FIELD SERVICE BULLETIN NO. 5

Electrostatic Discharge and SBE 41 / 41CP CTD Sensors
November 2003; Updated August 2005

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Damage can occur if an electrostatic discharge is made to the titanium pressure port on Sea-Bird CTD-equipped ARGO floats manufactured prior to early 2004. The pressure sensor, and possibly the interface circuitry, can be damaged by ESD.

In early 2004, Sea-Bird installed transient surge protectors to help protect SBE 41 / 41CP CTDs from electrostatic discharge damage . However, large numbers of unprotected CTDs, manufactured before that date, remain at risk. Even after installation of  surge protectors, float manufacturers and end users should continue to observe good ESD-prevention practices, especially when handling unmounted CTD/endcap assemblies.

• The transient surge protectors are installed on SBE 41 with PCB assembly 40935Q and serial number 1415 and later; and SBE 41CP with PCB assembly 41015N and serial number 0796 and later.

Avoid wearing rubber-soled shoes. Avoid scuffing (sliding) your feet on carpeted surfaces. Discharge yourself by touching a grounded object.

Some examples of grounded objects include:

water faucet	computer chassis, especially the bare metal back panel
small screw that secures a wall switch or socket	ship's hull or steel deck

	1. Ground yourself.
	2. Then, grasp the float housing before touching the titanium pressure port.
	3. Finally, first grasp the float endcap and then touch the pressure port before and while making electrical or mechanical connections to the pressure port.

The CTD electronics and sensors should be treated like any unassembled semiconductor device:

• Avoid carpets in cool, dry areas. Leave PC cards in their anti-static packaging until ready to be installed.
• Dissipate static electricity before handling any system components (PC cards, sensors) by touching a grounded metal object (see above).
• If possible, use antistatic devices, such as wrist straps and floor mats.
• Always hold a PC card by its edges. Avoid touching the contacts and components on the card.

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