Opencockpits Master Card Input Problem

[egkkman]

Looking for some advice please, to help overcome a problem with an Opencockpits (OC) Master Card (MC) powering a 737 home cockpit.

This relates to an existing setup that had spare inputs on J3 40 pin connector. The spare inputs were 11, 12, 14- 19 and 21 -29 all other inputs were allocated and working.

I have wired up a fire panel and have used the spare inputs for it. I connected the panel into two groups for the inputs. The switches on the panel face as one group, requiring six inputs and one ground and the fire handles themselves requiring nine inputs plus one ground. The handles were connected to inputs 21 - 29 plus their dedicated ground and the other six to inputs 14 - 19 and their dedicated ground. Input 13 is connected to the parking brake.

Using controlodor I noted down the input numbers for each switch and set up SIOC etc. No problem with this process at all.

I then left the sim before divorce proceedings ensued.

The next evening I thought I would try out my setup. Fired everything up but noticed the parking brake had stopped working.Then discovered that none of the group of six fire panel switches worked.

So, I have checked the continuity of connections from MC to panel, no problem. Double checked connections, no problem. Checked 5V supply to MC, no problem. Have inspected the 40 pin connector and can see no problem.

What is really strange is that inputs 1 - 9, 21 - 29 and 31 -36 work perfectly; those from 11 - 19 & have died. They do not show in controlodor or in the Prosim GUI where one can check switch states.Also all other input/outputs are working perfectly.To confirm all 9 fire handle switches are working and associated annunciators.

I am thinking that my MC has failed? Is this the most likely conclusion? Has anyone else had similar issues? Remember input 13 was working has now stopped.

I have read through various forums and the OC MC manual without finding an answer.

I have posted this elsewhere and will post the answer, good or bad on each forum.

Any and all help much appreciated.

Dave

[verticallimit]

Sounds strange. Do you have a higher voltage that can be run backwards through a light bulb or other harware. It is usually only a higher voltage that can destroy the digital inputs.

[Perik]

Hello Dave

If all other Input's works except Group 2 then there must be something
wrong with pin 20 (Common for that group).
You may have blown U10 (74541) and more specific pin 17.
Check that you have connectivity between those two pins (J3-pin20 and U10-pin17).

[egkkman]

Hi Gents,

Thanks for your replies, much appreciated.

@ Vertical Limit - This thought occured to me as I am running the annunciators from the OC output card. I have
checked the wiring and I cannot see how I could have caused this to happen. (Let's put the fire handle switches/lights to one side
as they work, I'll refer only to the problem switches). The circuit for the switches is completely seperate from the
annumciators, my fear was that there was a shared ground connection, but no.

@ Perik. I'll do the check you suggest, thanks. I guess if it turns out that U10 is blown, that's it for those outputs. The
question is, how did this happen? Is it possible it just stopped working or must I have caused it?

Once again thanks for your help.

Dave.

[egkkman]

I have looked at this issue in some detail now, following suggestions that pointed towards an IC failure. I have been unable to solve the problem despite following advice.

The Master Card is in Warranty but frankly I do not want to send it for repair and be without it for weeks and weeks to discover that I have caused the problem (not convinced I did but……).

I have bought and inserted a POKEYS card to run non working inputs (the forth in my sim now) and have decided to ignore the OC faulty inputs. I hope the rest continue to work as the LED outputs are being used for my Overhea, the seven segment displays for the MCP and servos for home built gauges!

I highly recommend POKEYS cards and the service from Wendy is second to none.

Dave

[fordgt40]

Dave

You say that you checked the continuity from the MC to the switches. Was this through the 40 way cable? I ask because I have had problems with at least 2 OC supplied 40 pin cables that were not crimped properly and as a consequence have lost inputs

Woth mentioning :)

David

[egkkman]

David,

Thanks for the suggestion, well worth mentioning.

I checked the continuity from switch to the appropriate socket on the 40 way socket, I also checked
it to the soldered point where the plug is connected to the MC board.

I did remove the back (retainer) of the 40 way socket and inspected the connections with a magnifying
glass, all looked good.

I made the leads myself from 40 way cable and 40 way sockets. I had a couple of disasters but found
that by using a vice to 'crimp' the cable it worked every time.

I am sure those inputs are kaput, just hope there is no further breakdown of the card!

Thanks again.

Dave