How to restore a Scubapro Mark VII Honker

[rsingler]

Attached is an outline listing all the steps discussed in the previous nine posts.
It is in an editable Microsoft Word format for your corrections and additions.

Also, a couple of additions have been made to the O-ring Crosswalk upthread. A new version has been loaded.

I look forward to hearing from our senior members with their own Mark VII experiences, service tips and reminiscences. Please let me know of any mistakes that you find!

I am told that one of our very own ScubaBoard members might be the original designer of the Mark VII. It would be wonderful if we could coax some comments and corrections from him.

 

[Couv]

Another wonderful tutorial by @rsingler -thank you very much. I've only rebuilt two of these gems and I was fortunate that both worked as advertised upon completion. Well, after I hooked up the second stage to the correct port anyway.

I am told that one of our very own ScubaBoard members might be the original designer of the Mark VII. It would be wonderful if we could coax some comments and corrections from him.

You are correct!
The MK VII was invented/designed by Tony Christianson (@rtonyc ) who also invented/designed the ScubaPro Pilot and the Sea Pro Zepher.

http://vintagescuba.proboards.com/thread/4963/scubapro-pilot-regulator-came

FS or FT a SeaPro Zepher 2nd Stage regulator

 

[Perryed]

Thanks rsingler! I think my problem is the oscillator o-ring. It way to tight. Now I jut have to bite the bullet and buy 50-100 of them! I think I`ll try the other methods first and see how that works. Glad to have the options.

 

[jgttrey]

I'm confident I will never work on one of these, but this is really interesting stuff and, for me, the best part of SB. Great work.

Thanks @rsingler

 

[Perryed]

OK. I couldn`t stand it anymore so I rigged a set up that allowed me to pressurize the reg to around 120 lbs. I have an old J-valve and hooked my compressor to that and fed it in from the tube on the bottom as per my pic. Then I used my handpiece from my dental lab business (retired) and used a grooved rubber wheel to hold the original o-ring that had been replaced with a stiffer one from the VDH store. After a bit of sanding to where it would slide in and out much more easily I reinstalled it and hooked everything up. I found that the reserve feature worked on the J valve (no flow until I kicked it to reserve) and when I hooked up the 109 and breathed, low and behold she honked! I still have to see at what pressure it starts but this is very cool. At least I now know the lower end that it will sound off.

Thanks rsingler!

 

[rsingler]

Mad Scientist!
I knew there was a reason I steered clear of dentists, lol!

But that Mk 7/109 shore is purty!
Or if you've converted it to a Balanced Adjustable, then no problem breathing at a tank pressure of 120 psi, lol! (Careful you don't get "vaper's lung" from the oil in that compressor's output.)

 

[rsingler]

As @Perryed has just demonstrated, if you haven't got access to a fancy o-ring replacement, and your oscillator o-ring 2-117 fits too tight...

sanding it down a little at a time is a legitimate, if unorthodox, way to get things to honk. Since this oring is not an air seal, a less than perfect outer edge is a non-issue (unless you sand off too much).
Here is an early experiment with the o-ring stretched around the outer perimeter of the oscillator, being gently sanded against a full sheet of Micromesh. It works, even if it's a little less elegant as a solution.

 

[Perryed]

The air is run through a very good filter and drying system as it was used with a sandblaster. 60 micron sand and moisture do not get along very well together! LOL! The 109 has a duro poppet but isn`t balanced though. At least not yet. I have to source a balance chamber for it. I also use the compressor set up to adjust the cracking pressure of the regs I play with. It comes pretty close to the IP. On the low side at 120 though.

 

[rsingler]

Courtesy of @Bryan@Vintage Double Hose , I downloaded a copy of the original owner's manual that was under the 10MB attachment restriction for ScubaBoard.
It's now attached to Post #3.

 

[Couv]

I've never considered sanding the outside of an o-ring; but it's not unheard of-and sometimes encouraged to sand the inside of a seal to remove the "flash." Flash is the tiny bit of material left over from the manufacturing process. Removing it is sometimes necessary especially on cheaper o-rings. Don't tell anyone-as some might think I'm obsessed, but I always ensure the flash is removed from piston stem o-rings. @Perryed I have a variety of -117 seals I'll be happy to send you-PM me your snail mail address and I'll get them out to you.