GE GA000100, Service Manual

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GE H
EALTHCARE
D
IRECTION
GA091568, R
EVISION
5 VIVID E9 S
ERVICE
M
ANUAL
Chapter 2 - Site preparations 2 - 7
2-2-3 EMI limitations
Ultrasound machines are susceptible to Electromagnetic Interference (EMI) from radio frequencies,
magnetic fields, and transients in the air or wiring. They also generate EMI. The VIVID E9 complies with
limits as stated on the EMC label. However there is no guarantee that interference will not occur in a
particular installation.
Possible EMI sources should be identified before the unit is installed.
Electrical and electronic equipment may produce EMI unintentionally as the result of a defect. These
sources include:
• medical lasers,
• scanners,
• cauterizing guns,
• computers,
• monitors,
• fans,
• gel warmers,
• microwave ovens,
• light dimmers
• portable phones.
The presence of a broadcast station or broadcast van may also cause interference.
See Table 2-3 on page 2-7 for EMI Prevention tips.
Table 2-3 EMI prevention/abatement sheet 1 of 2
EMI RULE DETAILS
Be aware of RF sources
• Keep the unit at least 5 meters (15 feet) 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.
Ground the unit
• Poor grounding is the most likely reason a unit will have noisy images.
• Check grounding of the power cord and power outlet.
Install all screws, RF
gaskets, covers, 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 Card Rack Cover over the Card Rack.
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.
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. or, if a label has been found in such a position, move the label.
Use GE specified
harnesses and peripherals
• The interconnect cables are grounded and require ferrite beads and other shielding.
• Also, cable length, material, and routing are all important; do not change from what is
specified.
Take care with cellular
phones
Cellular phones may transmit a 5 V/m signal; that could cause image artifacts.