Two years ago when I searched the net for a "Sea and sea ysd2 strobe problems" topic, what I found was minor production complaints. Now there are many topics on this subject.
In my case, I purchased 2 new YSD2 strobes and on the first dives they seemed to work ok. They are connected with fiber optic cables to my Nexus housing, and working on a Nikon d800. After a while I realized that the output of the strobes were not the same. I changed the batteries ( the problem could not be the batteries since the strobe would not fire if there wasn't enough power), I switched the fiber optic cables (the problem could not be the cables since the strobe would not fire if it was not triggered by the camera). Nothing has changed. The funny thing was that the strobes looked perfect , they both fired but the outputs were not the same.
I took them back to the local distributor here in Turkey, they checked the strobes, both above and under water on a sea and sea housing, with their own cables but they were not able to see the problem. I kept on insisting, and show them my photos . What they did was they lend me one of their own flashes to be used on my next trip to Los Jardenias de la Reina - Cuba.
With five (3 seanadsea ysd2 and 2 inon z240) flashes I went to Cuba. Nothing has changed, neither mine nor their extra flash had the same output. Since I have two housings I had to use the only working strobe to save the trip. On my last day when I was packing the strobes I took the diffuser off the working strobe, I was shocked - since there were black and gray smoke residue inside the strobe but the strobe was working fine. It was not flooded nor over used the flash tube simply produced smoke. When I checked my second strobe which did not have the same output as the first one, the tube was ok, but the temporary strobe given by the distributor had the same burn marks. Just like the attached photo I found on the internet.
My conclusion :
1-some of the Sea and Sea ysd2 strobes has problems with their flash tubes although they fire.
2-one of my flashes had an electronic board/circuit problem that stopped it from firing with the desired or calculated output.
What happened next : I took the flashes back to the distributor, they saw and realized the problems , and they sent the flashes back to Japan with a very long letter explaining Sea and Sea what I ve been thru. After 2 months of waiting they replaced my strobes with new ones ,but this time they are yellow (not black). Probably S&S has been aware of the matter and started to ship newly produced strobes and mine are from the new batch.
I am very pleased and happy with the Turkish distributor's service but I am done with Sea and Sea.