BT Redcare 3GSTU-12V Troubleshooting guide

User/Installation Guide
3G STU
LPS 1277: Issue 3
Cert No. 1270a

CE MARKING
The STU* carries the CE approval marking in accordance with the CE Marking Directive
93/68/EEC. The STU complies with the following European Directives:-
73/23/EEC (Low Voltage Directives)
by compliance with safety specifications:-
EN60950 User Safety
EN41003 Network Safety
89/336/EEC (Electro Magnetic Compatibility Directive) as amended by 92/31/EEC
by compliance with EMC specifications:-
EN55022 Emissions Class B
EN50130-4 Immunity
99/5/EEC (Radio and Telecommunications Terminal Equipment Directive)
EN 50131-1 (Security grade 4, Environmental class 1)
* STU = Subscriber Terminal Unit

Table of Contents
INTRODUCTION 4
Scope 4
Static Sensitive Devices 4
Decommissioning Procedure 4
3GSTU OVERVIEW 5
Specifications 7
Safety 8
Power Supply 8
Compatibility 8
REN 8
INSTALLATION 9
Training Courses 10
Pre-Installation Requirements . 10
Connecting the Telephone Line and Earth 11
Mains Fail 12
Tamper 12
Power Connection 12
Alarm Inputs 13
Output Relays 14
Control Output 14
Return Path Signalling Output (RPS) 14
Line Fault Output 15
Telephone Line Selection (LK1) 15
INSTALLING THE NVM 16
Pin Alarm Polarity 17
Programming The NVM 18
Input 19
Switch 20
Status Indicators 23
STU Status LED Meanings 23
SYSTEM COMMISSIONING 24
Testing the System 24
Warranty 25
Repairs 25
TROUBLESHOOTING 26
Chirps 26
Equipment Compatibility Issues 26

Introduction

Page 4
Scope
This document is provided to support professional installation of the BT redcare range of STU products:
Model Description Part No.
3GSTU-12V 12 V supply, 8 pin alarms 46600-12V
3GSTU-24V 24 V supply, 8 pin alarms 46600-24V
3GSTU-PLI Plug-in 46600-PLI
11zstu 11 Zone, 11 pin alarms 46770
fire stu-24S 24 V fire stu, 3 pin alarms (Standard build) 46600-24S
fire stu-24A 24 V fire stu, 3 pin alarms (ADT) 46600-24A
fire stu-24C 24 V fire stu, 3 pin alarms (Chubb) 46600-24C
fire stu-24G 24 V fire stu, 3 pin alarms (Gardiner) 46600-24G
Static Sensitive Devices
Static electricity is present in our everyday lives. A static charge is generated by friction, and whenever two dissimilar
materials are separated. The imbalance of electrons causes a potential difference of many hundreds of volts. On discharge,
a large current flows for a short time.
Many electronic components can be damaged by such static charges. Component failure may not be immediate or
catastrophic. Electro-Static Discharge (ESD) can cause hidden damage to components, which will affect their reliability.
It is recommended that precautions are taken against damage due to static electricity during the installation and
maintenance of the STU. Suitable ESD protection measures include ensuring that you are earthed (via a wrist strap and a
1 MO resistor) whenever you handle the unit.
Decommissioning Procedure
Important:
If the STU is in service, the Alarm Receiving Centre (ARC) must be contacted to decommission it before it is power cycled.
You must follow these decommissioning instructions when there is a need to change the alarm system settings:
1. Call the ARC and request they decommission the STU.
2. Wait for the ARC to confirm that the STU is decommissioned.
3. Turn off the power to the alarm system completely (i.e. switch off the mains and disconnect the battery).
4. Make the desired changes to the alarm system.
5. Re-connect the battery and switch on the mains to re-apply power to the STU.
6. Request the ARC re-commission the STU.
7. Test the system (see page 24).

Page 5
3GSTU Overview
The 3GSTU is the Public Switched Telephone Network (PSTN) Subscriber Terminal Unit for the BT redcare service. It is
available in a number of variants:
3GSTU-12V
The 3GSTU-12V variant is a stand-alone unit for mounting inside an alarm panel or auxiliary cabinet. This variant requires
a 12 V d.c. supply. And has 8eight pin alarm terminals. The power supply, relay outputs and alarm inputs are connected
by means of hard wiring to the terminal blocks on the 3GSTU.
3GSTU-24V
Has the same functionality as the 3GSTU-12V but operates from a 24V d.c. supply.
Fire STU
Easily identified by the red plastics, the fire stu is a stand-alone unit for mounting inside an alarm panel or auxiliary
cabinet. This variant has only three pin alarm terminals and a fixed Hard-ID, it requires a 24 V d.c. supply. The fire stu is
intended for use in fire alarm applications that have standardised on a 24 V d.c. supply.

Page 6
3GSTU-PLI
The 3GSTU-PLI variant is a plug-in unit for mounting onto certain alarm panel motherboards. With the exception of the
Return Path Signalling, all power supply, output and alarm input connections are made by two connectors that protrude
through the base.
The 3GSTU-PLI variant will fit the following alarm panels:
Scantronic 4700, 9100, 9600, 9800, (9500 II via adapter board).
Scantronic 808, 806, 840I
Castle Care-Tech 2300, 2500, 2700, 2900.
Modern Alarms 3000, 3200, 3400.
11zstu
The 11-Zone STU consists of a stand-alone base model 3GSTU with 8 alarm channels plus an expansion board that
provides connections for alarm inputs 9, 10 and 11. This expansion board also provides connection for AC Fail input.
(Note that it is NOT possible to add this board to an existing 3GSTU to expand the number of zones).

Page 7
Specifications
Power supply requirements:
3GSTU-12V, 11zstu
Voltage: 10 V DC to 15 V DC
Current: 160 mA mean @12 V DC (For standby battery capacity)
Ripple/noise: 200 mV p-p max. (40 mA typical, all relays de-energised)
Low battery threshold (detected by 3GSTU-12V): 10.8 V ± 0.2 V
3GSTU-24V, fire stu
Voltage: 20 V DC to 28 V DC
Current: 160 mA max, (40 mA typ, all relays de-energised)
Ripple/noise: 200 mV p-p max
Low battery threshold (detected by 3GSTU-24x): 22.2 V ± 0.2 V
The 3GSTU-PLI variant supply requirements are:
12V Supply Voltage: 10 V DC to 15 V DC.
12V Supply Current: 80 mA typ
12V Supply Ripple/noise: 200 mV p-p max
5V Supply Voltage: 4.75 V DC to 5.25V DC
5V Supply Current: 30 mA typ
5V Supply Ripple/noise: 50 mV p-p max
Pin alarm inputs:
Logic High = +3.5 V to +30 V
Logic Low = -0.5 V to +0.8 V
Logic level outputs: (on sockets SK1 and SK2)
Logic High = 3.8 V @ 560 μA max
Logic Low = 0.4 V @ 280 μA max
These voltages are with respect to the 0V terminal on TB3
Relay contacts:
30 V, 1 A Max
Physical:
Size = 168 x 115 x 36 mm
Mass = 250 g
Environmental:
Operating ambient temperature +5° C to +40° C

Page 8
Safety
The circuit board area, under the cover, is classed as a Telecommunication Network Voltage (TNV-3) circuit. All other
interconnection points are classed as Safety Extra-Low Voltage (SELV) circuits. It is only necessary for this cover to be
removed during installation of the PSTN wiring.
The host alarm panel or box into which the STU is installed must provide a RESTRICTED ACCESS LOCATION and a FIRE
ENCLOSURE in accordance with the requirements of BS EN 60950.
It is essential that the STU is installed so that there is a gap of at least 5 mm between it and any other part of the host
equipment (excluding the mounting face and plug-in connectors). If any part of the host apparatus uses or generates
voltages in excess of 250 V rms or dc, obtain advice from a competent telecommunications safety engineer before you
install the STU.
Power Supply
The STU must be connected to a suitable power supply. The installer must ensure that the rating of the power supply is
greater than the combined rating of the STU and any other apparatus drawing power from the power supply.
The STU supply requirements are detailed on page 7.
Compatibility
The STU is designed for connection to either the Public Switched Telephone Network (PSTN) or a Private Wire
(RedDIRECT). It is also compatible with earth calling lines.
It is NOT to be used with 1+1 carrier systems or a shared service.
The STU must NOT share a telephone line with other electronic data equipment, such as a facsimile machine, EPOS
terminal or digital communicator unless a redcare Modem Compatibility Device (MCD) is used. (MCD cannot be used with
Private wire or Earth Calling lines.)
Only one STU may be connected to any one telephone line.
REN
The Ringer Equivalence Number (REN) for the STU is 1. As a guide to the number of apparatus that can be simultaneously
connected to a line, the sum of REN values for each apparatus should not exceed 4.0. A BT provided telephone is
assumed to have a REN value of 1.0 unless otherwise marked. If the STU is used with an MCD, the combined REN will be
1½.

Installation