calibration problems

i have popped in a new battery , no change , the cells are fine according to the computer and the hud reads them as good also otherwise it wouldnt pass calibration , this is my understanding ?
i dont think its the cells here otherwise theyd all have to fail at the same time ?
cheers
silkyshark
 
From your description, cells are extremely unlikely to be the source of the fault.

However: it's a LOT easier to switch a cell and see how it cals/reads than it is to pop the HUD in a post pack, send it to SWR, wait three weeks, get it back with an invoice listing "No fault found: check cells".

So eliminate the dumb stuff just in case, then ship it off.
 
silkyshark said:
hi all , any ideas as to why , when i calibrate in o2 that the shearwater reads .98 which is normal , but the shearwater hud once calibrated in the same gas content, blinks two reds?
cheers
gordy,,
Click to expand...

Use the dreams, the problem wont happen.

I love shearwater the products are first class but you dont ever want to put al of your eggs in one basket.

The Revo Dreams were great the new Dream P is the best passive monitor made today.

Switch up the electronics.
 
Hi
Just an idea ...

Does the shearwater consider you are at the sea level? or did you validate the compensation of the atmospheric pressure?

If you are at an altitude higher than sea level, that may explain the difference between Shearwater and Hud. The shearwater consider you have 0.98 because the SH assume you have a 1013 mbar atmospheric pressure but maybe in reality you have 0.91 ppO2 because the real atmospheric pressure is 930mbar (for instance).

My suggestion: try to put the SH in automatic atmospheric pressure compensation mode and see if it has a positive effect.

It's just a guess as i don't have the HUD from shearwater

My 2 cents ...

Philippe
 
silkyshark said:
i have popped in a new battery , no change , the cells are fine according to the computer and the hud reads them as good also otherwise it wouldnt pass calibration , this is my understanding ?
i dont think its the cells here otherwise theyd all have to fail at the same time ?
cheers
silkyshark
Click to expand...

Are you calibrating the two units at or near sea level? If not, what is your altitude? Also, on the predator, do you have the altitude adjustment set for sea level or auto? If you have it set to sea level, set it to auto, re-start the predator and see what the PO2 reads after a flush. If it still reads .98 (I am assuming you have your cal. gas set to the default of .98) then something is definitely amiss.
Lastly, what are the mV outputs of the cells in air and O2? Are the outputs at those two O2 concentrations linear? (Air mV X 4.76 should equal the mV output in 100% O2).
 
MatthewA said:
Are you calibrating the two units at or near sea level? If not, what is your altitude? Also, on the predator, do you have the altitude adjustment set for sea level or auto? If you have it set to sea level, set it to auto, re-start the predator and see what the PO2 reads after a flush. If it still reads .98 (I am assuming you have your cal. gas set to the default of .98) then something is definitely amiss.
Lastly, what are the mV outputs of the cells in air and O2? Are the outputs at those two O2 concentrations linear? (Air mV X 4.76 should equal the mV output in 100% O2).
Click to expand...
As Captain Starfish pointed out it with the splitter, this is irrelevant here. It's important in as much as the calibration could be inaccurate, but the HUD wouldn't know or care that it was inaccurate.
You show it a gas - you press "calibrate" to say "this is 1 bar O2" and it should indicate that same gas as 1 bar O2 (regardless of what it might be in reality - up to a point).
 
hi all , its a working system for a number of yrs , i calibrate at sea level if thats any good , if i get time later on tomorrow i will recheck all the wiring as far as i can and let you know how i get on , its more than likely something very minor and i know that the guys from narked@90 will be able to fix it in a jiffy if it needs to be sent in for repair , i just cant get my head around any thing that im not thinking about so to speak ,,, and ive never heard of this happen to anyone before ??
silkyshark
 
Nah, it's a weird one - good luck with the hunt and please do let us know what silly thing it turns out to be. It'd be good to know.

I have an older SW HUD on my inspo, really appreciate it even if for some reason the middle channel has carked it and refuses to calibrate or recognise a cell. The other two work well, it's a very simple and well behaved unit, and it saves a lot of fumbling with handsets :)
 
well it looks like i might have corrosion on the wiring inside the loop , otherwise known as blackrot , will be sending the hud and predator down the narked @90 for them to take a look an see whats ,what , i can find nothing else wrong with the setup as is ,
cheers for the input and i will let u know how it pans out ,
silkyshark,,
 
ok all , its been awhile and just a wee update , the entire wiring system was badly damaged with blackrot and the hud had also damage inside the board , have had too completely renew the hud system ie new electronics and wiring , the computer is fine , but the wiring from the cells to the pod and to the computer has been replaced , so basically a complete rewire and new hud have now been fitted ,
thanks guys for your input ,advice and im now happy with the outcome ,
it seems that blackrot in the loop is a problem common to quite a few rebreathers , and it does have an adverse effect on the electronics !!
if you discover that your wiring has blackrot then get it replaced as a matter of the most importance !!
HTH
silkyshark
 
How do you detect black rot. Can you see it on the wire casing or is residing on/ in the wire itself?
 
black rot seems to effect the wiring in the loop , if its exposed to the wet , high po2 , we , were unlucky in the aspect that yes the wiring in the loop had been badly effected by black rot and needed replaced , but also the hud system had been affected as well , this might have been caused by a slight nick in the cable sleeve that we spotted , but how it got to the hud electronics and corrupted it is beyond me , the guys at narked and also at revo did a fantastic job of getting the
problem fixed , and i was told that it wasnt a unique, in that the guys at narked had come upon this quite a few times in the past , if it is a problem that , lets say can occur then people should be at least made aware of it , as it has the potential to adversely effect the electronics that are controlling a life support system ,
if you can lnspect any parts of exposed wiring that is in the loop , as once black rot gets in , it seems to track up inside the sleeving , starting at the cells and work back , in our case even though there was plenty of excess wiring , the rot had travelled right along the entire length , so we couldnt cut away the affected bit , so all was replaced ,
on the plus side , although the unit is five yrs old and has done quite a lot of diving , it now has basically a brand new electronics package , the hud system has been completely renewed and the computer has had a new screen and new wiring put in all the way to the cells , all that remains is someone to go diving on it !!
HTH
silkyshark
 
What in the heck are you getting in the loop that will rot out the wiring like that. I find it hard to believe that it would happen just by normal usage.

Have you ever heard of Listerene? :lol:
 
You must log in or register to reply here.
Back
Top