I posting this in this thread because it sounds like the same or similar problem.
- First Stage DA AquaMaster Locked Up? I think it's your high pressure seat. Just fixed a recent one and the problem was the seat.
- I had this happen with the first DA-AM I rebuilt about 3-4 years ago, ended up sending it in for repair but the tech found it to be working fine. assumed it was an assembly problem and I must have put it back together right before I sent it off for repair. I had heard about the high pressure diaphragm spring as a possible source and bought a new one to swap in. It was already working fine though, so I never knew for sure what the problem was.
- Update to March 2016... My friend Rich brought his new DA Aquamaster to Cozumel. We had done nothing more than to "service" the reg because it was so nicely preserved and it worked great when we put it on a tank. BUT, we had not tried it on a 3,000 psi tank. And when he hooked it up to a tank down in Cozumel, it locked up the first stage and would release no air to the second stage. We had to crank the yoke screw and blow an O-Ring to get it off the tank... Same exact problem as my DA-AM had 3-4 years ago.
- Since there never had been a definite solution, I was back to the drawing board. I swapped in springs, diaphragm, pins, mushroom tops, nozzle bodies... Thinking maybe something dimensional was the problem or something binding and not moving freely. Nothing worked.
- Then over night I couldn't stop thinking about it and I came to the conclusion that whatever the problem was, it had to be in the first stage nozzle. I took that all apart again and everything was assembled correctly and moving freely. So, I put it all together and hooked it up to a 3000 psi tank... Just the nozzle, with a yoke, and with the pin and mushroom top assembled into it. I pushed on the mushroom top and it compressed the high pressure seat normally... Just the way it is supposed to. But no air came out. Usually you can turn the pressure on and then off and then pressing the mushroom top will cause the trapped air to pop out with a sound like an O-ring blowing. How could the seat be moving and not open up the air flow?
- I concluded that the soft seat material was somehow staying sucked against the orifice even thought the seat body (metal part) was moving away from the orifice just the way it is supposed to.
- I quickly swapped in a different high pressure seat and tried the same test. POW! Pressing the mushroom top now opened the orifice perfectly and the air popped tight out. I did the test a few more times to be sure. Then I re-assembled the nozzle into the regulator, hooked it up to a 3000 psi tank, and it worked perfectly. Eureka! A definite cause and solution to the locked up DA-AM first stage.