Servicing a Calypso Depth Gauge

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Discussion of diving methods and equipment available prior to the development of BCDs beyond the horse collar. This forum is dedicated to the pre-1970 diving.
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SurfLung
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Servicing a Calypso Depth Gauge

Tue Oct 10, 2017 10:14 am

Servicing the Calypso Depth Gauge...
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- It's tough to get a Calypso depth gauge in good shape. I've been messing with one after another for a couple of years and I think I've learned how to restore/service them. I have three and have cobbled together two out of the three that are working well. The one with the best lens had the internals of the bourdon tube completely clogged with corrosion. My best one was a newer version with orange face and black plastic case... Identical to the chrome ones except for a larger pressure port screw. This one was brand new in the original box... Had never been wet. It leaked completely the first time I dove it. So, I would recommend servicing even to ones that appear in the best condition. Here are a few tips:
1. These are supposed to be just air inside... Don't fill them with oil.
2. Don't try to pry the lens off. It is held in by suction and will chip and then crack across the face. The lens is VERY fragile.
3. Make/grind a proper spanner head screw driver so you can unscrew/screw the pressure port without damaging it.
4. There is a weird O-Ring arrangement that needs to be replaced for reliable seal. It's weird because it seals the gauge to the case to the pressure port... three surfaces. I don't remember the O-ring but I found exact replacements at my local Ace Hardware.
5. If the lens is fine, I recommend not trying to take it off. If you want to swap in a better (not cracked) lens from another Calypso, then the best way to remove the lens is by inserting a jewelers screw driver into the pressure port (with the screw out) and pushing the whole internal mechanism up against the inside of the lens. It will pop out and reveal a very thin O-Ring seal around its circumference.
6. Re-Assembly Procedure: Install the lens first. If you don't you will not be able to fully insert it against the air pressure inside when the pressure port is sealed. So, Lens first. Then pressure port with new O-ring. I recommend silicon grease on the O-ring so that it will settle into the three surfaces it has to seal.
7. The quality of the spanner screw driver you made is important. The pressure port not only seals everything against the O-ring, it also secures the mechanism in the case. So you need to get a good purchase on that pressure port and screw it all the way in tight.

Saving a Flooded Calypso - Drying out the inside is nearly impossible without removing the lens. But I don't recommend removing the lens unless absolutely necessary. I was able to dry out the insides of my flooded gauge without removing the lens, here's how:
1. Unscrew and remove the pressure port.
2. Empty out the loose water.
3. Fill the case about 1/4 full of rum. Shake it around to mix with any water residue. Empty out the rum and repeat.
4. Now, to evaporate the rum residue, place the gauge on your dashboard in the sun with the pressure port facing up so that the rum vapors can escape. Just let it sit in the sun like that and the heat will dry it out completely.
SurfLung
The Freedom and Simplicity of Vintage Equipment and
Vintage Diving Technique are Why I Got Back Into Diving.

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Bronze06
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Re: Servicing a Calypso Depth Gauge

Tue Oct 10, 2017 1:12 pm

Thanks for the write up.
"Where'd ya get that ol' thang, don't cha' know them thare things ill kill ya!"

Live From the Red Sea,

Russ

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Bryan
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Re: Servicing a Calypso Depth Gauge

Tue Oct 10, 2017 2:04 pm

A+ Thanks for doing that
Doing it right should include some common sense, not just blindly following specs and instructions. .Gary D, AWAP on SB

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tripplec
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Re: Servicing a Calypso Depth Gauge

Tue Oct 10, 2017 9:04 pm

Mine shows 30 feet at 25, 60 feet at 50. The preasure port is prety badly corroded. Is it worth trying to take apart and clean, or should I just use it as a novelty item and pretend its accurate? Mine is also the 100 foot dial.

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antique diver
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Re: Servicing a Calypso Depth Gauge

Tue Oct 10, 2017 11:10 pm

I hate to take apart one that isn't leaking. I used to put Calypso's with corroded inlets into a cup of vinegar and put it in my test chamber to 100' pressures to force the vinegar in. Let it soak until working, then do fresh water rinses in the chamber to rinse all the acid out.

If you can access a chamber at a real dive shop that likes to help people this might help your gauge. The advantage of taking it apart is you can pull the needle off and try to reset it until you have accuracy improved, but may take a lot of disassembly/reassembly, and trial and error in and out of the chamber.

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tripplec
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Re: Servicing a Calypso Depth Gauge

Wed Oct 11, 2017 1:02 am

I wont be taking the lens off. So I'll probably just leave it alone. No one will know it's off a phew feet.

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SurfLung
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Re: Servicing a Calypso Depth Gauge

Wed Oct 11, 2017 2:10 pm

- So I suppose to calibrate one of these, you'd have to have the mechanism in the open air at sea level pressure and have a sealed pressurization hose connected to the pressure port.

The new-in-box orange Calypso gauge that I flooded and dried out has a perfect lens and a movable "No Deco Limits" bezel. Could be very handy as a backup to my Diving computer. It's pressure port screw sticks out and unscrews with a pliers. This port was loose when I opened up the gauge to drain out the water. So, either the O-Ring had shrunk or it wasn't tight enough to begin with. From this I learned to check the O-ring seal before diving with ANY Calypso depth gauge regardless of its visual condition.

BTW - All of the stuff I said NOT to do is stuff that I did and wrecked or damaged a gauge by doing it... Filled one with mineral oil, pried on a suction sealed lens until it chipped and flowed cracks across its surface,... I am suspecting that most of the lenses on these Calypso gauges are embrittled by age. VERY easy to nick or chip and the chip almost certainly develops into a crack.
SurfLung
The Freedom and Simplicity of Vintage Equipment and
Vintage Diving Technique are Why I Got Back Into Diving.

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antique diver
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Re: Servicing a Calypso Depth Gauge

Wed Oct 11, 2017 10:32 pm

SurfLung wrote:- So I suppose to calibrate one of these, you'd have to have the mechanism in the open air at sea level pressure and have a sealed pressurization hose connected to the pressure port.



Yes, you have to make up an adapter to do this. An extra brass inlet piece can be soldered to an appropriate fitting to adapt to a hose. Or a machinist can make one with a small lathe. A good adjustable low pressure source set to a known depth equivalent pressure is applied to the gauge with the lens off. About mid-range on your depth gauge is a good starting place. Did you see the post I made of the gauge needle puller? use something like that to pull the needle from the stem and replace it at the depth corresponding to the pressure you are applying. Tap it gently back in place and put the whole thing back together. Repeat as needed until satisfied. Yes, it is a lot of trouble... that's why I "used to" do it. :lol:

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SurfLung
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Re: Servicing a Calypso Depth Gauge

Tue Oct 17, 2017 9:56 am

Pool Tested... It Works!
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- I took the two serviced/repaired Calypso depth gauges to the pool on Sunday. Rich and I did some Scuba diving. My ZOOP computer registered 11 feet deep resting on the bottom of the deep end. BOTH of my Calypso depth gauges registered ZERO depth. What the...?
- They both sealed out leaks perfectly but neither was reading the depth. I was trying to figure if I somehow got the O-Ring too tightly squeezed... Maybe it was blocking the inlet port? When I got home, I took the inlet port off of the NOS Orange and black one (Aquarius). It all looked fine. But when I pushed a paperclip thru the inside of the inlet port, it seemed to run into a flexible membrane. You can see the 4-hole exterior of this inlet port. Maybe the membrane was supposed to transfer the pressure without letting any water in?
- Whatever it was supposed to do, it wasn't letting the water into the bourdon tube. So, I punched the paper clip thru the membrane several times until I could blow thru the port freely. Then I re-installed it just like before.
- At the pool again this morning, swimming laps, I brought the Aquarius depth gauge and did 3 free dives to the 11 foot bottom. The gauge read 11 feet deep perfectly! I like this gauge. I can set the bezel to match the no Deco time from my ZOOP dive planner and have a backup.
- Tonight I will clean out the inlet port on the chrome Calypso gauge and then test it again at the pool when I swim laps on Thursday.
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Calypso vs. Aquarius - The newer gauge is called "Aquarius" but it is mechanically identical to the Calypso on the inside. The lens is the same. And the housing/body is the same except for being made out of plastic. The No Deco bezel can be snapped on and off and can rotate to set it according to your dive plan. The only difference otherwise is the inlet port... Calypso's inlet is flush with the case and a directly open hole into the bourdon tube. The Aquarius inlet sticks out and has that internal membrane I mentioned above.
SurfLung
The Freedom and Simplicity of Vintage Equipment and
Vintage Diving Technique are Why I Got Back Into Diving.

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