VR3 4th cell and I/O Connector O-ring

daveroo

Dear All

Since installing the APV fourth cell and hooking it up to my VR3 (7pin, software v3.03), I have not enjoyed much success. The whole shabang calibrates perfectly, and runs fine underwater for about 10-15mins, at which point the VR3 pO2 begins to creep up, while the handsets stay constant. I have tried swapping out cells, I have tried different brands of cells. I have even built an extension cable so that the fourth cell could live inside the head (I had the quaint idea that the development of temperature gradients across the fourth cell could make it creep up). I still get the same behaviour. All my contacts are nice an shiny. The only thing I did notice was a few beads of moisture on the ouer bore of the I/O connector on the VR3, but certainly no evidence that moisture was getting in to the contacts.

Apparently the I/O connector on the VR3 has an O-ring in its base. However, when I look down into the connector, I can see what looks like a groove, but if it is o-ring it's not obvious to my feeble eyes. I guess it must be there, otherwise I'd have green cludge where my contacts used to be.

Question: How obvious is the o-ring inside the I/O connector, what spec is the o-ring, and how does one go about changing it?

Also any other insights into this problem would be welcome.

Thanks and regards

Daveroo