How to restore a Scubapro D300, D350 & D400: Theory and Practice

[Angelo Farina]

Here are the initial posts as a series of PDF's, to make it easier to navigate.
I appreciate all your support.

EDIT: corrected Service Guide uploaded 11/27

Really a great job.
However this stuff confirms to me in the choice to stay away from the modern regs and to continue relying on my beloved SP 109 (upgraded to BA), which by comparison are truly simple to service.

 

[scrane]

Similar idea. Marked ITALY and SCUBAPRO and PAT. PEND.

 

[lexvil]

Really a great job.
However this stuff confirms to me in the choice to stay away from the modern regs and to continue relying on my beloved SP 109 (upgraded to BA), which by comparison are truly simple to service.

That’s kind of funny, the D’s being discussed are a long way from being “modern” the only modern D is the 420 and it’s performance is so good that I’ve all but given up on inline designs except as safe seconds. The 420 is very easy to service but it is more complicated than the things developed in the 60’s

I was also in the inline balanced camp for years and sat out the center balance poppet era, until now. The D420 is my preferred second stage it’s not dead simple but neither is it’s performance, the D400 et-al are pretty amazing performers and my main gripe with them (other than general parts availability) is the “rubber” diaphragm cover, I bet @James79 could print out a two piece cover that would/could get a lot of these old beasts back in service.

 

[Open Ocean Diver]

Anyone who has D420 for sale I would be interested in buying.

 

[happy-diver]

Where has this thread been
Who does this
Unbelievable!

 

[rsingler]

Well, learned something new (duh!).

When expecting to struggle with pulling the case off a gnarly old D, I'd left the hose on while I took a preliminary look at the condition of the valve inside.

To my surprise, the stiff case came off easily, because the hose acted as a handle against which I could pull. My new plan? Always leave the hose on until the case is gone. I'll edit the post above.

 

[scrane]

More than one way to skin a cat.

 

[scrane]

I work on all my regulators except the D400. When it comes time for servicing my D400 off it goes to @rsingler for his special treatment. He has parts and is meticulous in his work. If you have an active D series regulator or one that has been gathering dust for years I would urge anyone to take advantage of his skills. The D300, D350, and D400 are still some of the easiest breathing regulators ever made.
Here's mine a few days ago!

 

[halocline]

I have several D300s and they are fantastic breathers. I don’t find them difficult to work on, unless you have to remove/replace the pre-dive spring, then it becomes an entirely different experience!

Once again, a great thread, just excellent work by Rob to share this detailed information.

 

[Redbeard04]

I recently bought and restored a mk20/D400 combo and have it cracking at .8 inches of water. I am looking forward to diving it but it came with a cracked rubber diaphragm cover. Does anyone have a spare in good shape they are willing to part with?