Theory Of Operation - Racal Instruments 1260-100 Manual

1260-100/101 Adapt-a-Switch Carrier Module User Manual
Mezzanine PCB Assembly
The Mezzanine is built from the same bare PCB as the Bridge. The difference is in the
components installed. One schematic (P/N 435138,-001) covers both the Mezzanine and Bridge.
General
The Mezzanine PCB serves two functions. It connects +5V, +12V, and +24V power from the
VXIbus backplane to the 1260-100 backplane. It also connects the VXIbus backplane signals to
the Option-01T if it is installed.
Power Filtering
The power is filtered before reaching either the backplane or Option-01T. The fuses, F1 through
F3, are of the surface-mount type. The fuses used are as follows.
FUSE MANUFACTURER
F1 Wickmann USA, Inc.
F2 Wickmann USA, Inc.
F3 Wickmann USA, Inc.
Signal Connections
Connectors P1 and P2 connect to the VXIbus backplane. Connectors J1 and J2 connect to the
Option-01T.
The Option-01T accesses the VXI Local Bus via J2C (third row of connector J2). These signals go
through the zero-ohm resistors R7 through R18 before reaching P2. From P2, the local bus signals
go to the Bridge module, which uses them to interface the Option-01T to the plug-ins.
DIP switches S1 and S2 are not installed on the Mezzanine. Instead, resistors R7 through R18
make the equivalent connections instead.
If an Option-01T is not installed on the Mezzanine, then the Local Bus Jumper Assembly (P/N
405951) must be installed onto connector J2. The local bus signals from an external Option-01T

1260-100 THEORY OF OPERATION

MANUFACTURER'S
PART NUMBER
418 2100000
417 1315000
417 1315000
Appendix B
RATING RACAL PART
(AMPS) NUMBER
10 921545
3.15 921546
3.15 921546
B-1