23
Installing The TBUS Coax Cable
The throttle bus - called the TBUS - must be in the form of a single linear run of cable. Do not
create any T's or Y's unless they are less than 12 inches long.
Never use any cable-TV splitters or similar accessories. They won’t work and may damage the
Extender
R17
U2
V1
Extender
h
First Plate Second Plate Last Plate
Terminator
Resistor
Coaxial Cable
RG58 or RG59
Terminator Resistor
At the end of the cable run, attach the 75 ohm terminator resistor that came with the Extender. The
easiest location to put the resistors is on the last fascia plate circuit board.
Note: Do not use the terminator resistor if you are using the Wireless Receiver at the end of the
line. It has a built in terminator which may be switched on. For more information, see the RX904
Wireless Receiver instruction booklet .
Attaching the terminator to the last plate at the end of the bus run is easy. This resistor is included
with your extender board. Solder the resistor at the location shown. Use the hole for one lead and
solder the other lead to the trace. Use plenty of solder Make sure leads are firmly soldered to the
traces. Note: the terminating resistor is hot to the touch which is normal.
Throttle Bus Testing
Attach the modular cable to the Command Station Throttle Jack and connect to the input jack on
the Extender. Apply power. The green LED will be on and the red LED will be off. If the red LED
is ON, you have a short circuit in your TBUS wiring. Check and correct before proceeding.
Finding Throttle Bus Shorts
Starting at the far end of the cable run, disconnect the fascia plate from the bus cable and check
the red LED. If it's still on, reconnect the cable and move to the next plate. Work backwards
toward the extender board, disconnecting each section of cable until the red LED turns off. Once
it does, you should be holding the cable with the problem. Redo the twist-on connector at each
end since it's the most likely cause of the problem.
OK - No T’s or Y’s
1st Plate
Last Plate
Not Allowed
“T”
“Y”
TBUS Signal
Back of Fascia Circuit Board
75 ohm
Terminator
Resistor
TBUS Ground
Connect to earth ground
for static protection
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