Just like any other part of our dive gear, if you have a Fischer Connector, it needs ongoing maintenance. The main enemy of any electrical part that might be used underwater or in a moist environment is corrosion that can cause failures and/or give you inaccurate information. Fischer connectors seem to always get moisture trapped inside and will with time corrode the electrical pins & sockets turning them green. If you see green, you have corrosion that needs to be removed.
On the end of your cable you will usually have the male side (pin side) of the Fischer connector. The computer usually has the female (socket side) of the Fischer connector. The O-Ring seal that is suppose to keep the moisture out is located at the bottom of the inside of the female (socket) side of the connector mounted on the computer. There are two types of male Fischer Connectors, one with, and one without a locking ring.
Shearwater Fischer Connector with Locking Ring
The idea of the maintenance is very straightforward, you must not let moisture be present inside the Fischer connector for any extended period of time, and if you find any corrosion you must remove it. By checking for moisture often and coating the inside of the Fischer connector with food grade mineral oil, you will prevent the corrosion that so many people seem to complain about that creates problems.
The steps and idea behind the maintenance is very simple.
1) Before diving, inspect the Fischer connectors for corrosion, if any is noted then you need to remove it. Once the corrosion is removed, coat the insides of both ends of the Fischer connector with food grade mineral oil. Note, that Shearwater Petrel 3 and NERD 2 dive computers are both supplied with a mini bottle of mineral oil. If you require more, the suggested food grade mineral oil can be found in any pharmacy or drug store.
2) After diving, don't let your dive gear sit around for very long. Inspect the connectors for moisture, blow out with dry air and coat with mineral oil and store with the protective caps.
3) Once you have coated with mineral oil, let it drain to eliminate any excess oil. The protective caps will keep the moisture out, the mineral oil in and also protects the o-ring sealing surface on the male end of the connector.
To remove any corrosion, I recommend “DeoxIT Contact Cleaner” which can be found on Amazon. Any other type of high quality electrical corrosion remover would also work just fine. Once the corrosion is removed, I would flush out the connectors with an electrical contact cleaner and then re-coat with mineral oil. I have been maintaining my Fischer connectors for several years this way and have had no problems.
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Written By Curt McNamee
Curt McNamee is a former advanced open circuit tri-mix and CCR dive instructor, who opened the very first Shearwater Service Centre for North America. Curt embodies the spirit of the Shearwater motto to "really, really care about our customers" and has demonstrated this throughout his career. After 20 years with Shearwater, Curt finally retired from the company in 2024.
