HP 5501A Operating And Service Manual page 106

The receiver enclosure is designed to meet NEMA-12 standards for industrial packages. The
receiver is mounted by its two aluminum end caps. Four plastic spacers (part of the end caps)
separate the receiver case from i t s mounting plate and allow full air circulation around the
receiver to carry away the heat it generates (nominally two watts). B y using Nylon mounting
screws, the entire receiver is electrically isolated from its mounting plates breaking any
ground loops. This can be important when there are large electrical transients in the dc
power lines or large ac ground currents running through a machine.
For additional information and schematics, refer to the 10780A Receiver Operating and Service
Manual.
3.13
10740A Coupler
The 10740A Coupler serves a s a housing and communications facility for the other electronic
modules of the Laser Transducer System. Figure 3-70 shows the- inputs and outputs to the dif-
ferent modules. Electrical interconection of the modules is provided by the 86-pin connectors
on the coupler's printed circuit backplane. The other system modules are plugged into the back-
plane connectors. Thecoupler has no internal power supplies, but supplies power to the modules
from external power supplies connected to a barrier strip on its rear panel. Three dc voltages
are required: +5V, +15V, and -15V. (The +15V i s required only if the 5510A Opt 010 Automatic
Compensator is used in placeof the 10756A Manual Compensator or if thesystem includes 10764B
Fast Pulse Converter.
airpry
D.f.
srrmn
Null
I
=-?=
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llmnwml
w=sunpc.
+IS
volt.
-15
volt.
T I 5 Roturn
+ I volt.
+5 Return
--
Figure
3-10.
70740A Caupler Backplane Signals
Numerical data is transferred between cards over a 28-bit parallel data bus on the coupler
backplane. Binary coding is used. A four-bit-wide bus carries decimal point position infor-
mation, and another four-bit bus carries error flags that indicate the existence of conditions
that might make the data invalid. Associated with the data, decimal point, and error flag lines
i s a status line called Binary Data Valid (BDAV).