MCi JH-400B Series Technical Manual page 55

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A.
B.
A relay rack of equipment counts as a single unit and
should be connected to a single ground wire going to the
System Ground. DO NOT "DAISY CHAIN" separate racks.
Make ALL shield connections FIRST--leaving chassis ground
wires disconnected until the following tests have been
completed:
Be sure that all power plugs are DISCONNECTED.
With an OHMMETER, test the resistance between each chassis
in the system. You should find a high resistance between
all units.
1HIS HIGH RESASTANCE READING IS YOUR BEST ASSURANCE AGAINST
l
GROUND LOOPS
I
C. Plug in the power cables.
IF
your 3rd wire is a satisfactory
ground, and IF all units have a 3rd wire power cable, then
your grounding system is complete.
NOTE: Using the 3rd wire grounding system breaks the FIRST rule of
grounding. The 3rd wire usually goes from one plug to another--
so that EACH PIECE OF APPARATUS does not have a separate ground
wire going straight back to the system ground.
V,
IF EXCESSIVE NOISE--OR GROUND LOOPS--ARE PRESENT IN YOUR SYSTEM
WHEN USING THE 3RD WIRE GROUND, REMOVE THE 3RD WIRE GROUNDS.
The single exception to
supply for the Console.
power transformer which
be most
effe~tive.
You
required by most codes.
the above instruction is the Audio power
This supply has a Faraday shield in the
must connect directly to the 3rd wire to
may use this point as the 3rd wire ground
A jumper is provided between the power supply common and the frame
of the supply to make it possible to "float" the low voltage
audio supply if necessary.
CAUTION:
DO NOT OPERATE ANY PART OF THE SYSTEM WITH
GROUNDS REMOVED,
CONNECT A GROUND WIRE TO
EACH
CHASSIS (OR EACH RACK)
MAKING SURE THAT EACH WIRE IS CONNECTED DIRECTLY
TO THE SYSTEM GROUND,
BE
VERY SURE
THAT THE SYSTEM GROUND IS CONNECTED
TO A WATER PIPE OR A GROUNDING STAKE,
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