I've made a discovery.. Possibly cause to Warning module failures.

[madgadget]

This is a really long post.. Im sorry it probably wont interest many of you, but it actually solves IMO quite a mystery in the Mercury world of warning modules...

I have always suspected that the previous owner of my engine failed to maintain its effectively. I soon learnt that turning on the ignition and hearing no alarms was not normal and there should be some kind of alarm to indicate all was well.

So a few weeks ago I traced the wiring for the alarm (A small Piezo sounder in the engine controls) and I then grounded its supply and in theory it should then start beeping. It did - kind of intermittently, and then it started to stay on. So today I decided to look further and pull sounder out and test it on the bench. Normal operational range is 5-15 volts, so I gave it ago and sure enough it was playing up. No problem found another on ebay.

So on I went this time looking to see why when the should only be a short beep from the alarm the warning module on the engine was in fact putting out a continuous signal.

So I did some tests on this rather pricey module only to find that as suspected its defective.

So I then decided to do what any self respecting techno nut would do and then try and pull the unit apart without destroying it and try to establish the cause of failure.

Now this is harder than it seems in this case. Mercury have potted the module in a little plastic case with all the electronics covered in a hard setting rubber compound. The reason for this is quite simple. Its an attempt to keep out moisture and stop vibration from damaging the unit. Down side is chances of serviceability = almost none.

I did however make an amazing discovery... With a bit of careful prying and pushing I managed to pop out the potted electronics as a single lump without destroying it in the process.

I also immediately noticed something rather strange. There was signs of moisture in the bottom of the supposedly totally sealed case, in fact before this picture was taken, it was wet. Not only that I could see cracks along the potting compound where I could tell by looking closely the PCB sits, and now we have a way for the moisture to get in and quite possibly kill the module.. Now to see if its possible to see this..

I then carefully stuck a small (!) screwdriver just below where I could see the PCB end, I levered this slowly up and to my amazement the whole lot started to come away from the pcb revealing the entire face of the lower side.

This almost NEVER happens and only happened for me as the potting compound mercury use is quite flexible. Most are brittle like fibreglass resin, and so would never do this..

Check this out. I believe I've just solved the mystery why these modules fail so often for so many people:

Water damage anyone!?!!!

Reason is surprisingly simple. They sit on the outboard engine in the same orientation as the first image above. Water/moisture whatever sits in it and cant go anywhere. Give it enough time and it makes its way into the electronics. Had they been fitted to the engine the other way up I'm almost certain it would never have been a problem!

So now I have to decide what to do. I'm going to have a go at cleaning up the underside and will try to re-flow some of the connections but I'm 99% sure its beyond repair which leaves me with a bill for ?200 (Im in the UK) for a replacement or perhaps the alternative is to DIY my own module as a direct sit in replacement.. I suspect it could be done for ?20 and I probably have everything I need to do this anyway, just need to sit down and do it...

Not a bad afternoons work I think!!!

 

[Maxz695]

Re: I've made a discovery.. Possibly cause to Warning module failures.

I sold a sensor on eBay for $20 yes your right mosture can and probable did corrode the module. Thats what keeps car companies and engine builders in buisiness. They sell part much like i Boats but there nice to have a roiund when you need them it would be great if the world built things to last forever but in the world we live everyone wants to make money. I,ve lived withouht much for so long I am very appreciative for the little bit of gradifcation from my hard work I do have you have indeed cracked a nut here and I,ll be happy to explain it to otheres but how do you inform the unimformed of this revalation before they altimatley suffer the consiquece of malfunction and finding iBoats forum? If we can solve that we got it made!

 

[madgadget]

Re: I've made a discovery.. Possibly cause to Warning module failures.

So true!!!

I have to say as an additional point is that the quality of the module itself is pretty poor. Several of the non corroded solder joints are incomplete and ripe for dry joints as well as total failure.

Even at low quantities I reckon if it were possible to identify the components on the uppers side I could probably make it for 1/10th of what mercury ask... But its unlikely I'll find out what they are and tbh an equivalent with a MCU or something would be much nicer, and more intelligent anyway!

 

[Maxz695]

Re: I've made a discovery.. Possibly cause to Warning module failures.

Kinda like the three motherboards I bought on eBay all NG a 25 cent capacitor could make it last forever

 

[madgadget]

Re: I've made a discovery.. Possibly cause to Warning module failures.

Ok well tried this morning to clear the board up. No chance its corroded beyond repair. So plan B I'm going to look into making my own...

 

[j_martin]

Re: I've made a discovery.. Possibly cause to Warning module failures.

Ok well tried this morning to clear the board up. No chance its corroded beyond repair. So plan B I'm going to look into making my own...

Shouldn't be too difficult. I'm pretty sure it just integrates the pulse trains from the ignition and rotation sensor, nands them together (one or the other = output. Neither or both = no output).
Tank sensor is or'd into that result for final alarm drive.

The EFI version just wire or's the water switch to the oil tank switch.

If you develop a schematic, you have a niche market, or lots of friends.

Hope we didn't lose the crowd.
John

 

[madgadget]

Re: I've made a discovery.. Possibly cause to Warning module failures.

I think I'm going to put the oil switch and water switch into separate inputs that way I can code different beeps to represent which one it is, rather than a generic one beep fits all!

I tend to get carried away with my ideas so I'm just going to try and make it work first!

 

[j_martin]

Re: I've made a discovery.. Possibly cause to Warning module failures.

I think I'm going to put the oil switch and water switch into separate inputs that way I can code different beeps to represent which one it is, rather than a generic one beep fits all!

I tend to get carried away with my ideas so I'm just going to try and make it work first!

I know what you mean. My wood heat boiler control look like a pinball machine. There's three thermocouple controls on it, in addition to several honeywell switch thingies. Hope to get around to replacing it with a PLC and remote readouts and alarms.

 

[joed]

Re: I've made a discovery.. Possibly cause to Warning module failures.

I think I'm going to put the oil switch and water switch into separate inputs that way I can code different beeps to represent which one it is, rather than a generic one beep fits all!

I tend to get carried away with my ideas so I'm just going to try and make it work first!

If that thing works like the one on my engine the water does not go through the unit. The water connects in parallel to the output wire from the unit. If the unit or the water sensor grounds the wire on the output the beeper sounds. Oil issue give pulsing beep. Water issue give continuous beep.
When mine failed it was in continuous beep. My temporary fix was just unplug the module and leave the water sensor wire connected.

 

[madgadget]

Re: I've made a discovery.. Possibly cause to Warning module failures.

joed you are correct, same for the reserve oil tank. Just a simple N/O output. My thoughts are to re-route these into a new module with something like the following:

B = .5sec alarm
P = .5sec pause
. = 0.2 sec pause

Oil Pump Failure BPBP....etc
Overheat B.B.B.B... etc
Water in fuel BBPPBBPPBBPP...
etc for all sensors

I hope that makes sense

 

[j_martin]

Re: I've made a discovery.. Possibly cause to Warning module failures.

They must have wired them 2 different ways. I've cut and pasted a few of these between engines, and the ones I've seen had the extra connection on the oil level sensor for the water switch.

I like the beep codes. If it gets much more elaborate, you'll have to publish a Q card for it.

 

[madgadget]

Re: I've made a discovery.. Possibly cause to Warning module failures.

You are right sorry I must not have been clear. The wire comes out of the warning module and is split as you say, one way to oil level switch and the other to the water module, its my intention however to separate these into their own for my reasons above.

 

[j_martin]

Re: I've made a discovery.. Possibly cause to Warning module failures.

MadGadget,
Have you done anything on this yet. I just ran out of spares.

Tried to bench test 2 units and got no beeps. I found out that they actually check for the presence of the motion detector. When breadboarded to my XR4, one worked, and one didn't.

On the one that worked, I then disconnected the motion sensor. On the next power up I got the beeps. After that, no beeps. Reconnect the sensor, beeps again.

Switchbox connection and tank connection makes no difference.

Some kind of magic I guess. If I dream up a spoof for the motion detector, I'll post it.

 

[madgadget]

Re: I've made a discovery.. Possibly cause to Warning module failures.

Sorry I've only just seen this. I've started on the code for my own one. It should work fine, but my engine is in bits whilst I do major service to it so I cant test it yet.

I will do it however. No way am I paying $$$$$$ for what was in the last box.

Ed