MK15 primary has died

Larre Ländin

Hello all,

This is my first post to this board, I have been a long member of the rebreather mailinglist and allthough bulletin boards are a good forum I miss the old email list. It just died without a warning :-(

I have a problem with the primary electronics in my Mk15. I don't know what revision it is but it's been working fine up till now. When I turn it on it seems to work, adding oxygen at a steady pase. The problem is that as soon as I turn on the primary my secondary goes nuts getting a backfeed from the primary straight over the sensors making the reading impossible. After turning off the primary the sensors slowly come back to normal levels and the secondary is working again.

I have checked everything visually on the board but I can't find any shorts or burns and everything is dry. I guess I could send the electronics for repair but I'd rather have new digital electronics instead.

Now to my question:
Besides KJ is there anyone else who manufactures and sells primary electronics for Mk15? KJs is really nice but I don't need the computer and all other goodies that comes with it.
Maybe someone has built their own controller and are willing to share the schematics for a small fee?

Best regards, Larre

caveseeker7

If you need to replace the electronics, Colkan in Australia builds 15.5.
The electronics are described here:
http://www.rebreatherworld.com/92978-post8.html
Don't know if they sell them individually, but worth asking.
Colkan International
Phone: 02 66445223
Fax: 02 85725292
cw@colkan.com

Also, you can check with Kevin Juergensen if your problem can be fixed.
May not be the electronics (pod) but the horseshoe board.

__________________
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.!"

Dave Sutton

Colkan makes the pods, I have one and it works fine as I wait for my HH pods. BUT!! My bet is that your pod is fine and that you have an issue with the horseshoe board. I'd *diligently* check that before worrying about the pod. Easiest thing to do would be to swap pods out for a fast-check and see if it gets better, but I would not BUY a pod to do that, I'd borrow one. When was your horseshoe board redone? If it's original, they corrode down the sensor wires right to the the board and they start acting nuts.

I have a spare REV-G analog pod (not for sale) and a good center section so if you need troubleshooting, feel free to send me center section and pod and I'll figure it out for ya. Then you can buy what you need. If you don't know what pod you have and it's one of the new old stock Mark-15's that were sold recently, it's a REV-G analog.

Dave

__________________
"Silent Diving with No Bubbles and No Politics".... www.nobubblediving.com

Larre Ländin

Caveseeker, thanks for the tip. I'll contact Colkan to see what they would charge me for a new primary and maybe a new secondary at the same time. Allthough the old analog electronics might be fixable it is still nice to switch to digital to get the easier calibration and more reliable setpoint.

Dave, nice to see you on this forum, the mailinglist got really boring when you went away

Good advice regarding the horseshoeboard, how could I have missed that? If I have some time over this weekend I'll have a look at it. If the problem lies in the CS a new primary wouldn't help much and I would still be confused (and poorer).

Thank you and best regards, Larre

Andreas Fabian

Dave Sutton

Hi Larre,

You ever get this sorted out?

Best,

Dave

__________________
"Silent Diving with No Bubbles and No Politics".... www.nobubblediving.com

heyydude

Larre,

You've got water someplace. There are about 8 places this could have happened. The only way to tell is by process of elimination.

Call me (814) 395-9509 and I'll walk you through it.

Or you can send it to Dave and I'll wait for him to call me.


Oh - one last thing: DO NOT DIVE this unit like this - the O2 Sensor signal is being corrupted, so you can't trust it on either end.


Kevin Juergensen
Juergensen Marine, Inc.

Larre Ländin

I am sorry to disappoint you Dave but I am a busy man, I'm doing major reconstruction on my house right now so my time for diving is quite limited. Don't worry I'll let you now when I've had a look at it.

Thanks for caring, Larre

Larre Ländin

Kevin,

Thanks for the tip, I'll go through the unit as soon as possible. I have allready looked for water in the most obvious places but I might find some more after more careful examination.

I'll also dig out the old schematics for the horseshoeboard and measure all ins and outs of the CS. Maybe that will show something.

Thanks for your tips, maybe I'll give you a call.

Best regards, Larre

Larre Ländin

Boy do I feel stupid...

Last week I finally had some time to look at the electronics of my Mk15. I had borrowed another Mk15 to try to change parts and see in what part the fault was. Quite soon I found that the problem was in my secondary and not in the primary or in the horseshoeboard as I had expected.

I had built a new digital secondary since my DS2 dive computer stopped working and I have never owned a non leaking original secondary. The new secondary worked when the primary was shut of and therefore I previously assumed that the problem laid in the primary. However when using the secondary from my friends Mk15 everything worked fine.

My previous experience from electronics tells me that a digital panel meters is much more sensitive and has no or very little effect on the system being measured while an analog meter, such as the one in the original Mk15 secondary, puts some load on the system. When working with the very low voltages from the sensors this could be a factor I thought.

Anyway I was lost and therefore I called my friend who had built the new digital secondary to get his perspective on the whole problem. After about an hour of fault seeking he found out that the signal coming to the digital board wasn't correct. But when connected to the original secondary everything worked??? There was only one place left where the fault could be, in the Bendix bulkhead.

The bendix had been soldered years ago and been used by another friend in one of his projects, I hadn't confirmed that it actually was soldered correctly. Off-course I had looked at it but since I didn't know the pin-layout in my head I assumed that the wires was soldered correctly to pins 1,2,3 and 6...

Let me just say that I now know the bendix pin-layout by heart and I will never assume that stuff made by others are correct!

Best regards, Larre

P.S. The correct pin layout is pin 1,2,3 negative sensor voltage, pin 4 common sensor positive, pin 5 primary battery positive, pin 6 primary battery negative.