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Discussion Starter · #1 · (Edited)
went and had a check of my kit ready for a dive on monday and when i turned on my 1st stage (mk20 scubapro) to check them the high pitched whistle was unbearable every dog in a 5 mile radius must have gone bonkers. seems like its coming internally all hp lp o rings are fine.

whats happened to my kit :frown:
 

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Creature of the night
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A job for you local tech as it is probably the internal rubber diaphragm either unseated or damaged.

Safe diving,
Steve
 

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Creature of the night
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is that mega bucks steve??
The diaphragm's are only a few quid then there is the labour, depending on the make it shouldn't be too much. Certainly cheaper than a new one, I would suggest taking it in for a service as they have always replaced them when I have had mine [Apeks] done.

Safe diving,
Steve
 

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mk 20 noise

This happened to me after a week diving in Egypt using a 15l that had (as I found out to my cost) rust inside it.

The mk 20 does not have a diaphragm - it is a piston 1st stage. The 1st stage needs a service which will result in a service kit being fitted.

The noise is probably the result of a damaged / marked HP seat which would be replaced during the service.
 

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Discussion Starter · #6 ·
This happened to me after a week diving in Egypt using a 15l that had (as I found out to my cost) rust inside it.

The mk 20 does not have a diaphragm - it is a piston 1st stage. The 1st stage needs a service which will result in a service kit being fitted.

The noise is probably the result of a damaged / marked HP seat which would be replaced during the service.
yeah had a little strip down and it is a piston. will be taking it in for service. can you remember what kind of cost you incurred when it happened to you for the replacement parts??
 

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I went DIR... but my bungies pulled me back!
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I had a very similar thing happen to my MK25 1st stage, when opened the problem was located to the O ring which allows the turret to swivel. There is a post which passed down through the body of the first stage and stops above the HP seat, this post is hollow to allow the air up to the ports but around the outside there is an O ring, this should be replaced during a standard service so if that is the same problem as yours then it should not cost to much to replace.

Lets hope thats all it is.

Cheers

Darren
 

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mk20 noise

I do all my own servicing so am unable to give you a cost - service kits are around £10-£15 depending on the 1st stage which for a MK20 includes all parts such as O rings seats etc.

Getting the mk20 serviced should sort the problem out.
 

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The repair would be sorted by getting the reg serviced. The o-ring that is letting hp air get passed into the ambient chamber is replaced under service and is a specific o-ring needs to be used as it is under quite a strain as can have up to 300 bar on one side.
Holding the o-ring are two plastic rings these also need to fitted correctly, as you only get the whistle back.
 

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Be very careful when stripping the reg down the piston edge that closes on the seat needs to be protected. If you damage the edge you will get interstage pressure creep and will need to replace the piston and seat.
 

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Radioactive Diver
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This happens when you have insufficient lube on the piston o-ring.
If you wanted a cheap fix, apply plenty of lube to the piston parts, reassemble and check the IP. This should be constant, and is adjusted by adding or subtracting plastic washers to the spring seat.
 

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Lubricating can be a temporary fix. What can have happened is the o-ring being deformed due to the difference in the pressures in the reg. The o-ring can then be damaged necessitating replacement. If either of the rings to either side of the o-ring or the o-ring is of the wrong hardness (shure hardness of o-ring material) then it'll whistle dixie for you again.
Give the reg to some one who knows what is needed and has access to the correct parts.
 
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