuit for Series Mode Application ............................................................. 4-3

Figure 6-1. ATT-20 Parts Illustration .................................................................................................. 6-4

Figure 6-2. ATT-20 Wiring Diagram ................................................................................................... 6-5

Figure 6-3. Cable Compensating PCB Parts Layout and Schematic Diagram .................................. 6-6

List of Tables

Table 1-1. Adjacent Frequency Rejection ......................................................................................... 1-2

Table 2-1. Terminal Assignments...................................................................................................... 2-3

Table 2-2. Ring-by Parameters for 0.1 Ohm Shunting ...................................................................... 2-5

Table 2-3. Cable Length vs. Frequency ............................................................................................ 2-6

Table 6-1. ATT-20 Unit Kits ............................................................................................................... 6-1

Table 6-2. ATT-20 Unit (Only) ........................................................................................................... 6-1

Table 6-3. Miscellaneous Application Units ...................................................................................... 6-1

Table 6-4. ATT-20 Unit Parts List ...................................................................................................... 6-2

Table 6-5. ATT-20 Part Tabulation .................................................................................................... 6-3

Table 6-6. Cable Compensating PCB Parts List ............................................................................... 6-5

ATT-20 Audio Track Transceiver

1. GENERAL INFORMATION

1.1. Introduction

This manual provides application, installation and maintenance information for the STS USA Audio Track Transceiver, Model ATT-20.

The ATT-20 is a short-range transceiver operating in the audio frequency range of 12 to 20 KHz. The high frequency range was chosen to provide sharp block definition. The ATT-20 can be used in applications such as highway crossings, island circuits, switch lock release and general train detection in non-electrified and DC electrified territories. In most cases, insulated joints are not required and track circuits up to 300 feet in length can be realized. Units are available for operation in either shunt mode or series mode applications.

1.2. Physical Description

The ATT-20 is a single unit transceiver containing separate transmitter and receiver printed circuit boards, mounted on a common chassis. The chassis is housed in a sheet metal box. The top cover of the unit is the faceplate to which Association of American Railroads (AAR) terminal posts are mounted.

1.3. Specifications

1.3.1. Power Requirements

Power Supply Voltage: 9.8 - 15.2 VDC Maximum Ripple: 1 Vpp Load Current: 600 mA. Fuse: 3 / 4 Amp fast blow

ATT-20 Audio Track Transceiver

1.3.2. Transceiver Characteristics

CAUTION

The ATT-20 may be operated from a constant potential rectifier (CPR) supply, batteries floating on a CPR, or an electronically regulated supply. Regardless of the supply used, a surge ripple filter (STS USA N451590-0301) must be used between the supply and the ATT-20 Transceiver.

Shunt Mode Output Voltage: 1.0 Vrms (modulated) into a 5-ohm load Series Mode Output Voltage: 0.25 Vrms (modulated) into a 1-ohm load Available Operating Frequencies: 12.28 KHz, 15.0 KHz, 20 KHz. Carrier Frequency Tolerance: + 0.5 % Modulation Frequency (All Units): 390 Hz + 0.5% Harmonic Output: -30 dB at second harmonic with 12 ohm load in shunt mode 7 ohm shunt mode; 1 ohm series mode

1.3.3. Receiver Characteristics

Sensitivity: 70 mVrms (modulated signal) + 14 mV Input Impedance: 7 ohms shunt mode, 1 ohm series mode Output Voltage: 7.65 VDC into 400 ohms

Table 1-1. Adjacent Frequency Rejection

ATT-20 Frequency

(KHZ)

12.28 15.0 -18.0

15.0

20.0

Adjacent Frequency of

Concern (KHz)

12.28

18.0*

20.0

15.0

18.0*

Rejection of Adjacent

Frequency (dB)

* Of concern where joint detectors are used.

-30.0

-21.0

-27.0

-44.0

-23.0

ATT-20 Audio Track Transceiver

RCV

(REF)

2

AUDIO TRACK

TRANSCEIVER

MODEL,ATT-20

(REF)

LOWER

6 1/16

2 1/8

8

+

RE LAY

-

(REF)

TL5

TL6

SHUNT

MODE

UNIT

2 1/4 (REF)

PC.NO. SER.NO. FREQ. RE V.

7 5/8

4

5

8

7

(REF)

+

BAT TE RY

-

XMT

1

4 5/8

(REF)

9 /41

3

RE LAY VO LTS

TL1

RAISE

(REF)

6

TL2

TL3

TL4

3B3.0001.01

R14

1.3.4. Miscellaneous

Reverse battery protection: Built-in Operating temperature range: - 40°C to +70°C Maximum block length: 300 ft. shunt mode at 3 ohm/1000 ft. ballast; 150 ft.

series mode at 3 ohms/1000 ft. ballast.

Recommended Relay: PN-150B, 400 ohm coil, (STS USA N322500-

701) Overall Dimensions: Refer to Figure 1-1. Mounting Hole Dimensions: 2¼" x 8½" Weight: 4 lbs., 14 oz. Terminal Connections: AAR

Figure 1-1. ATT-20 Dimensions

ATT-20 Audio Track Transceiver

300 FEET

MAX.

RING-BY

USSP-21

1

2

3

4

TO

BATTERY

1

2

3

4

5

6

7

8

TWISTED PAIR

ATT-2 0

HARD-WIRE SHUNT

USED DURING

SET-UP

3B3.0002.01

2. APPLICATION, INSTALLATION, AND ADJUSTMENTS

2.1. General

This section provides information on the application of the ATT-20, as well as installation and adjustment procedures for the ATT-20 and related equipment. It is also critical that this section be read in its entirety prior to any application considerations.

2.2. Shunt Mode Track Circuit Application

In this application, the transmitter output and receiver input are connected by cable directly to the rails. The connection is made through surge protectors by twisted line pairs as shown in Figure 2-1. The point at which the transmitter wires are connected

defines one end of the track circuit. While the other end of the track circuit is defined by

the receiver connections to the track. The receiver detects the presence of a train by the loss of the audio frequency signal that is shunted away by the train axle.

The shunt mode of operation is defined as a vital application.

Figure 2-1. Shunt Mode Track Circuit Application

ATT-20 Audio Track Transceiver

75 FEET

60 FEET

ADJUSTMENT

SHUNT

“O”

OHM SHUNT

USSP-21

_

+

TWISTED PAIR

ATT-20

1

2

3

4

12V

BATTERY

1

3

5 7

2 4 6

8

1

L1

T1

T2 T3

CT

C1 2

CABLE COMPENSATING PCB

3B3.0003.

00

2.3. Series Mode Track Circuit Application

In this application, the transmitter and receiver are wired in sequence via a jumper on the ATT-20 unit. This jumper connects transmitter output terminal 4 to the receiver input terminal 6. The remaining transmitter output lead (terminal 3) and the remaining receiver lead (terminal 5) are twisted as a pair and each is connected to its respective rail (see Figure 2-2). The presence of a train axle across the rails completes the series signal path, thus detecting the approach of a train.

The series mode of operation is a non-vital application.

Figure 2-2. Series Mode Track Circuit Application

ATT-20 Audio Track Transceiver

2.4. Terminal Connections

AAR type terminals are located on the top of the unit for making external connections. Refer to Table 2-1 for terminal assignments.

Table 2-1. Terminal Assignments

Terminal No. Description

1 + Battery

2 - Battery

3 Transmitter Lead

4 Transmitter Lead

5 Receiver Lead

6 Receiver Lead

7 + Relay

8 - Relay

Internal wiring is accessed through a hole with a grommet around it in the faceplate. Also located on the faceplate is an access hole which is intended for setting transmitter gain. This is a simple adjustment and can be accomplished with a screwdriver.

2.5. Mounting Requirements

A convenient mounting bracket, which is an integral part of the case, provides four holes spaced 2-1/4 x 8-1/2 apart to facilitate wall, shelf or rack mounting.

2.6. General Considerations

• Track leads to the transmitter and receiver must be a #9 AWG or heavier twisted pair.

• Power supply must be 9.8 - 15.2 VDC and capable of supplying 1 ampere. A surge ripple filter (STS USA Part No. N451590-0301) must be used between any supply and the ATT-20. Power supply ripples must not exceed 1.0 Vpp.

• Use higher frequency units when less ring-by is desired.

• Provide lightning protection per Section 2.9.

• The relay recommended to be used with ATT-20 is a vital PN-150B, STS USA

No. N322500-701, 400 ohm, plug-in type.

ATT-20 Audio Track Transceiver

2.7. Shunt Mode Operation

CAUTION

When using the shunt track circuit configuration, do not repeat the use of the same frequency unless circuits are isolated by at least two (2) insulated points.

Where less ring-by is desired, keep the track circuit length to a minimum and use the shortest possible track leads. Refer to Figure 2-1 and Table 2-2 for shunt track circuit application.

2.7.1. Shunt Mode Installation

Refer to Figure 2-1 and proceed as follows to install the ATT-20 in shunt mode application:

1. Connect transmitter terminals 3 and 4 to terminals 3 and 4 of the USS-21 surge suppressor. Continue the cabling to the track from terminals 1 and 2 of the USSP-21. Repeat the above procedure for cabling receiver input terminals 5 and 6 to the rails. All transmitter and receiver cables must be #9 AWG or heavier and used as a twisted pair. Ensure the combined lengths of the transmitter and receiver cables do not exceed 500 ft. Also, do not exceed block lengths of 300 ft.

2. Connect terminals 7 (relay +) and 8 (relay -) to the relay. The recommended relay to be used with the ATT-20 is a PN-150B, 400 ohm plug-in type, STS USA Part No.: N322500-701.

3. If the ATT-20 is to receive its DC power from a battery or constant potential rectifier supply (CPR) or an electronically regulated supply, a surge ripple filter (Part No. N451590-0301) must be used as follows:

a. Connect terminals 1 (+) and 2 (-) of the ATT-20 to respective "+DC" and "-

DC" terminals of the ripple filter. See Figure 2-3.

b. Jumper terminals 2 to N on the ripple filter and cable terminals B (positive)

and N (negative) to their respective battery bus or supply terminals. Lightning arrestor USG-A N451552-0101 should be across ripple filter terminals B and N. Refer to Section 5 for the details on lightning protection.

4. If the ATT-20 is to be powered from an electronic supply, this supply should be capable of delivering 1.0 ampere at 12 VDC (on the ATT-20 side of the surge ripple filter) and be dedicated to the ATT-20 that it is powering.

ATT-20 Audio Track Transceiver

12.28 KHZ

15.0 KHz

20.0 KHz

100

11

10

9

2.7.2. Shunt Mode Adjustment

Proceed as follows to adjust the ATT-20 in a shunt mode installation:

1. Connect a hard-wire shunt across the rails outside of the defined block at the desired ring-by distance from the ATT-20 receiver track connections (terminals 5 and 6). Table 2-2 shows typical ring-by parameters for 3.0 ohm/1000 ft. ballast and 0.1 ohm adjustment shunt.

Note

The adjustment shunt mentioned below is not a hard-wire shunt. The resistance of the adjustment shunt must accurately represent the desired shunting sensitivity.

2. Adjust the ATT-20 transmitter output level through the access hole in the top cover until the relay is energizes.

3. Remove the hard-wire shunt from the rails.

4. Place an adjustment shunt across the rails at the receiver connection (not the ring-by distance). The relay should deenergize. A compromise between the shunting sensitivity (adjustment shunt) and ring-by distance will be achieved per application.

5. Remove the adjustment shunt from the rails. The adjustment procedure is complete.

Table 2-2. Ring-by Parameters for 0.1 Ohm Shunting

Track Length

(Ft.)

100

200

300

Total Cable Length (Ft.)

300 14 14 13

500 19 19 19

200 18 18 17

300 21 21 22

500 29 29 33

300 30 30 33

400 35 36 41

500 40 43 52

Typical Minimum Ring-By (Ft.)

2.8. Series Mode Operation

Series track circuit locations operating at the same frequency must be separated by at least two insulated joints. A typical series mode application would be at a switch lock.

ATT-20 Audio Track Transceiver

-3904

12.28

< 75 feet

T3

-3905

15

< 50 feet

T2

2.8.1. Series Mode Installation

Refer to Figure 2-2 and proceed as follows to install the ATT-20 in a series mode application:

1. Connect a jumper strap between terminals 4 and 6 on the ATT-20 when the total single conductor cable length from the ATT-20 to the track is less what appears in Table 2-3 below. If the cable length is exceeded, connect terminals 4 and 6 on the ATT-20 to terminals 1 and 2, respectively, of the cable compensating circuit board (N131002-01). The cable compensating PCB is part of an ATT-20 kit. See Section 6.1 for part numbers.

Table 2-3. Cable Length vs. Frequency

Suffix No.

N451052-

-3906 20 < 25 feet T1

Frequency

(KHz)

Total Cable Length

(Length x 2 cond.)

Jumper from Cable Compensating

PCB to Terminal:

2. Connect terminals 3 and 5 to terminals 3 and 4 of the USSP-21 surge suppressor.

3. Connect terminals 1 and 2 of the USSP-21 to the track at a point 75 feet from the switch points. All cabling from the ATT-20 to the track must be #9 AWG or heavier twisted pair.

4. Connect terminals 7 (relay +) and 8 (relay -) to the relay. The recommended relay to be used with the ATT-20 is a PN-150B, 400 ohm, plug-in type, Part No. N322500-701.

5. If the ATT-20 is to receive its DC power from a battery, constant potential rectifier supply (CPR), or an electronically regulated supply, a surge ripple filter (Part No. N451590-0301) must be used as follows:

• If the ATT-20 is to be powered from an electronic supply, this supply should

be capable of delivering 1.0 ampere at 12 VDC (on the ATT-20 side of the surge ripple filter) and be dedicated to the ATT-20 it is powering.

2.8.2. Series Mode Adjustment without Cable Compensating PCB

Proceed as follows to adjust the ATT-20 in a series mode, without cable compensating PCB installation:

1. Connect a hardwire shunt across the rails 65 feet from the ATT-20 track connections.

2. Adjust the ATT-20 transmitter output level through the access hole in the top cover until the relay is just energized.

ATT-20 Audio Track Transceiver

3. Remove the hardwire shunt from the rails. The adjustment procedure is complete.

2.8.3. Series Mode Adjustment with Cable Compensating PCB

Proceed as follows to adjust the ATT-20 in a series mode, with cable compensating PCB installation:

1. Place a zero ohm shunt across the track connections at the feed end.

2. Connect an AC voltmeter (Vrms) across terminals 5 and 6 on the ATT-20.

3. On the cable compensating PC board, adjust the slug in pot core inductor L1 until the voltmeter indicates a maximum.

Note

Depending on cable length, peaking of the signal might not be possible. After adjustment of inductor, place a small amount of RTV in the pot core adjuster area.

4. Remove the zero ohm shunt.

5. Connect a hardwire shunt across the rails 65 feet from the ATT-20 track connections.

6. Adjust the ATT-20 transmitter output level through the access hole in the top cover until the relay is just energized.

7. Remove the hardwire shunt from the rails. The adjustment procedure is complete.

2.9. Lightning Protection

Block wiring diagrams showing the wiring of surge and ripple protection for the ATT-20 in both the shunt and series modes of operation appear in Figure 2-3 and Figure 2-4, respectively.

Two lightning protection devices are to be used with the ATT-20. The track connections will be made through a USSP-21 secondary surge protection and the battery power supply line will be protected by a surge ripple filter that uses a USG-A lightning arrester across the power bus terminals.

The USSP-21 surge protector is wired to permit line-to-line protection using a low voltage arrester and line-to-ground protection using high voltage arresters. Internal circuitry of the USSP-21 also includes series line inductors as well as back-to-back

ATT-20 Audio Track Transceiver

Zener diodes for suppression of low voltage transients. The STS USA part no. is N451552-0525.

The surge ripple filter consists of a series line inductor and a four-terminal capacitor with a selenium suppressor diode across its terminals. The four-terminal capacitor guarantees loss of power to the load should one of the capacitor leads or plates open.

The line-to-line arresters used across terminals 1 and 2 of the USSP-21 and terminals B and N of the Surge Ripple Filter are USG-A N451552-0101.

The line-to-ground arresters used across terminals 1 and 5, 2 and 6 of the USSP-21are USG-A N451552-0201.

ATT-20 Audio Track Transceiver

TO

TRACK

1

2

5

6

3

4

USSP-21

TO

TRACK

1

2

5

6

3

4

USSP-21

3 4

TRANSMITTER

5

6

RECEIVER

ATT-2 0

+

_

DC

RE LAY

1

2

7 8

SURGE RIPPLE

FILTER

(N451590-0301)

4 2

B N

LIGHTNING ARRESTER PART NO. N451552-0101

TO

BATTERY

OR POWER SUPPLY

TWISTED PAIR

3B3.0004.01

Figure 2-3. Lightning Arrester and Surge Ripple Filter for Shunt Mode

Application

TO

TRACK

1

2

5

8

USSP-21

3

4

3

4

6

5

TRANSMITTER

RECEIVER

ATT-20

1 2

7

8

+ DC

_

DC

+

_

RE L AY

TWISTED PAIR

+

_

DC

4

B

N

2

TO

BATTERY

OR POWER SUPPLY

LIGHTNING ARRESTER PART NO. N451552-0101

3B3.0005.01

ATT-20 Audio Track Transceiver

Figure 2-4. Lightning Arrester and Surge Ripple Filter for Series Mode

Application

ATT-20 Audio Track Transceiver

3. FUNCTIONAL DESCRIPTION

3.1. General

The transmitter produces an output signal in the high audio frequency range and is sine wave modulated to provide noise immunity. First, the receiver detects the modulation information signal. It then amplifies and rectifies this signal to provide a DC output which drives the relay coil. The functional description of the ATT-20 applied to the shunt track circuit is covered in Section 3.2. Section 3.3 covers the series mode track circuit.

3.2. Shunt Mode Track Circuit

As illustrated in Figure 2-1, the transmitter output and receiver input are cabled directly to the rails. The point at which the transmitter wires are connected defines one end of the track circuit. The other end of the track circuit is defined by the receiver connections to the track. The receiver detects the presence of a train by the loss of the audio frequency signal which is shunted away by the train axle.

The shunt mode of operation is defined as a vital application.

3.3. Series Mode Track Circuit

As illustrated in Figure 2-2, the transmitter and receiver are wired in series via a jumper located on the ATT-20 unit. This jumper connects the transmitter output terminal to the receiver input terminal. The remaining transmitter output lead and the remaining receiver lead are twisted as a pair with each is connected to its respective rail. The presence of a train axle across the rails completes the series signal path, thus detecting the presence of a train

The series mode of operation is a non-vital application.

3.4. Detailed Circuit Description

3.4.1. Transmitter

The transmitter circuit diagram is shown in Figure 3-1. Transistor Q1 and its associated circuitry comprise the modulation oscillator which produces 390 Hz. A constant signal level is maintained by Zener diode D1. Transistor Q2 buffers the modulation oscillator.

Transistor Q7 and its associated circuitry comprise the carrier frequency oscillator. Selection of capacitor C3 determines the carrier frequency.

Transistors Q3, R8 and R13 mix the carrier and modulation signals. Resistor R14 provides gain control. Inductor L1, capacitor C5, and resistor R17 form a bandpass filter which allows the modulated carrier to pass unaltered by low frequency or higher order harmonic disturbances.

ATT-20 Audio Track Transceiver

Resistor R15 and R19 form a voltage divider which sets the bias for transistor Q4. Capacitor C12 bypasses resistor R19. Transistors Q4, Q5, Q6 and Q8 make up a unity gain amplifier with low output impedance. Diodes D4, D5, D6 and D8 - along with resistors R20 and R21 - serve to temperature compensate and bias both transistors Q5 and Q6. C13 is a bypass capacitor. Capacitor C6 and the primary of T3 couple the signal to the output circuitry.

Inductor L5, jumper J2 and capacitor C9 from the shunt mode output, provide an output impedance of 7 ohms.

Inductor L6, jumper J1 and capacitor C9 form the series mode output provide an output impedance of 1 ohm.

Diode D7 prevents damage from reverse battery connection. Fuse F1 prevents damage from an overcurrent condition. Inductors L2, L3 and capacitor C11 provide RFI rejection. Capacitors C7 and C10 filter the power bus.

3.4.2. Receiver

The receiver circuit diagram is shown in Figure 3-2. Capacitor C1, transformer T1 and resistor R1 form a medium Q input filter. Jumper positions should be J1 and J3 for both shunt and series mode boards. The input impedance is primarily determined by R1 (Shunt boards = 7 ohms, series boards = 1 ohm). Transistors Q1 and Q2 form a Darlington pair emitter follower which buffers the input signal. Resistor R4 and Zener diode D10 provide a fixed bias voltage for Q1 and Q2.

Inductors L3 and L4; capacitor C3, C4 and C5; and resistors R6 and R7, together form a high Q bandpass filter. Diode D1 demonstrates the signal. Resistor R8 and capacitor C6 filter the carrier frequency. Transistor Q3 and its associated circuitry form an emitter follower to buffer the demodulated signal. Resistor R13 is selected to provide an input sensitivity of 70 mVrms (modulated signal).

Transformer T2 and capacitor C9 form the demodulated filter. Transistors Q4 and Q5 are con-figured as an emitter follower which buffers the demodulated signal. Capacitors C11 and C12, along with diode D3 and D4, form a voltage doubler. This doubler produces a negative DC voltage which drives a level detector.

The level detector consists of resistor R17 and diode D5. Once in conduction, D5 provides the feedback path necessary for Q6 and its associated circuitry to behave as an oscillator. The oscillator frequency is approximately 25 KHz. The output of the oscillator is buffered by transistor Q7 and Q10. Transistors Q8 and Q9 amplify the signal. Diodes D7 and Q11, along with capacitors C17 and C8, form a voltage doubler. They also rectify and filter the signal to provide a negative DC voltage to drive an external relay. The Q11 circuit decreases relay drop away time in lieu of the standard 2diode voltage doubler circuit. Inductors L1, L2, L6, and L7 (along with capacitors C19 and C7) provide RFI rejection. Capacitor C10 filters the power bus.

ATT-20 Audio Track Transceiver

15T

R20

D8

2N60 59

Q5

2N227 0

Q8

100uf

C6

0.5

R21

0.5

2N6052

Q6

D6

R18

470

D5

TL6

C9

.47uf

SHUNT

COMJ1

J2

SERIES

.47uf

L5

C8

T3

6T

26T

L6

TP5

GND

TL4

L2

B-

TL3

T2

2N 3117

820K

R2

1K

VSK130

D7

.01uf

C11

TP4

L3

Q4

.22uf

R6

C1

1.0uf

+

R15 1K

L1

1K

1328T

LVA4 50

D1

390K

R3

C13

3.0K

R19

1N9 14

1N914

10K

R16

TP3

C4

1M

R14

3 3K

R13

1N914

D3

TP1

3.6M

R22

470K

R12

TAB .

C3

10K

R8

2N3964

Q7

R7

10K

258T

26T

.15u f

C2

8.2K

R11

10K

R5

5.1K

R4

5 .1K

3.3K

R9

R1 0

Q1

T1

R1

332T

D2 1N914

TAB .

6.8uf

10K

R23

C5

TAB.

R17

1N914

2N 3117

47uf

C12

2N 3117

Q3

2N 3117

Q2

TP2

TL2

POWE R

1- 1/2 A

F1

TL1

B+

1N9 14

TRACK

TL5

TRACK

47uf

C7

.01uf

C10

D4

3B3.0010.

00

Figure 3-1. Transmitter PCB Schematic Diagram

ATT-20 Audio Track Transceiver

C

20K

R24

R17

A

C19

R1

J2

.01uf

J1TAB

TL1

B

T1

TAB .

TA B

1ST

2N4037

Q11

6.8uf

1N4003

L4

TP6

R7

TAB

TA B.

TP2

TA B.

100

R5

TBD

D10

2N2270

1N4003

2N 3117

Q1

D9

R2

LVA462

Q2

R6 C3 C4

680

.027uf

C16

2ND1ST

T3

2N 311 7

Q6

300

R23

10K

R22

C

TP4

TL6

1.5K E16CA

L7

D11

L6

2N 311 7

Q7

TRACK

1.5K

T2

R15

1K

R14

TBD

R13

2N 3117

Q3

10K

R12

Q4

47uf

C10

47K

R11

.0033uf

TAB .

C5

1N4936

+

5uf .01uf

C7R32KC18

D1 C8 R10

D2

1K

1N914

C

D4

1N4003

POWER

+

C12 10uf

TL3

B

A

.02uf

C6

TAB

TAB .

L3

TP1

C15 .1uf

R21

2.4K

10K

R4

2ND

J4

J3

R20

L2

TL2

C1L1

Q10

24K

R25

2K

R26

20

R28

VSK130

D7

680

2N4037

R27

Q9

+

C17

2N3053

Q8

D6

2N2270

TP5

C11

+

2N2270

Q5

B

RE L AY -

200K

R8

.56uf

C14

270K

R19

.027uf

C13

2K

GND

TL4TL5

1.8K

RE LAY +

D5

LVA 45 0

240K

R18

2N 3117

1ST

C9

.15uf

2ND

10uf

R16 100 1N4003

TP3

D3

3B3.0009.00

ATT-20 Audio Track Transceiver

Figure 3-2. Receiver PCB Schematic Diagram

ATT-20 Audio Track Transceiver

4. FIELD MAINTENANCE

4.1. General

The following procedures may be used to check the ATT-20 at its field installation. These procedures should also reveal whether the fault is in the ATT-20 or a related unit or circuit. If fault lies with the ATT-20, the ATT-20 should be replaced with a new unit. When installing the new unit, please make certain to follow all installation procedures outlined in Section 2. Replacement units may be obtained through the STS USA Sales Office.

4.2. Test Equipment

• True RMS reading DMM (Fluke 8010A or equivalent).

• 5.0 ohm, 5 watt resistor 1%

• 1.0 ohm, 5 watt resistor 1%

4.3. General Checks

Proceed as follows to perform a general check of the ATT-20 unit before performing a series mode or shunt mode check:

1. Inspect all leads for breaks and loose terminal connections.

2. Check power supply voltage at terminals 1 (+) and 2 (-). The voltage should be 12 VDC nominal (9.8 minimum to 15.8 VDC maximum). Ripple voltage should not exceed 1.0 Vpp.

3. Check the fuse on the transmitter circuit board. If it is open, replace it with a 3.4 Amp fast-blow fuse. If the fuse is intact, disconnect the transmitter and receiver track connections at the unit. To test for proper operation in the shunt mode, refer to Section 4.4. To test for proper operation in the series mode, refer to Section

4.5.

4.4. Shunt Mode Checks

Proceed as follows to perform a shunt mode check:

1. Connect the ATT-20 as shown in Figure 4-1.

2. Turn the RELAY VOLTS potentiometer fully clockwise. If the relay energizes, proceed to step 3. If the relay does not energize, check the relay connections for proper polarity and open circuits. If the same relay connections are good, replace the ATT-20 with one of a unit of the same operating frequency and repeat steps 1 and 2. If the relay still does not energize, replace it with another PN-150B, 400 ohm coil (STS USA Part No. N322500-701).

ATT-20 Audio Track Transceiver

12V

BATTERY

+

_

1

2

3

4

5

6

7

8

_

+

PN150B REL AY

1.0

OHM

5.0 OHM

ATT-20

3B3.0011.00

3. If the relay does energize, disconnect the resistor between terminals 3 and 5, and disconnect the jumper between terminals 4 and 6. Measure the open circuit voltage across terminals 3 and 4. The voltage should be equal to or greater than

2.3 Vrms. If this voltage should be equal to or greater than 2.3 Vrms, reconnect the resistor between terminals 3 and 5, and reconnect the jumper between terminals 4 and 6. Adjust the transmitter level so that it just energizes the relay. Measure the voltage across terminals 5 and 6 (receiver input). This voltage should be 70 mVrms + 14 mVrms. If not, replace the ATT-20 unit.

Figure 4-1. ATT-20 Test Circuit for Shunt Mode Application

The tests performed in Section 4.4 verify proper operation of the ATT-20 unit in a shunt mode application. If the track circuit installation still does not work properly, troubleshoot the cabling, connections, and peripheral equipment associated with the track circuit.

ATT-20 Audio Track Transceiver

12V

BATTERY

+

_

1

2

3

4

5

6

7

8

_

+

PN150B REL AY

1.0 OHM

ATT-20

3B3.0012.00

4.5. Series Mode Checks

Proceed as follows to perform a series mode check:

1. Connect the ATT-20 as shown in Figure 4-2.

2. Turn the RELAY VOLTS potentiometer fully clockwise. If the relay energizes, proceed to step 3. If the relay does not energize, check the relay connections for proper polarity and open circuits. If the relay connections are good, replace the ATT-20 with a unit of the same frequency and then repeat steps 1 and 2. If the relay still does not energize, replace the relay with another PN-150B, 400 ohm coil (STS USA Part No. N322500-701).

3. If the relay energizes, disconnect the resistor between terminals 3 and 5, and disconnect the jumper between terminals 4 and 6. Measure the open circuit voltage across terminals 3 and 4. This voltage should be greater than or equal to

0.4 Vrms. Replace the ATT-20 if the open circuit voltage is less than 0.4 Vrms. If the voltage is greater than or equal to 0.4 Vrms, reconnect the resistor between terminals 3 and 5, and reconnect the jumper between terminals 4 and 6. Adjust the transmitter level to just energize the relay. Measure the voltage across terminals 5 and 6 (receiver input). This voltage should be 70 mVrms + 14 mVrms. If not, replace the ATT-20 unit.

The tests performed in Section 4.5 verify proper operation of the ATT-20 unit in a series mode application. If the track circuit installation still does not work properly, troubleshoot the cabling, connections, and peripheral equipment associated with the track circuit.

Figure 4-2. ATT-20 Test Circuit for Series Mode Application

ATT-20 Audio Track Transceiver

5. SHOP MAINTENANCE

STS USA recommends that faulty ATT-20 units be returned to the factory for shop level testing and repair. Both the transmitter and receiver PCB’s must undergo special testing, calibration, and component replacement (per frequency) procedures. See Section 7 for contact information.

ATT-20 Audio Track Transceiver

Part No.

Frequency (KHz)

Application

Item

Part Number

Application

6. PARTS LISTS

6.1. ATT-20 Audio Track Receiver Kits

Each kit consists of a complete ATT-20 unit for series mode application and the Cable Compensating PCB. Table 6-1 lists the kit part numbers.

Table 6-1. ATT-20 Unit Kits

Kit Part No, ATT-20 Unit Cable Compensating PCB Application

X451052-3907 N451052-3904 N13100201 Series

X451052-3908 N451052-3905 N13100201 Series

X451052-3909 N451052-3906 N13100201 Series

6.2. ATT-20 Audio Track Transceiver Units

The ATT-20 unit part numbers and descriptions are listed in Table 6-2. Table 6-3 lists other devices that are used in certain ATT-20 applications.

Table 6-2. ATT-20 Unit (Only)

N451052-3901 12.28 Shunt

N451052-3902 15.00 Shunt

N451052-3903 20.00 Shunt

N451052-3904 12.28 Series

N451052-3905 15.00 Series

N451052-3906 20.00 Series

Table 6-3. Miscellaneous Application Units

Secondary Surge Protector USSP-21

Surge Ripple Filter N451890-0301 Between ATT-20 power input and DC source

Lightning Arrestor N451552-0101 Across battery terminals of Surge Ripple Filter

Cable Compensating PCB N1310-0201

N451522-0525 Between ATT-20 unit and track

ATT-20 Audio Track Transceiver

Item

Part Number

Description

Quantity

6.3. ATT-20 Audio Track Receiver Parts List

Table 6-4 and Table 6-5 contain parts lists for ATT-20 Audio Track Transceiver units N451052-3901 through -3906. Refer to Figure 6-1 for the component locations. The internal wring diagram is shown in Figure 6-2.

Table 6-4. ATT-20 Unit Parts List

5 Refer to Table 6-5 CHASSIS 1 EA

10 R438872 COVER 1 EA

15 Refer to Table 6-5 PCB,ATT-20 TRANSMITTER 1 EA

20 Refer to Table 6-5 PCB,ATT-20 RECEIVER 1 EA

25 M181829 4 WAY BLOCK 1 EA

30 J5252720110 SCREW-10-32X5/8 SST 2 EA

35 J047733 WASHER,10 STEEL LOCK MED 2 EA

40 J048172 NUT,10-32 HEX STEEL 2 EA

45 J047818 WASHER,17/64X9/16 COP 40 EA

50 J480300 NUT,14-24 HEX BRASS NP 16 EA

55 J480301 NUT,14-24 HEX BRASS 16 EA

60 J525111 SCREW,8-32X1-1/4 RD HD STEEL 4 EA

65 J047714 WASHER-8 SHPRF LK SS 4 EA

70 J048166 NUT,8-32 HEX STEEL 4 EA

75 M337854 INS TUBING 8 EA

80 J052686 SCREW,8X3/8 RD HD 4 EA

85 J730041 TERM-PRE-INSUL, DIAGR 8 EA

90 (not shown) J078399 BAG-PLASTIC,#60F-0406 1 EA

100 (not shown) S705.11 WIRE, TAG 12" BUNDLE 1 EA

105 J075415 GROMMET, RUBBER 3/8"ID 1 EA

110 (not shown) A774169 TUBING.HT SHRINK 3/16ID 1 FT

115 (not shown) A774184 TUBING SHRINK FIT 1/16 1 FT

120 (not shown) A434083 CA-1 TW. PR. SHELDD. MIN 6 FT

125 J703310 CABLE TIE, SELF LOCKING 5 EA

126 J0759550056 LABEL, WHITE, POLY, #M-787, OILTAK 1 EA

127 J7928220039 RIBBON, THERMAL TRANSFER, R6007 1 EA

ATT-20 Audio Track Transceiver

CHASSIS

Item 5

XMITTER PCB

Item 15

RCVR PCB

Item 20

Table 6-5. ATT-20 Part Tabulation

ATT-20 Unit Freq. (KHz) Application

N451052-3901 12.28 Shunt R451053-6302 N451605-6402 N451605-6502

N451052-3902 15 Shunt R451053-6302 N451605-6403 N451605-6503

N451052-3903 20 Shunt R451053-6302 N451605-6404 N451605-6504

N451052-3904 12.28 Series R451053-6303 N451605-6405 N451605-6505

N451052-3905 15 Series R451053-6303 N451605-6406 N451605-6506

N451052-3906 20 Series R451053-6303 N451605-6407 N451605-6507

ATT-20 Audio Track Transceiver

5

RCV

COMP. SIDE

2

AUDIO TRACK

TRANSCEIVER

MODEL,ATT-20

LOWER

+

RE LAY

-

TL5

COMP. SIDE

TL6

R14

SHUNT

MODE

UNIT

15

PC.NO. SER.NO. FREQ. RE V.

4

5

8

7

40

+

BAT TERY

-

XMT

1

75

65

70

60

30

20

3

35

RELAY VOLTS

TL1

RAISE

6

10

80

TL2

TL3

TL4

25

85

45

55

50

3B3.0006.01

TL6

TL5

Figure 6-1. ATT-20 Parts Illustration

ATT-20 Audio Track Transceiver

B

SHIELD

R

B-

B+

SHIELD

TL1

TL3

TL6

TL5

TL2

TL4

TRACK

POWER

GND

R

B

R

B

XMITER PCB

RCVR PCB

RE LAY +

RE LAY -

1

2

3

456

7

8

3B3.0007.00

Item

Part No.

Description

Quantity

Figure 6-2. ATT-20 Wiring Diagram

6.4. Cable Compensating PCB Parts List

Refer to Table 6-6 and Figure 6-3 for Cable Compensating PCB, STS USA N13100201, parts, parts layout, and schematic diagram.

Table 6-6. Cable Compensating PCB Parts List

5 N381621 BLOCK, TERM 1 EA

10 N13100101 PCB, CABLE COMPEN 1 EA

15 J047818 WASHER,17/64X9/16 COP 2 EA

20 J5000970128 SCR-SST 1/4-20X1-3/4 2 EA

25 J4751200112 WASHER, SST PLATE NO1/4 2 EA

30 J4751210111 WASHER, SST LOCK NO1/4 2 EA

35 J4802110108 NUT,1/4-20 SST HEX 2 EA

ATT-20 Audio Track Transceiver

10

15

5

20

30

25

35

3B3.0008.00

Figure 6-3. Cable Compensating PCB Parts Layout and Schematic Diagram

ATT-20 Audio Track Transceiver

7. RAIL TEAM AND TECHNICAL SUPPORT

The Rapid Action Information Link Team (RAIL Team) is a group of experienced product and application engineers ready to assist you to resolve any technical issues concerning this product. Contact the RAIL Team in the United States at 1-800-652-7276 or by e-mail at [email protected].

ATT-20 Audio Track Transceiver

End of Manual