GE
D
IRECTION
FQ091019, R
EVISION
2
V
IVID Q
N S
ERVICE
M
ANUAL
Chapter 2 - Site Preparations
2-5
The following table lists recommendations for preventing EMI:
2-2-7
Probe Environmental Requirements
NOTE:
System and electronic probes are designed for storage temperatures of -20
o
to +50
o
C. When
exposed to large temperature variations, the probes should be kept at room temperature for a
minimum of
10 hours
before use.
Table 2-5
EMI Prevention/ Abatement
EMI Rule
Details
Ground the unit.
Poor grounding is the most likely reason an ultrasound unit will have noisy images.
Check the grounding of the power cord and power outlet.
Be aware of RF sources.
Keep the unit at least 5m (16.4 ft) away from other EMI sources. Special shielding may
be required to eliminate interference problems caused by high frequency, high powered
radio or video broadcast signals.
Replace and/or reassemble
all screws, RF gaskets,
covers and cores.
After you finish repairing or updating the system, replace all covers and tighten all
screws. Any cable with an external connection requires a magnet wrap at each end.
Install the shield over the front of the card cage. Loose or missing covers or RF gaskets
allow radio frequencies to interfere with the ultrasound signals.
Replace broken RF gaskets.
If more than 20% or a pair of the fingers on an RF gasket are broken, replace the gasket.
Do not turn ON the unit until any loose metallic part is removed and replaced, if required.
Do not place labels where
RF gaskets touch metal.
Never place a label where RF gaskets meet the unit. Otherwise, the gap created will
permit RF leakage. In case a label has been found in such a location, move the label to
a different, appropriate location.
Use GE-specified harnesses
and peripherals.
The interconnect cables are grounded and require ferrite beads and other shielding.
Cable length, material, and routing are all important; do not make any changes that do
not meet all specifications.
Take care with cellular
phones.
Cellular phones may transmit a 5 V/m signal that causes image artifacts.
Properly address peripheral
cables.
Do not allow cables to lie across the top of the system. Loop any peripheral cable excess
length into one bundle.
Table 2-6
Probe Operation and Storage Temperatures
Electronics
Operation
10 — 40
o
C (50 — 104
o
F)
Storage
-10 — 60
o
C
(14 — 140
o
F)
