HID Wierdy....

caveseeker7

If Stuarts post doesn't raise that concern, I rather doubt my opinion will.

Glad you find it amusing.

The standard is available for purchase afaik, I'll find out for you if you're intrested.

After the initial public posting of of the PRISM's test data SMI was asked not to publish any more of it.
Any non-classified data however is available for review in their office, and there is quite some of it.
I spend several hours pouring over it.

By the way, I don't think anyone has thanked Stuart so far for finding the problem, getting the fix and sharing it.
Thanks.

Now if you want to trade the HUD killing light sabre for the HUD friendly 8 D-cell in the back of my closet ...

__________________
Cheers
Stefan



"Political Correctness is a doctrine, fostered by a delusional, illogical minority,
and rabidly promoted by an unscrupulous mainstream media,
which holds forth the proposition that it is entirely possible to pick up a turd by the clean end.!"

schford

Chaps,

I just wanted to share this and see if any one else experienced a problem and if they did so they knew what the short term fix was.

For me it was a minor irratation that the HUD failed, the unit was still diveable and I did put about another 10 hours on it.

The reason you had to wait over 24 hours before swtiching both computers off and resetting is so the Shearwater does not loose your tissue loading and screw your deco up! Incidently to prevent it hold the ballast out to the side when you switch the torch on.

I think its great that the PRISM has been tested against this - but one of the things I love about the Meg, Bruce and Leon is if you tell them about a problem, then they work on the fix and within weeks release it!

For the record I don't think any unit is totally perfect and would not want to hide the fact I had an issue on my Meg, if I had wanted to I would have just spoken to Leon and Bruce on the quiet.

This is the only fault I have had though and I am sharing it with you all - I would worry far more about poor build quality or parts breaking or maybe being able to put a scrubber unit in upside down it is my belief that no unit is perfect and what is the correct unit for one person with their very subjective scoring evaluation criteria will be different for others.

To end on a positive note on one dive some numpty dropped a cylinder on my shearwater hand set and.....nothing happened.

Now I'm off diving for the weekend *waves*

Stuart

prismdiver

Funny you should say that about the nuclear device, the "test" PRISM was subjected to just about everything else. There is a fascinating photo of the PRISM bolted into a cage for a high intensity radiation test somewhere ( imagine a CCR in a S & M pose ! ). For anyone interested in exactly what it was put through can view the test at SMI's new shop in TN. They usually have the results at DEMA, etc... There are a few photo's on SMI's website, although they were "officially" requested NOT to post the final results on the internet, they are usually very happy to show the results as it's a VERY favorable report. A certain number of units were purchased for diver testing, fit and function, etc. However an extra unit was acquired for "torture" testing that was expected to be tested to destruction, however at the end of testing that unit was still fully functional. As you've pointed out, the majority of the testing was well beyond the ability of the poor diver that would potentially be connected the rig to survive. The goal was apparently to see within reason what would break the unit.

As I recall the testing performed included:
1. Frozen for 48 hours, thawed and verified operational
2. Heated to 100 - 125F ( I forget ) and verified operational
3. Volatile offgassing. To test for harmful chemicals leaching out into the atmosphere or into the diver.
4. Table shake test ( to see if bits fly off )
5. Radiation test. Informally a coast guard strobe was fired into the electronics, formally a high intensity radiation source was aimed at it, the test results tell the frequency and power. ( It was extremely high )
6. Source code for the electronics was reviewed line by line by the US Navy
7. The electronics were connected to a testing device and fed values determined by the Navy which simulated failed sensors, battery, etc... Thousands of hours were logged.
8. Breathing machine to test WOB
9. Canister duration
10. Setpoint control
11. Drop test

A lot more was tested, this is what comes to mind right away. If this testing were performed by a civilian agency it certainly would have cost in the multi-million dollar range - imagine a facility the size of NEDU focused for six months on testing a rebreather.

If you own a competitors CCR this probably sounds like PRISM divers crowing, maybe it is ! However if you are looking to purchase a new CCR this truly independent test information is rare simply due to the prohibitive cost. Imagine ( insert your favorite auto manufacture here ) telling you THEY crash tested their new car and it's great, VS. Car and driver buying one from the lot and independently testing it.

caveseeker7

As I said, Stuart, thank you for that.

I'd probably feel a bit queezy about that, but I'm glad to hear the Meg kept operating and you didn't have to can any dives.

Makes sense. The only way to prevent that is to have separate computers for setpoint control and decompression.

Stuart, unless the problem has already been solved with a change you don't really know that. All you know is that the Meg team is working on it, which certainly is highly commendable.

However, the way you worded this sounds like they are the only manufacturers doing so. That is certainly not the case.

Gordon and Kim at Jetsam always have an ear for their customers' feedback, their thoughs, concerns or problems. Continious changes and improvements to both Classic and Sport Kiss are proof of that. And they have earned an excellent reputation with their customers for it and the service they provide.

The same is the case with Pete and Shas at Steam Machines. I have witnessed them bending over backwards to acommodate their customers. They always listen to feedback, they help troubleshooting by phone and have continiously implemented improvements on the PRISM over the years. I have seen Pete help trouble shoot and Shas trying to source parts for old MK15s, a CCR they never sold, belonging to people they didn't know.
They too have earned the trust of their customers.

If the build quality is referring to the PRISM, it's pretty damn good as long as you take reasonable care of it.
Good build quality is one thing, good engineering another. The PRISM has both.

By the way, have you tried to insert the absorbant cannister upside down yet?
Try it sometime, I'm curious.

To quite some extend I agree with that. Many of the features and layout of a rebreather are personal preference ... location of counterlungs, manual or electronic setpoint control, size, weight and scrubber duration, features auch as gas management, flood recoverability and integrated deco, and much more as I see it.

But I strongly believe there is a also a need for objective scoring, for independent testing. Some basic safety related issues should be implemented, and anything on your rebreather needs to work safely and reliably. From the basics, such as source code, displays, scrubber and the setpoint control to additional features like QC, gas management, valves, deco computers, they all have to work.

That's beyond a personal score card and the reasoning behind CE certification or military testing.

__________________
Cheers
Stefan



"Political Correctness is a doctrine, fostered by a delusional, illogical minority,
and rabidly promoted by an unscrupulous mainstream media,
which holds forth the proposition that it is entirely possible to pick up a turd by the clean end.!"

bgpartri

I've done some more testing, and I still can't simulate the problem. I have tried two different heads and several HID lights. I have stacked lights on the head including dual 24 watt video lights.

So at this point I don't know what we're dealing with. It could be radio frequency, electro mechanical, or magnetic. But I can say with some comfort that it is not a normal output from an HID light.

If it happens again, there is no need to reset the primary controller. It is unaffected by the pulse.

All that happens to the HUD is that is recalibrates unsuccessfully.

I have been told that RFI does not propagate through water, if this is RFI, so it is unlikey to be a problem in real diving conditions.

I will continue to build electronics that might be destroyed by a nuclear blast but can survive being dropped.

Bruce Partridge

jv2000

Without wishing to be in any way offensive - you PRISM guys come across as being very defensive -its a nice bit of kit I admit it but schford didn't say that poor build quality was referring to the PRISM if I laid money on it I bet he was referring to inspirations (oops bet I jus tinsulted mose of the site now!)! Although you have led me to wonder about it - I think the only people to get some PRISM latelies have been our Ozzy guys - you guys had many problems? IF so please share em like schford has with his MEG - its how we all learn.

And why do you guys keep blowing on about Navy testing - didn't it fail the tests and didn't they choose not to buy any PRISMs? Hey I might be wrong here if so just tell me they have definitivly bought some as a buddy of mine who is in the Navy said they were not going to buy any.

Peace all and remember everyone is entitled to their opinions!

John

__________________
***********
Dive Dreamer

jitka

Hello Stuart and all,

I just had a similar experience last week with my Meg (Apeks) HUD failing temporarily on a cave dive to 80m. It went off and stayed off for about 15-20 minutes and than it turned back on during deco.
I used HID 10W Czech made DTD light (by the way very excellent light).
I dive the same light all the time and it happened only the one time so far.

I was away from email since so I didn't have a chance to contact Leon or Mark Meadows and ask what they think about it.

But a friend of mine and long time very experienced CIS Lunar diver confirmed similar experience with the CIS handsets enterfering with powerfull video lights (400W)...


Hope we figure this out soon.


Jitka

ROB DAVIE

Originally posted by Bruce Partridge: The Meg main unit signals the HUD across a wire when it wants it to turn on or off, or to calibrate. The signal is precisely timed, and the HUD will ignore any signal that doesn't go on and off in the right times. For example, to cause a calibration, the signal must go on and off in 100 uS, then go on again in 200 uS. There is no communication from the HUD to the main computer.

I put the timing in so that turning off the main computer or having the battery fail wouldn't turn off the HUD. And it doesn't. However, I didn't plan for active jamming.

The HUD is receiving the calibrate signal, and can't calibrate successfully, so it displays the calibration failure signal.

I've tested my Meg with both a DiveRite and a Sartec HID and can't duplicate the problem, so I suspect that the light in question radiates a lot of interference. That could be because of the design, or maybe just because of the power. I'll dig out my dual 24 watt Halcyon video lights, charge them up, and give that a try.

An RFI shield in the form of a copper or aluminum piece of metal, or one of the sprays or paints available should fix it. But I have no way of testing it because I can't duplicate it.

BTW, the communication from the controller to the handset display is plain old low speed serial.

Bruce Partridge
Shearwater Research Inc.--End quote.


Folks,

Bruce has said some very important things here that bear directly on this unusual situation.

As he puts it:
"I put the timing in so that turning off the main computer or having the battery fail wouldn't turn off the HUD. And it doesn't. However, I didn't plan for active jamming. "

I would have to say in his defense that it would not be expected ordinarily, since he was not building a military system!

This kind of odd and un-planned for occurrence is not unknown in the aviation industry. A terrible "for instance" is TWA Flight 800. The industry used the absolute best wiring insulation known at the time when they built the beast. Tanks with built in pumps were tested to failure without catastrophic occurrences. We, myself included, flew the 747 across the pond with just a bit of fuel sloshing around in the center tank thousands of times.

Then, in one case, with one particular combination of age of the wiring, total tank temperature, pumps running (standard procedure), and fuel vapors, we have DISASTER!

With all of the planning, good engineering practice, and testing, that one unforeseen combination of factors caused a catastrophe. Sometimes the absolute best that we can do as human beings is just not enough to prevent all possibilities from happening!

I am sure, now that Stuart has so cleverly discovered this problem, Bruce will engineer the "fix" to protect against this situation in future!

As for the Navy, and its testing of the Prism, (...a subject which was included as a comment on testing theory and protocol...), I would first have to point out that the Navy testing protocols are uniquely the U.S. Navy's. Other agencies (such as the CE group), other military units, and certainly every other manufacturer use differing methodologies; sometimes widely so.

As for the Navy's testing of the Prism units offered by Steam Machines, I will simply point out that the units PASSED the Navy's tests. The unit was not SELECTED for Navy use, for reasons that are not specified publicly by the Navy. This could be anything from the fact that it is not NON-magnetic enough (It was not designed as a mine clearance unit.), to the fact that other units would not agree to use it (for whatever reasons) and thus caused a rejection for reasons of equipment commonality, or simply that some uniformed bureaucrat wanted another unit.

(For puposes of complete disclosure, I do not own, nor do I dive the Prism. I do know Shas Readey personally, and Peter by telephonic contact. I have found them both to be very plesant, and very willing to supply information whenever possible.)

Since the Navy chose not to make its reasons public, which is normal, all else is purely and simply very idle speculation.

I would like to thank Stuart for bringing up this unusual occurrence, and Bruce for getting right on top of the issue. It is this kind of event that makes this Board so extremely useful!

Rob

__________________
"CC Rebreathers will become a viable part of tech diving WHEN PIGS FLY!!"--GI3

UWSojourner

Quote:
Originally Posted by UWSojourner
Maybe not, but you clearly attempted to raise concern about its appropriateness as a life support system .


Wow, you're diving pretty deep in BS. Time to come up.

schford

Folks,

I am gonna steer this back on topic here please could we keep it there then....

Update - I tried to cause the HUD to fail underwater by turning the unit on with the ballast right next to both the HID and the Can - no joy, so it would appear that Water does indeed block the RF interference or what ever causes it.

Stuart