25mV readings?

OceanOpportunity · 19th February 2008, 13:40

hmmm...just bought new cells for a newly wired shearwater into my system. cells read about 13mV on a voltimeter, but read 25mV on the shearwater. Did I wire something wrong?

Stephane · 19th February 2008, 13:45

Hello,

Looks like you have two cells in series.

OceanOpportunity · 19th February 2008, 18:12

something must be in series...

ok, starting to lose my marbles. I have clearly identified which 3 wires are for which cell reading on the shearwater. Problem is running the grounds. Any suggestions out there before this thing ends up thrown through the window?

Stephane · 19th February 2008, 18:26

Quote:

Any suggestions out there before this thing ends up thrown through the window?

Yes, here is my address, I will take care of your Shearwater

Why don't you ask the wiring diagram to Bruce?
There might be only one wire for the ground.

Divein · 19th February 2008, 18:43

Off the FAQs

Shearwater products use wire that is white or white with a brown stripe for ground (negative). They will have three white wires that are interchangeable and three colored wires for positive.

Keep the board informed as to how you get on - I have to do mine yet and I am piggy backing them into a rEvodream as well so i have the HUD!

OceanOpportunity · 20th February 2008, 15:30

Problem solved. I can't honestly say what the specific issue was, other than that I tried several apparently wrong combinations of wiring. Generally speaking, I found it somewhat strange that there are not very clear instructions on how to wire the cable up. You don't have to be an electrician to figure it out, but considering that most folks have a VERY limited knowledge of electical circuits, a more detailed set of instruction would be helpful. Perhaps I'll work something up.

Anyway, short story is this...

In peeling back the outer cable sheath, you will find a copper wire wrap for strength down the cable, six colored wires, and an internal strength member. Some trial and error with one cell will lead you to quickly identify which wire is for which cell. Mark them. Now this leaves three unused wires. As it happens, the three cells share a common ground. Once the ground is identified, all 3 grounds tie in here. Clean it all up with some shrink tubing, and you're good to go. Double check mV's on the computer to read 10-13mV. Also double check that the cells are properly identified as 1-3 by unplugging one at a time. I permanently ID my cells and corresponding Molex connector by melting small holes in each with a soldering iron. Ex. 1 hole in molex and 1 hole in teh top of sensor 1, to denote sensor 1, and so on.

good excersize, and now on to diving!

Quote: (Originally Posted by Divein)

Off the FAQs

Shearwater products use wire that is white or white with a brown stripe for ground (negative). They will have three white wires that are interchangeable and three colored wires for positive.

Keep the board informed as to how you get on - I have to do mine yet and I am piggy backing them into a rEvodream as well so i have the HUD!

**SeaBass** · 20th February 2008, 16:07

Hi Mike,

Any pictures?

.

Quote: (Originally Posted by OceanOpportunity)

In peeling back the outer cable sheath, you will find a copper wire wrap for strength down the cable, six colored wires, and an internal strength member. Some trial and error with one cell will lead you to quickly identify which wire is for which cell. Mark them. Now this leaves three unused wires. As it happens, the three cells share a common ground. Once the ground is identified, all 3 grounds tie in here. Clean it all up with some shrink tubing, and you're good to go. Double check mV's on the computer to read 10-13mV. Also double check that the cells are properly identified as 1-3 by unplugging one at a time. I permanently ID my cells and corresponding Molex connector by melting small holes in each with a soldering iron. Ex. 1 hole in molex and 1 hole in teh top of sensor 1, to denote sensor 1, and so on.

Divein · 20th February 2008, 17:14

Pictures would be good as I don't do too well with words!!!

Are you saying that pin 1 (12 o'clock position under red dot) is the ground and all 3 white/brown cables link to it?

Thanks

kiwi_diver · 20th February 2008, 17:52

Due to conflicting info on the Narked@90 and Shearwater sites, I decided to take my fischer plug apart and find the numbers on the back of the plug.

The centre pin is pin 1 and you must wire all three sensor -ve to this pin. The sensor +ve go to pins 2,3 and 4 consecutively.

When looking at the end of the plug, with the pins sticking out at you, have the half shell on your left. The pin at 12 o'clock is pin 2, next clockwise is 3, and the next is 4.

You should meter the pins out to your cable ends as the colours may differ between cables. this can be done with a small test lamp or continuity tester.

My cable had no connections to the other Fischer pins, 5, 6, and 7.

Since posting this, I've found that Martin from TecMe had posted this good picture on another thread:

Divein · 20th February 2008, 18:12

That's really helpful. Thanks very much - time to get the soldering iron out this week-end!

19th February 2008, 13:40	#1 (permalink)
OceanOpportunity for a world of water Current Rebreather/s: Other CCR Dolphin Home Build Other Rebreather/s: Not Bought Yet Inspiration Classic Other CCR Dolphin Home Build Join Date: Nov 2006 Location: Providence, RI USA Posts: 544	25mV readings? hmmm...just bought new cells for a newly wired shearwater into my system. cells read about 13mV on a voltimeter, but read 25mV on the shearwater. Did I wire something wrong? __________________ Michael Lombardi Oceans of Opportunity www.oceanopportunity.com Elected Director, Society for Human Performance in Extreme Environments MN'07, The Explorers Club Project Manager, Diving a Dream
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19th February 2008, 13:45	#2 (permalink)
Stephane Stéphane Acounis Current Rebreather/s: rEvo Other Rebreather/s: rEvo Join Date: Nov 2005 Location: Nantes - France Posts: 769	Re: 25mV readings? Hello, Looks like you have two cells in series. __________________ Stéphane
(Online)

19th February 2008, 18:12	#3 (permalink)
OceanOpportunity for a world of water Current Rebreather/s: Other CCR Dolphin Home Build Other Rebreather/s: Not Bought Yet Inspiration Classic Other CCR Dolphin Home Build Join Date: Nov 2006 Location: Providence, RI USA Posts: 544	Re: 25mV readings? something must be in series... ok, starting to lose my marbles. I have clearly identified which 3 wires are for which cell reading on the shearwater. Problem is running the grounds. Any suggestions out there before this thing ends up thrown through the window? __________________ Michael Lombardi Oceans of Opportunity www.oceanopportunity.com Elected Director, Society for Human Performance in Extreme Environments MN'07, The Explorers Club Project Manager, Diving a Dream
(Offline)

19th February 2008, 18:26	#4 (permalink)
Stephane Stéphane Acounis Current Rebreather/s: rEvo Other Rebreather/s: rEvo Join Date: Nov 2005 Location: Nantes - France Posts: 769	Re: 25mV readings? Quote: Any suggestions out there before this thing ends up thrown through the window? Yes, here is my address, I will take care of your Shearwater Why don't you ask the wiring diagram to Bruce? There might be only one wire for the ground. __________________ Stéphane
(Online)

19th February 2008, 18:43	#5 (permalink)
Divein Custom Title Allowed! Current Rebreather/s: Dolphin Home Build Other Rebreather/s: Dolphin Home Build Join Date: Jun 2006 Location: Yorkshire Posts: 104	Re: 25mV readings? Off the FAQs Shearwater products use wire that is white or white with a brown stripe for ground (negative). They will have three white wires that are interchangeable and three colored wires for positive. Keep the board informed as to how you get on - I have to do mine yet and I am piggy backing them into a rEvodream as well so i have the HUD!
(Offline)

20th February 2008, 15:30	#6 (permalink)
OceanOpportunity for a world of water Current Rebreather/s: Other CCR Dolphin Home Build Other Rebreather/s: Not Bought Yet Inspiration Classic Other CCR Dolphin Home Build Join Date: Nov 2006 Location: Providence, RI USA Posts: 544	Re: 25mV readings? Problem solved. I can't honestly say what the specific issue was, other than that I tried several apparently wrong combinations of wiring. Generally speaking, I found it somewhat strange that there are not very clear instructions on how to wire the cable up. You don't have to be an electrician to figure it out, but considering that most folks have a VERY limited knowledge of electical circuits, a more detailed set of instruction would be helpful. Perhaps I'll work something up. Anyway, short story is this... In peeling back the outer cable sheath, you will find a copper wire wrap for strength down the cable, six colored wires, and an internal strength member. Some trial and error with one cell will lead you to quickly identify which wire is for which cell. Mark them. Now this leaves three unused wires. As it happens, the three cells share a common ground. Once the ground is identified, all 3 grounds tie in here. Clean it all up with some shrink tubing, and you're good to go. Double check mV's on the computer to read 10-13mV. Also double check that the cells are properly identified as 1-3 by unplugging one at a time. I permanently ID my cells and corresponding Molex connector by melting small holes in each with a soldering iron. Ex. 1 hole in molex and 1 hole in teh top of sensor 1, to denote sensor 1, and so on. good excersize, and now on to diving! Quote: (Originally Posted by Divein) Off the FAQs Shearwater products use wire that is white or white with a brown stripe for ground (negative). They will have three white wires that are interchangeable and three colored wires for positive. Keep the board informed as to how you get on - I have to do mine yet and I am piggy backing them into a rEvodream as well so i have the HUD! __________________ Michael Lombardi Oceans of Opportunity www.oceanopportunity.com Elected Director, Society for Human Performance in Extreme Environments MN'07, The Explorers Club Project Manager, Diving a Dream
(Offline)

20th February 2008, 16:07	#7 (permalink)
SeaBass Thom Susko Current Rebreather/s: Megalodon Ray Home Build Other Rebreather/s: Not Bought Yet Ray Home Build Join Date: Jul 2006 Location: San Clemente, CA Posts: 232	Re: 25mV readings? Hi Mike, Any pictures? . Quote: (Originally Posted by OceanOpportunity) In peeling back the outer cable sheath, you will find a copper wire wrap for strength down the cable, six colored wires, and an internal strength member. Some trial and error with one cell will lead you to quickly identify which wire is for which cell. Mark them. Now this leaves three unused wires. As it happens, the three cells share a common ground. Once the ground is identified, all 3 grounds tie in here. Clean it all up with some shrink tubing, and you're good to go. Double check mV's on the computer to read 10-13mV. Also double check that the cells are properly identified as 1-3 by unplugging one at a time. I permanently ID my cells and corresponding Molex connector by melting small holes in each with a soldering iron. Ex. 1 hole in molex and 1 hole in teh top of sensor 1, to denote sensor 1, and so on.
(Offline)

20th February 2008, 17:14	#8 (permalink)
Divein Custom Title Allowed! Current Rebreather/s: Dolphin Home Build Other Rebreather/s: Dolphin Home Build Join Date: Jun 2006 Location: Yorkshire Posts: 104	Re: 25mV readings? Pictures would be good as I don't do too well with words!!! Are you saying that pin 1 (12 o'clock position under red dot) is the ground and all 3 white/brown cables link to it? Thanks
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20th February 2008, 17:52	#9 (permalink)
kiwi_diver Alias - Ray Mansell Current Rebreather/s: Other SCR Other Rebreather/s: Other SCR Join Date: Aug 2007 Location: Auckland, New Zealand Posts: 157	Re: 25mV readings? Due to conflicting info on the Narked@90 and Shearwater sites, I decided to take my fischer plug apart and find the numbers on the back of the plug. The centre pin is pin 1 and you must wire all three sensor -ve to this pin. The sensor +ve go to pins 2,3 and 4 consecutively. When looking at the end of the plug, with the pins sticking out at you, have the half shell on your left. The pin at 12 o'clock is pin 2, next clockwise is 3, and the next is 4. You should meter the pins out to your cable ends as the colours may differ between cables. this can be done with a small test lamp or continuity tester. My cable had no connections to the other Fischer pins, 5, 6, and 7. Since posting this, I've found that Martin from TecMe had posted this good picture on another thread: __________________ Ray. == Latitude 36 South, where the deeper you dive, the warmer it gets! == Last edited by kiwi_diver : 20th February 2008 at 17:56. Reason: Added Martin's graphic.
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20th February 2008, 18:12	#10 (permalink)
Divein Custom Title Allowed! Current Rebreather/s: Dolphin Home Build Other Rebreather/s: Dolphin Home Build Join Date: Jun 2006 Location: Yorkshire Posts: 104	Re: 25mV readings? That's really helpful. Thanks very much - time to get the soldering iron out this week-end!
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