AMCS problem solved, solution unknown

Just a quick story about our Alarm, Monitoring and Control (AMCS) system misbehaving.

Under normal circumstances, when an AMCS alarm is received, it will be easy to identify it in technical spaces as traffic light will be activated and a horn will be sounded.

One beautiful afternoon close to the lovely island of St.Marteen, I was called to identify why there is no visual and sound indication during the alarms.

After triggering one of the alarms, I could confirm that was the case indeed - no traffic lights or horns were getting activated.

I did have a same problem on my previous boat and the culprit was tripped breaker for the Light Signal Control unit (LSCU).

Naturally, first thing I checked in this case was the breaker and it was fine. After quickly inspecting the power supply and few suspicious fuses throughout the LSCU and ruling those out as a culprit, I had to dig a bit deeper.

I pulled out a drawing of the LSCU and checked what was going on.

It seemed to me that normally opened (NO) contact no.5 could be the one that is triggering the traffic lights and horn.

After triggering one of the alarms again, I noticed this contact was not closing.

Ok, where is the other end of this cable connected?

Upon checking the drawings again, I could see the cable in question inside the LSCU was connected to the output of one of the modules inside the AMCS distribution boxes, specifically MACHINERY ALARM TO LIGHT COLUMN SYSTEM.

Next step was triggering an alarm again and seeing if this output gets activated.

Indeed…it does not.

At that point, it seemed to me like I found the cause of my problem. But how can I be sure?

Thinking…

Got it!

If I short the normally opened contact no.5 in the LSCU, I should get traffic lights and horn activated.

After shorting the contact, I could see lights and horn go off and was pretty happy to come closer to solving the issue.

However, at this point, my hands were tied.

Next step in troubleshooting this problem would be to check why the output from the AMCS module is not getting activated and that would mean picking the AMCS brain.

It would mean getting inside one of the AMCS servers and checking the conditions for this output to be triggered. To be more precise, getting inside the programming app, I believe it was PAL (Programmers Application Language) Needless to say, I didn’t have credentials to access the PAL.

Hell, I didn’t even have credentials to exit the AMCS app and get to desktop 😊

So the smartest thing to do was to get in touch with the AMCS manufacturer ASAP.

Phone call was not answered and mail was sent.

Chief Engineer was prepared this problem won't be solved and decided we would be manned 24 hours, me doing 00.00 to 8.00 watch!

Oh, no, sir, we are not going there. No, no, no...

I was determined to get the indication for the alarms back up again, I was not sacrificing my beauty sleep :)

I had no idea what to do… like many many times in my life but I knew I had to fix it.

After contemplating potential solutions for 2-3 hours, I came up with an idea that was so simple that I felt stupid not thinking of it sooner.

Find something that corelates with the AMCS alarm occurrence and see if you can use that as a signal to trigger the LSCU contact.

Looking a bit inside the AMCS distribution box, I noticed the HORN OUTPUT 1 label on one of the contacts. There was nothing connected to it and it seemed it to me that this contact might get triggered when the alarms gets activated.

So, I triggered the alarm and Gods sent their blessing – little red LED switched on and this contact got activated indeed. Alarm got muted, LED went off and contact would deactivate.

It was a normally opened contact, just what I needed, so I just took the cables from the MACHINERY ALARM TO LIGHT COLUMN SYSTEM contact and connected them to HORN OUTPUT 1 contact and we were golden.

We had visual and sound indication again!

After a few days, AMCS technician logged in and inspected the servers and did find a bug indeed but I forgot what it was about. After he rectified it, I returned cabling to the original condition and it was like nothing ever happened, but I knew I was richer for one more great experience.