You mean this sort of calibration?
Good tip: the video above doesn't say anything about precision, but I like John Lee Hooker in the background. 🙂
But then again, I think a better LCR meter is indispensable, like the DE-5000 that sells for about $100 on eBay.
Using a jeweller's loupe held by hand (!) in front of the lens of a telephone to assess and fix a scuba regulator 1st stage (it converts the 300 bar of the cylinder down to 9-10 bar for the 2nd stage): the "Before" pic shows fine scratches that create pressure creeps, and, after a good polish, the "After" pic shows the item as good as, or better than, new. Only the edge at the top does the sealing, the stemp does nothing.
Attachments
Don't know, it was the first time I took this particular one apart; I have about a dozen of these (wife, 2 kids, yourstruly, and spares). It was freshly serviced by a shop in Singapore, and the pressure was creeping up, so I had to deal with it.
Intermediate pressure creep is relatively common in Scubapro piston 1st stages; there could be a few reasons why, the most plausible one is the service guys just dump everything together in an ultrasonic bath. I always give the piston its own private bath. Other causes could be careless handling, dirty water, salt crystals, and so on.
As long as you mark the unit in some way so if the problem comes back you will know something else is wrong.
I would like to continue to see your contributions.
I would like to continue to see your contributions.
Sounds frightening.
How many divers become in deep trouble because of a malfunction in their gear.
Hans
How many divers become in deep trouble because of a malfunction in their gear.
Hans
The topic really belongs to scubaboard.com: everything I know, I learned from there, and gave back some.
There's as much snake oil in servicing dive gears as in high end audio; so here's a few for your entertainment:
- "It's life support! Leave it to certified professionals! You'll die a horrible death if you mess with it yourself!". The proof is in a couple of posts above.
- "Dive gear must be serviced annually by professionals!". Scubapro, a leading manufacturer, once boasted about the "millions of cycles" for the special plastic seats used to seal the piston stem. Assuming a normal breathing pattern of about 100-200 per hour, and about 10-100 one hour dives per year, do the math: it's in the range of 100-1000 years!. I test my gear before each trip, and service them if something unusual comes up, or every 10 years, whichever comes first. 🙂
- "Parts for servicing are sold to professionals only." (we don't want no lawsuit). Luckily, this is a US-only policy. Parts are available off the shelves everywhere else in the world.
I assume you don't dive alone and know how to share air if deep enought to matter. To my mind the risk is running low on air while doing a controlled ascent from more than 18 M deep. But I suspect you don't go more than 60 M. Deepest I have gone was less than 100 M, but that was rescue work and a really stupid story. Statistically diving is safer than driving by some measures.
As to certified professionals, I can tell you a few scary stories. Knowing your gear and checking before every dive trip is of course the best and only way.
As to certified professionals, I can tell you a few scary stories. Knowing your gear and checking before every dive trip is of course the best and only way.
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It's all part of the mandatory training. When I was certified many moons ago, ascent from 20M with NO AIR was a required test; I think they dropped it because of the risk: if the student does not exhale continuously during the ascent, big trouble!
For recreational diving, accidents are rare: out of my 600+ dives, I have only a few incidents, most of them my fault, really, but nothing lethal.
For recreational diving, accidents are rare: out of my 600+ dives, I have only a few incidents, most of them my fault, really, but nothing lethal.
Obviously nothing lethal! 😉
Rule of thumb 10 almosts for 1 bad news.
On many items of pro rental gear there are identifying numbers so they keep track of the items history. Much nicer now that you can keep that information in a database. Beats the old filing cabinet full of folders containing carbon copies.
I hate to mention all the details about simple projects I didn't record because at the time I thought they were obvious.
Rule of thumb 10 almosts for 1 bad news.
On many items of pro rental gear there are identifying numbers so they keep track of the items history. Much nicer now that you can keep that information in a database. Beats the old filing cabinet full of folders containing carbon copies.
I hate to mention all the details about simple projects I didn't record because at the time I thought they were obvious.
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Lemme see, scale of 1 to 5, 5 is fatal:
- Lost in a cave, France: 4
- Strong narcosis during a 67M dive on air, France: 4
- Out of air during a deco (not safety) stop, Mexico: 3
- Bitten by a moray (not equipment related), Maldives: 3
- Near out of air during a deco stop, France: 2
- Near out of air during a deco stop, Mexico: 2
I use Excel to track, by serial number: pressures (intermediate & cracking) before & after, work done, parts used, number of dive since last service, date.
... Yes, like diving in a swimming pool.
For the real thing, vacuum state is the only true path to salvation. 🙂
Actually, in the 50's & 60's my family belonged to a "swim club." A large pool with 2 diving boards, a 6" deep kiddies' pool where the yellow water was changed every morning, a snack bar, tennis courts, volley ball court, ping pong tables, shuffle board courts and lots of tables with grills for dining.
As the club was located far enough outside the city, it drew the water from a well. That resulted in a unique aspect, it was salt water! For those who don't know the interesting difference, it is easier to float in salt water and it doesn't sting your eyes.
I liked to swim underwater and as I got older eventually I could swim two laps on one breath. I also learned Red Cross sponsored life saving.
Then there was a fellow who realized the advantage of teaching what was then called "skin diving." (Now considerd a no-no term for scuba diving!) Thus I got to learn the basics. Qualified by doing lake dives. Around here some folks do river dives. Current and recreational boaters who don't know what a diving marker means and the muck that can be stirred up by large boats tend to make this not a very popular choice.
Of course two of the rivers (out of the three) have locks and dams. I did know a pair of canoeists who got too close to a dam. One survived.
So don't knock learning the basics in a pool.
Otherwise we can discuss electrodynamic loudspeakers to go with your red hot power amplifiers.
As the club was located far enough outside the city, it drew the water from a well. That resulted in a unique aspect, it was salt water! For those who don't know the interesting difference, it is easier to float in salt water and it doesn't sting your eyes.
I liked to swim underwater and as I got older eventually I could swim two laps on one breath. I also learned Red Cross sponsored life saving.
Then there was a fellow who realized the advantage of teaching what was then called "skin diving." (Now considerd a no-no term for scuba diving!) Thus I got to learn the basics. Qualified by doing lake dives. Around here some folks do river dives. Current and recreational boaters who don't know what a diving marker means and the muck that can be stirred up by large boats tend to make this not a very popular choice.
Of course two of the rivers (out of the three) have locks and dams. I did know a pair of canoeists who got too close to a dam. One survived.
So don't knock learning the basics in a pool.
Otherwise we can discuss electrodynamic loudspeakers to go with your red hot power amplifiers.
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Talking about speakers, has any of you already come across a Sony television who’s screen has a double function as display and electrostatic spkr.
I found this very innovative, because electrodynamic speakers in flatscreens are of very poor quality to say the least.
Hans
I just ordered a Sony but not with panel speaker - that’s on the higher end models.
What I find interesting is that they can flex the OLED panel like this long term without it damaging the pixels.
What I find interesting is that they can flex the OLED panel like this long term without it damaging the pixels.
I am currently testing resistors for distortion again. One of the interesting bits is that leaving the full length leads on the Vishay resistors picks up enough EMI noise that they are at least 20 dB noisier than surface mount parts.
I do have a brass box I use to enclose the parts under test. To get the noise down I now use two .062" steel shields spaced 3" & 6" away from the brass box. That seems to get me another 30 dB of shielding. Getting close to looking 190 dB below the test signal.
As to TV sound one scoreboard manufacturer has done a scoreboard with enough pow area between the pixels they fire the loudspeakers through it.
I do have a brass box I use to enclose the parts under test. To get the noise down I now use two .062" steel shields spaced 3" & 6" away from the brass box. That seems to get me another 30 dB of shielding. Getting close to looking 190 dB below the test signal.
As to TV sound one scoreboard manufacturer has done a scoreboard with enough pow area between the pixels they fire the loudspeakers through it.
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That sony TV is using "actuators on the back. Its really a polyplanar speaker. And do you really want your TV shaking when the sound it loud? it does not help the sharpness.
You got me curious, so I did the calibration and some caps testing:
- 2uF (2.048uF & D=0.001 as per my 0.7% Megger LCR): 2.043u, 1.3R
- 100nF 1%: 100.6nF
- 10nF 1%: 9981/9937/9944pF
- 1nF 1%: 1001/995/996pF
I'm blown away!!!