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Theory of Operation
3- 6
TLA721 Benchtop & TLA7XM Expansion Mainframe Service Manual
The power supply connects to the backplane at J1 and J2 through the power
supply interface board.
The backplane (A4) provides all the connections to module slots 0 through 12 in
the chassis. It also has connections to all other circuit boards and modules in the
chassis.
The front panel On/Standby DC switch connects to one of two connectors at the
top of the backplane. When the switch is connected to J22, the switch controls
the power in the chassis. When the switch is connected to J23, the power-on
functions are controlled by an external source through the 25-pin connector on
the enhanced monitor board. Although the switch still illuminates when power is
applied to the chassis, the on/off function of the switch is disabled.
A 34-wide ribbon cable at 0J4 on the backplane connects to J16 on the tempera-
ture sense board. Connectors 0J1, 0J2, and 0P3 carry instrument monitoring
information from the backplane to the enhanced monitor board.
The enhanced monitor board (A3) collects the monitoring information from the
power supply, blower, and temperature sense board and passes the information to
the 25-pin D connector. The enhanced monitor board connects directly to the
backplane at 0J3, 0P1 and 0P2.
The 25-pin D passive monitor connector lets you monitor the power supply
voltages, blower speed, and the maximum slot temperature rise within the
chassis. The connector also provides remote on and off capability and access to
the SYSRESET* and ACFAIL* signals.
CAUTION.
Do not connect an RS-232 cable to the 25-pin connector. This 25-pin
connector is not an RS-232 port.
Connecting an RS-232 cable to this connector might result in damage to the
equipment.
The universal fan controller on the enhanced monitor board drives the EBM/
PAPST fan pulse with modulation (PWM) speed control input.
The blower (fan assembly) consists of a chassis mount, rear fan cover, and
EBM/PAPST fan. The fan is a low-noise, high-airflow design that supports up to
308 CFM of airflow through the mainframe at full speed. The blower connects to
the enhanced monitor board at FAN 1/Blower (J8). The fan speed switch (S1)
lets you select either variable fan speed (VAR) or full speed (FULL).
Backplane
Enhanced Monitor Board
Blower
Summary of Contents for TLA7XM
Page 5: ......
Page 13: ...Table of Contents viii TLA721 Benchtop TLA7XM Expansion Mainframe Service Manual ...
Page 17: ...Service Safety Summary xii TLA721 Benchtop TLA7XM Expansion Mainframe Service Manual ...
Page 21: ...Preface xvi TLA721 Benchtop TLA7XM Expansion Mainframe Service Manual ...
Page 25: ...Introduction xx TLA721 Benchtop TLA7XM Expansion Mainframe Service Manual ...
Page 43: ...Specifications 1 18 TLA721 Benchtop TLA7XM Expansion Mainframe Service Manual ...
Page 85: ......
Page 87: ...Adjustment Procedures 5 2 TLA721 Benchtop TLA7XM Expansion Mainframe Service Manual ...
Page 161: ...Repackaging Instructions 6 74 TLA721 Benchtop TLA7XM Expansion Mainframe Service Manual ...
Page 165: ...Electrical Parts List 8 2 TLA721 Benchtop TLA7XM Expansion Mainframe Service Manual ...
Page 169: ...Diagrams 9 4 TLA721 Benchtop TLA7XM Expansion Mainframe Service Manual ...
Page 189: ...Mechanical Parts List 10 20 TLA721 Benchtop TLA7XM Expansion Mainframe Service Manual ...