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

Page 10
Training Courses
BT redcare offer a free training course for installers of the redcare service. For further information call General Enquiries
Tel: [phone]
Pre-Installation Requirements
Before a STU installation can commence, a BT redcare Service Order must be submitted to BT redcare by the Alarm
Receiving Centre. This ensures that the appropriate exchange connections have been made and a redcare block terminal
92A has been provided at the customer’s premises.
To enable an NVM to be programmed the following information is required:
a) The variant of STU is to be connected (-12V, -24V, -PLI, 11 zone or fire)
b) The alarm channels required and the function to be assigned to each channel. The channels are typically assigned as
follows:
For intruder alarm systems
Channel 1 Fire Channel 5 Optional
Channel 2 Personal Attack Channel 6 Optional
Channel 3 Intruder Channel 7 Optional
Channel 4 Opening/Closing Channel 8 Engineer Test
For fire detection systems the fire stu has only three available channels which can be used as required.
c) The polarity of the alarm inputs, positive applied or positive removed. (Note: for a 3GSTU-PLI (plug-in) variant all alarm
inputs must be positive applied with the exception of alarm input 4 which must be positive removed).
d) The type of line connection, PSTN (normal telephone line) or a Private Wire (RedDIRECT)
e) The type of line monitoring function required
Important:
THE ALARM SYSTEM MUST BE TOTALLY POWERED DOWN (SWITCH OFF MAINS AND DISCONNECT THE BATTERY)
BEFORE INSTALLATION CAN COMMENCE.
For certain alarm panels, the 3GSTU-PLI can be directly mounted using the "Plug-in" connections available. Locate it on
the two 8-way connectors on the control panel circuit board. Take care to align the pins to the sockets on the board
correctly: if they are out of alignment, damage may occur.
For other alarm panels and installations where “Plug-in” connections are not available, the unit can be wired
“stand-alone”. Fix the STU to the inside of the control panel using the adhesive mounting pads provided after ensuring
that the control panel and STU base are free from dust or grease.
Care must be taken when connecting wires to the terminal blocks TB1,2,3,4 and TB5. The small screws can be easily
damaged by over-tightening. Wiring connected to terminal blocks should be kept as short as possible to reduce the
likelihood of radio frequency (RF) pickup.

Page 11
Connecting the Telephone Line and Earth
The TNV circuit cover of the STU should not be removed whilst the unit is connected to the PSTN or Private Wire network.
Remove the TNV circuit cover from the STU.
Use two core telephone cable (type: 1/0.5 mm CW1308) that is not yet connected to the PSTN or Private Wire (PW)
network. Strip back the insulation so that 5 mm of wire conductor is exposed. Position the cable in the plastic base as
shown on page 12. Connect one core to the terminal marked A and the other to the terminal marked B.
Strip back an earth cable (green/yellow, core area greater than 1mm²) so that 5mm of wire is exposed. Position the cable
in the plastic base as shown and connect it to the terminal marked
The other end of this cable must be connected to a good electrical earth.
Failure to fit an earth cable will prevent proper operation of the unit and will invalidate the warranty.
Replace the TNV circuit cover and secure in position with the screw.
Take the opposite end of the two core telephone cable and strip back both cores so that 5 mm of wire is exposed.
Connect both wires to the redcare block terminal.
WARNING: the block terminal contains telecommunication network voltages.
Please note that it is important to use the correct method of connecting the STU to the BT Block Terminal 92A. The Block
Terminal provides an insulation displacement connection (IDC) block for the incoming phone line. No connections, other
than those made by BT, should be made to this IDC block. The STU should be connected to the screw terminals as shown
on page 12.

Page 12
Mains Fail
If an AC fail signal is provided from the power supply, this can be connected to one of the pin alarm input terminals. For
11 Zone STU connect this to TB1-12, in this case the AC fail alarm will not be indicated on the STU status LED.
Tamper
If a tamper signal is provided this can be connected to one of the pin alarm input terminals. The tamper alarm can also be
generated and sent to the ARC if the STU itself detects a tamper, such as the removal of the NVM.
Power Connection
As stated at the beginning of the Installation section, the power supply must be totally powered down (switch off mains
and disconnect the battery) before making these connections.
For 3GSTU-12V units, connect a 12 V DC power supply to TB3. Connect +12V to the terminal labelled V+ and 0V to the
terminal labelled 0V.
For 3GSTU-24V and fire stu units, connect a 24 V DC power supply to TB3. Connect +24V to the terminal labelled V+
and 0V to the terminal labelled 0V.
If the STU is to be powered from a separate power supply, the “0V” terminal on TB3 must be connected to the alarm
panel common (0V) and the PSU 0V.
For 3GSTU-PLI units, power supply connections are made automatically when it is plugged in to the host alarm panel.

Page 13
For stand alone units, alarm inputs must be connected to the alarm panel outputs. An eight way (three way for –24V)
terminal block (TB1) is provided for connection of the alarm inputs.
For 11zstu, alarm inputs for channels 9, 10, 11 and AC Fail are made at the terminal block TB1 on the expansion board.
Connections for alarm inputs 9, 10, 11 and AC Fail are made to terminals marked 9 though 12 of TB1 respectively. The
connections are made in exactly the same way as for alarm inputs 1 to 8.
Alarm Inputs
For plug-in units, connections to the alarm panel are made by the two connectors which protrude through the base.
When fitting the unit, check that SK1 pins 1 to 8 and SK2 pins 9 to 16 correspond to pins 1 to 8 and 9 to 16 on the
alarm panel.
The signal present on each pin is as follows:
SK1 Function SK2 Function
Pin 1 Alarm Input 1 Pin 9 +12V
Pin 2 Alarm Input 2 Pin 10 0V
Pin 3 Alarm Input 3 Pin 11 Not Used
Pin 4 Alarm Input 4 Pin 12 +5V
Pin 5 Alarm Input 5 or 7 (see below) Pin 13 Not Used
Pin 6 Control Output Pin 14 Alarm Input 6
Pin 7 Not Used Pin 15 Line Fault (output)
Pin 8 Low battery (input) Pin 16 Alarm Input 8
Alarm 5 can be transmitted as either channel 5 or channel 7. This is achieved by fitting LK2 in either position 5 or 7. This
link is not fitted on the stand alone units, as alarms 5 and 7 can be transmitted independently.

Page 14
For panels which provide relay contact outputs, the common of each relay should be connected to an A+ terminal (TB2)
on the STU. Either the normally open or normally closed contact should be connected to the relevant STU alarm input
(TB1). For example, if the relay is energised in the alarm state, connect the relay Normally Open contact to TB1 for a
positive applied alarm or connect the relay Normally Closed contact to TB1 for a positive removed alarm. Note: The A+
terminal provides four 10KO pull up resistors to V+. If more than four are required extra 10KO resistors should be
connected, one end to V+ and the other to the relay common.
For panels which provide voltage outputs, each alarm signal should be connected directly to the relevant STU alarm input
terminal (TB1).
Un-programmed channels can be left unconnected. If any channels have been enabled in the NVM, but are unused,
these should be connected the ‘No Alarm’ state. The ‘No Alarm’ state will be 0V for Positive Applied inputs and +12V
(or V+) for positive removed inputs. This will prevent alarms being generated on the unused channels.
Output Relays
Three output relays are provided: Control, Return Path Signalling (RPS), and Line Fault. The use of any, or all, of these
functions is optional. For a basic installation these outputs are not required.
Note: If an output is to be connected to a device which produces transient voltages, such as a bell, the device should be
suppressed using a suitable protection diode.
Control Output
The Control Output is a general purpose output which is controlled by the Alarm Receiving Centre. It may be used for
various functions including the remote resetting of alarm panels.
The ‘Control Output’ relay contacts (Normally Open, Common, Normally Closed) are available for connection on terminal
block TB4. The relay contacts have a maximum current rating of 1 Amp.
For plug-in installations, Control Output connections are made automatically when the unit is fitted in the host alarm
panel. The host alarm panel must be programmed to enable this function (TELL BACK).
Return Path Signalling Output (RPS)
The RPS output is used to indicate, at the protected premises, that the opening/closing signal has been sent to and
acknowledged by the Alarm Receiving Centre.
To use the RPS function, one of the alarm inputs must be designated as an opening/closing channel (usually channel 4).
The RPS output will activate when an opening or closing signal is detected. It will de-activate when the opening or
closing signal has been acknowledged by the Alarm Receiving Centre. It is allowable to have more than one input
designated as an opening/closing channel, but each must be acknowledged to de-activate the RPS output.
The RPS relay contacts (Normally Open, Common, Normally Closed) are available for connection on terminal block TB4.
To use this option, a warning device such as a piezo bleeper or external strobe light should be connected as shown below.
The maximum current rating of the relay contacts is 1 Amp.

Page 15
Line Fault Output
The Line Fault output is used to indicate, at the protected premises, that there is a fault with the telephone line and/or
communications with the redcare system have been lost.
For stand alone units, the ‘Line Fault’ relay contacts (Normally Open, Common, Normally Closed) are available for
connection on TB4. The maximum current rating of the relay contacts is 1.0 Amps.
For 3GSTU-PLI units, Line Fault connections are made automatically when it is fitted into the host alarm panel. The host
panel must be programmed to accept this function.
The STU provides two different modes of local line monitoring, which can be selected when the NVM is programmed.
The ARC must be notified if local line monitoring is to be enabled, and if so, which mode is required.
For STUs connected to normal phone lines, ‘PSTN mode’ should be used. This mode monitors the DC line voltage and
triggers the Line Fault output within 100 seconds of a line break.
For STUs connected to private wires (RedDIRECT), ‘Private Wire mode’ should be used. This mode causes regular ‘chirps’ on
the line and triggers the Line Fault output within 3 minutes of a line break.
In both PSTN and Private Wire modes, the Line Fault output will be triggered within 40 seconds if the STU has an alarm
to transmit but cannot communicate with the redcare system.
Telephone Line Selection (LK1)
The STU is supplied ready to connect to the Public Switched Telephone Network (LK1 is not fitted). If the STU is to be
connected to a Private Wire (RedDIRECT) a suitable link must be fitted in the position marked LK1. An NVM chip must be
configured for PW use and fitted in accordance with the procedure on page 17.
If you have any doubts about the type of telephone line to which the STU is being connected, contact BT redcare for
advice.

Installing the NVM

Page 17
Installing The NVM
The NVM (Non-Volatile Memory) chip is a device used by the STU to store configurable parameters. This memory is
retained even when the power is completely removed.
There is a socket provided (at IC2) for the fitting of a pre-programmed NVM. Suitable NVMs for use with the STU are
National Semiconductor NM93C46N or Microchip Technology 93C46/P.
The NVM can be supplied pre-programmed by the ARC or the NVM can be manually programmed using a Scantronic
7200 NVM programmer (version 1.2 or 1.3 software) or a Scantronic 7300 NVM programmer (version 1.3 software).
Once fitted, the NVM can be re-programmed after careful removal using an IC extractor. If the unit has already been
commissioned, see the note on page 4. The STU and alarm system must be totally powered down (switch off mains power
and disconnect the battery) before fitting or removing the NVM.
Note the orientation of the device shown below and make sure it is fitted the correct way around.
Pin Alarm Polarity
The pin alarm channels respond to the voltage level at the terminal block inputs (stand-alone mode) or the pins of SK1
and SK2 (plug-in mode). The appropriate terminal block inputs and plug-in connector socket pins are tracked together in
parallel on the circuit board. Each channel can be programmed to be "Positive Applied" or "Positive Removed". This polarity
is set in the NVM.

Page 18
Programming The NVM
For 11zstu, the NVM programming does not affect the functions of alarm channels 9, 10, 11 and AC Fail. The extra
alarm inputs are configured by DIP switches on the expansion board. All unused alarm inputs must be disabled. For all
enabled alarm inputs, the correct polarity must be selected. Alarm inputs 9, 10 11 and AC Fail cannot be selected as
opening/closing channels.
Switches at SW1 are used to enable or disable and to select the polarity of the extra alarm inputs. The function of each
switch is indicated in the table below.
Input Switch Off On
9 1 Negative Applied Positive Applied
2 Disabled Enabled
10 3 Negative Applied Positive Applied
4 Disabled Enabled
11 5 Negative Applied Positive Applied
6 Disabled Enabled
AC Fail 7 Negative Applied Positive Applied
8 Disabled Enabled
Remote Programming
Once installed, the NVM can be re-programmed remotely by the ARC. Only the relay states can be adjusted unless a
technician is on-site to set the STU into Secure Access Mode using LK3. Remote NVM programming is not available on
the 11zstu or on older units that do not have LK3 fitted. Contact BT redcare for more information.
Manual Programming
NVMs can be programmed using a Scantronic 7200 or 7300 NVM programmer.
Apply power to the programmer (12 V DC or 12 V AC.) and set the on/off switch to position "0".
Insert the NVM in the socket marked ‘COPY NVM’. Ensure that the dot on the NVM lines up with the white dot on the
programmer.
Set the on/off switch to position ‘1’ and wait for the programmer to display its version information and follow the
instructions below:

Page 19
V1.3
# 001957
Press and the screen displays:
MASTER NONE
COPY 9314/C46
Press and the screen displays:
SIMPLE 8400,8440,9056 PROGRAMMING
Press once, or twice for 7300, until the screen displays:
READ/MODIFY COPY SOCKET DATA
Press and the screen displays:
YES
YES
YES
No