JRC JMA-3400 Series Instruction Manual page 21

PRECAUTIONS
The USB ports prepared on the front panel side and the back panel side are
limited to a maximum of 500 [mA] based on the USB 2.0 standard.
If a device with a current consumption exceeding 500 [mA] is connected to
this port for the purpose of charging electronic devices, etc., the current limit
circuit may operate and the USB port may be temporarily unavailable.
Do not insert chart cards and data SD cards other than properly arranged
new pec/Navionics+ into the CHART card slot.
If the display unit infects with a computer virus via SD card, it may affect other
equipment and cause a malfunction.
The waterproof performance of the display unit is IPX5. For the operating
conditions to guarantee this performance, refer to the integrated display unit
waterproofing specification in Chapter 12 of this manual.
If the operating conditions are not observed, the waterproof performance is
not guaranteed and may cause fire, electric shock, or failure.
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