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Discussion Starter #1 (Edited)
In celebration of the fact that mk15x rigs have a shiny, new, dedicated sub-forum here on YD, here's a unit specific post to kick it off.

Anyone with one of these rigs is liable to suggest that they are a labor of love. However, once you go over the rig carefully, it *is* possible to run out of things to work on... Indeed, I found myself in such a place several months back. I decided to make a replacement horseshoe board. I figured if I hung it up on a wall in my dive room, I would never need it :teeth:

Anyway, the product of that effort is attached (no resistors soldered in place yet!). The process was approximately: Adobe Illustrator to arrive at the traces, print the traces on blue "iron on" circuit transfer paper, iron the circuit onto copper clad, etch with your favorite etchant (I used muriatic acid and H2O2), use a Dremel to cut to shape, acetone to remove the toner, treat with liquid tinning solution to protect the traces... et, voila... (if you do this enough times, one will turn out, or you can just pay one of the many instant pcb places to do it for you, but where's the fun in that :D).

Chris
 

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Jesus don't want me for a sunbeam
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Good effort. I know what you mean... some new hose adaptors are my next project.

Woo hoo... when did we get the Mk15 forum? Well... get it more active and I won't have any reason to go on Burgerworld again :D
 

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Woo hoo... when did we get the Mk15 forum? Well... get it more active and I won't have any reason to go on Burgerworld again :D


Yippee!

I've got a Mark-15 in the shed as well as a bunch of parts of odd varieties.

Nice to find some other users, as well as a forum.


Nice job on the horseshoe board. You sticking with original pod or?

I was going to remove my board totally and use a Shearwater controller and HUD on mine. Still mulling though.


Bubbler
 

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Discussion Starter #6
I have a Delrin Hammerhead as primary and a Shearwater Predator as secondary. I like this setup a lot. As I have the Colkan mod between the sensor bridge and the horseshoe board, the center section should be free from the effects of corrosion for a very long time.
 

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Using what cells? I was working to use a Shearwater as a secondary but was stymied by the 25 MV cells needed by my pod. The SW has a range of MV's that it will accept as a valid signal at 100% for calibration, and the 25 MV cells exceeded that level. Was going to add simple resistors to the input to the SW but never implemented it. I did manage to add a 4th cell to mine though, feeding a fisher cable to a SW as a 4th cell deco computer.

Have had poor luck personally with the HH (fitted to an Inspiration in my youth), and have witnessed enough others having issues that I would not buy one myself, but when they work they are capable enough. They would allow a standard cell to be used, so the SW would work methinks.

Really, I think I am going to wait for someone to sell an entire Shearwater controller package out of a rEvo when they upgrade to the new system for them, and then rip out the hoseshoe board, wire three cells directly to the SW controller and add a SW HUD and be done with it.

Bubbler
 

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Discussion Starter #8
R-10DS equiv from AII. I put resistors in-line with a Bendix cable that I custom built for the application.

I've tried four flavors of Hammerhead, Delrin is the best so far :D.
 

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Why not just use standard cells? The HH will calibrate almost anything, no?

Looks like my resistor idea works in practice as well as in theory though. Thanks for the data point.

As for 4 HH flavors... I hope you got all but the first for free.
Insanity is attempting the same thing again and again and again hoping for a different outcome!


Bubbler
 

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Discussion Starter #10 (Edited)
The HH primary has resistors that sit in the pod -- so I had to either add or subtract resistors. The mk15 cells have, at least in my experience, more stability and longevity compared to standard cells.

Nothing in life is free :D.

C
 

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That's for certain. The R10DS cells were great, lasted forever, and never ever failed. Hope the replacements work as well.

Good work building up the Bendix cable with resistors. Bruce P and I spoke about it at length a few years back, selected the resistors, I had them on the bench, and then <sigh>: Never actually made time to solder the system up. This might be the shove I needed to break inertia.

Bubbler
 

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Discussion Starter #12
The R10DS cells were great, lasted forever, and never ever failed. Hope the replacements work as well.
I've had three PSR-11-33-NM1 AII cells (Teledyne R10DS equiv) on my rig for 2 years now. They've worked flawlessly during this time. All three were linear to 2.5 ppO2 on a cell checker last week. Time to start rotating them out, just because, though. Fingers crossed that the next ones I pick up from AII perform the same.
 

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Interesting idea on the resistors. Any specs on what you were thinking of using? I'm considering putting a Heinrichs Weikamp monitor on and it maxes out at 160mV which is just on the threshold of 1.6 on a high output cell.

I also had thought of removing the resistors from the HH pod until I opened it and it looked like a jar of spaghetti inside :(
 

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Good deal. We were getting 3+ years reliably out of the R10DS cells, so that makes sense.

Large cell: lots of anode + lots of cathode + lots of electrolyte = longer life.

I'd wonder why the other rigs use 11mv cells and not these? Might it be just that the most available cells to experimenters and garage shop builders "of yore" (like Smithers, Leon S, P Ready, Dave T, etc) were R-22MED's from Teledyne "back in the beginning" and then they morphed into R22D's, and then... ??? Maybe it's not the best way to go "just because it's always been done that way" maybe?


Bubbler
 

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Discussion Starter #15
Interesting idea on the resistors. Any specs on what you were thinking of using? I'm considering putting a Heinrichs Weikamp monitor on and it maxes out at 160mV which is just on the threshold of 1.6 on a high output cell.
I used 100K resistors.


I also had thought of removing the resistors from the HH pod until I opened it and it looked like a jar of spaghetti inside :(
I hear you. I did my own and it also has that appearance.
 

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Discussion Starter #16
I'd wonder why the other rigs use 11mv cells and not these? Might it be just that the most available cells to experimenters and garage shop builders "of yore" (like Smithers, Leon S, P Ready, Dave T, etc) were R-22MED's from Teledyne "back in the beginning" and then they morphed into R22D's, and then... ??? Maybe it's not the best way to go "just because it's always been done that way" maybe?
Things that make you go "hmmm." Some of those people used to roll their own sensors.
 

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None of those did, but guys like Walter Stark did for sure. Electrolung sensors were made fresh every day. Walter told me that the main reason the Electrolung got the nickname "chrome death" was because lazy divers woul not make up fresh paste every day, but would simply adjust the trim pots up for a second (third, etc) day until they ran out of calibration adjustment before making up fresh paste. Sort of the 1960's version of not changing your cells on schedule. Remember that these were polarographic (Clark) cells, changing current and not voltage in relationship to PP02.

The Electrolung ones were supposed to be prepared by the diver daily :eek:

Bubbler
 

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I used 100K resistors.
.

That confirms what Bruce suggested I use.
I just looked for the bag of them he sent and they right where they were two years ago: unopened in my desk.


Remember this handy way to memorize the resistor color code?
I wonder if they still teach it in high school (where I learned it):

Bad Boys Rape Our Young Girls But Violet Gives Willingly
Black, Brown Red, Orange, Yellow, Green, Blue, Violet, Grey, White
0,1,2,3,4,5,6,7,8,9


;-)

73's

Bubbler
 
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