
2 | nVent.com
TOOLS REQUIRED
• Phillips (cross-head) screwdriver (for power supply
boards, motherboard, and User Interface assembly)
• Small flat-head screwdriver (for power supply and
other terminal blocks)
• 9/32 in nut driver (for User Interface assembly)
• 7 mm nut driver or wrench (if removing enclosure door
to replace User Interface assembly)
PRECAUTIONS
Important: The TTDM is an electronic unit. When
replacing parts, take the following precautions to avoid
damage to its electronic components:
• Handle with care, avoid mechanical damage.
• Keep the electronics dry.
• If handling circuit boards, hold them by their edges to
avoid physical contact with electronic components.
• Avoid contamination with metal filings, liquids, or
other foreign matter.
Before disconnecting power to the TTDM
and replacing parts, alert any groups that
must respond to alarms signaled by the
TTDM (an emergency response team,
for example) that you will be working on
theunit.
SHOCK HAZARD: Disconnect power to
the TTDM before opening enclosure door.
Important: After replacing one or more
parts following these instructions, test the
module in accordance with the module’s
installation instructions
(H55471 for a TTDM or TTDM-NMM,
H56314 for a TTDM-SIM).
CAUTION: WARNING:
4-20 mA current transmitter board A
Sensor Interface board B
Relays C
Power supply boards and fuse D
1. Remove old 4-20 mA board from the TTDM.
Remove the 4-20 mA current transmitter board.
Grasp the circuit board by its edges and pull up from
the motherboard. Gently rocking the board left to right
5° to 10° may help release the connection.
2. Install the new 4-20 mA board.
Position the new 4-20 mA current transmitter board;
orient the board so its markings are right side up. Before
applying pressure to seat the board, take care to align
the connectors along the top and bottom edges of the
4-20 mA board with their mating connectors on the
motherboard
Ribbon cable E
Motherboard F
User Interface assembly G
References for other parts H
TABLE OF CONTENTS—Instructions for Replacement Parts
A. REPLACING THE TTDM 4-20 MA CURRENT TRANSMITTER BOARD (NOT IN TTDM-SIM)
Remove 4-20 mA board
Top view of 4-20 mA board
Connectors
Storage
Keep replacement parts in a dry place prior to installation
to avoid possible damage to electronic components.
7 User Interface board
(not in TTDM-SIM)
8 4-20 mA board
(not in TTDM-SIM)
9 Sensor Interface board
10 Motherboard
11 Power supply board
12 Fuse (200 mA, 250 V)
13 Power cable terminal block
14 Ground/earth stud
15 Fault relay cable plug and
socket (not in TTDM-SIM)
16 Leak relay cable plug and
socket (not in TTDM-SIM)
17 Service relay cable plug and
socket (not in TTDM-SIM)
18 4-20 mA port plug and
socket (not in TTDM-SIM)
19 RS-232/485 port plug and
socket (not in TTDM-SIM)
20 Sensor Interface plug
andsocket
21 RS-485 plug and socket for
SIM network (only for use in
TTDM-NMM and TTDM-SIM)
22 Ribbon cable
(not in TTDM-SIM)
25 Relays