Systems Monitor Bilge Level...Schematic?

I finally pursued the Systems Monitor - INOP situation on our boat. It turns out that these things don't work if you remove the fuse...

I installed the fuse and at first nothing happened - which I thought was a good thing. Then, after a few minutes, sitting with a cocktail in my hand, the system started sort of cackling. It became more frequent as we sat there and occasionally we could see the Bilge Level light flicker. I went into the starboard engine room and lifted the float and the system responded appropriately with a light and the alert horn.

I checked the drawings that I received with the boat and "32 V. D.C. Ship's Batteries, Elementary Diagram" (CN-101-ED) (Sheet 2 of 2) refers me to CN-107-ED for the "Systems Monitor 12 Point Elementary Diagram". I have attached a photo of the Bilge Level Switches area on that drawing and have a question...

It has been about 47 years since I worked with electrical schematics and I want to be sure that I am correct in thinking that the drawing shows that the circuit is normally closed and would alarm if the circuit was open. Is that what is shown on the drawing?

If there is a bad connection somewhere between the float switches and the systems monitor, or a defective float switch, or a problem in the systems monitor box itself, these could all be causes for the intermittent alarm...is that the case?

Anyone had a similar experience with this portion of the system and have any suggestions? I have read here on the forum that there is a fellow that works on these, but before I send it off to someone else, I figured that I should check for the simple stuff first.

Thanks!
Nick

When we got our boat there was an additional switch installed in the cockpit lazarette. It kept going off as water sloshed around. The easy fix was to replace the bilge pumps with new.

Your issue will likely be in the Systems Monitor box. There are two vertical strips of relays. Look at the right hand side. The terminals are named.

The crackling sound is probably a bad relay. Or a relay with dry connections. If you have a newer SM, then you may have removable relays or they can be wiggled. Put finger lightly on relay and you can feel them click. Or hear them.

A new relay is $13. Left strip relays are different. Only swap with right relays.

Google Hatteras System Monitor for helpful assistance.

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Originally Posted by Nick in Manitou

I finally pursued the Systems Monitor - INOP situation on our boat. It turns out that these things don't work if you remove the fuse...

I installed the fuse and at first nothing happened - which I thought was a good thing. Then, after a few minutes, sitting with a cocktail in my hand, the system started sort of cackling. It became more frequent as we sat there and occasionally we could see the Bilge Level light flicker. I went into the starboard engine room and lifted the float and the system responded appropriately with a light and the alert horn.

I checked the drawings that I received with the boat and "32 V. D.C. Ship's Batteries, Elementary Diagram" (CN-101-ED) (Sheet 2 of 2) refers me to CN-107-ED for the "Systems Monitor 12 Point Elementary Diagram". I have attached a photo of the Bilge Level Switches area on that drawing and have a question...

It has been about 47 years since I worked with electrical schematics and I want to be sure that I am correct in thinking that the drawing shows that the circuit is normally closed and would alarm if the circuit was open. Is that what is shown on the drawing?

If there is a bad connection somewhere between the float switches and the systems monitor, or a defective float switch, or a problem in the systems monitor box itself, these could all be causes for the intermittent alarm...is that the case?

Anyone had a similar experience with this portion of the system and have any suggestions? I have read here on the forum that there is a fellow that works on these, but before I send it off to someone else, I figured that I should check for the simple stuff first.

Thanks!
Nick

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The switches are Normally Closed and the alarm will sound when the switch is open.

I have opened the Systems Monitor box that resides on the inside of the tilting lower helm box. It certainly is not the most accessible place for a system with an astounding number of connections!

The drawing I have (CN-107-ED) refers to a drawing (CN-108-ED) that I don't have. I was hoping to be able understand a bit more about what I was looking at by referring to that drawing. I would guess that the "-ED" in the drawing name refers to the fact that our boat is an Extended Deckhouse model, but I would also guess that there would be little if any difference between the way this model is wired and others of the same era. Does anyone have a drawing that looks anything like the unit in the attached photo? (I have not checked with Sam's yet, as I just dug into this today.)

I did notice in one photo I took that the circuit board shows a date of December 1, 1978. Our boat is supposedly a 1984.

ScottinSidney referenced vertical strips of "relays". I am not at all proficient in electronics, but when I think of relays, I think of the 2 white units I see on either side of the terminal strip at the bottom of the board. Please take a look at the attached photo and describe what I should look for if suspecting the problem with an intermittent bilge level alarm is resident at this location. The identifiers for all the connections on the edges are obscured by the wires themselves and as I get older, I find my neck doesn't turn more than 270° degrees in more than one plane at a time!

Also of interest is the item stuck to the upper right corner of the board. Newer modification of something perhaps?

It may seem that I am being lazy not just pulling the whole board out, but the idea of undoing all those wire connections, perhaps just to find out that the fault is elsewhere, doesn't make me eager to dive in.

In the mean time, I think the next step for me will be to test the bilge floats to see if they are doing what they should.

Thanks for any assistance and for your patience!

Nick

Hi Nick,

The design of the board is pretty much the same. However, one modification made to my board by "Hatteras System Monitor" 23 years ago was to take the board out and install holders for all the little black relays. The relays are the black oblong things in vertical strips. Yes the two white things at the bottom are also relays.

As you can see your black relays are soldered to the board. These connections can become dry or brittle with age. Or the relay could fail. This is why a previous owner of my boat had the System Monitor guy remake the board.

Under the wiring connections on the right hand side are names for ALL the inputs. One will be for the bilge alarm. (On my own my own boat I had a faulty black relay and took the opportunity to loosen and WD40 ALL the connections. You may find a squirt on the relevant relay will be enough to wet the soldered connections.

The adhoc relay top right was a quick replacement for a black relay and would do the same function. You may actually find this is for the bilge alarm. The wires look l like they are simply pushed into the old solder hole.

The black relays on the left side are essentially to do with the flybridge SM panel. These black relays are different.

The systems monitor guy is really helpful if you get stuck or need to understand. But at the end of the day repairing them is his business. Looking at his work from so long ago, he is pretty good at what he does and I understand used to work/design electrical systems at Hatteras.

Thanks Scott and Tim.

Scott, you suggest spraying the relays with WD40, if I understand correctly. If that is the case, would I spray the relays on the side that is visible in the photo above, or would it be better to spray the connections on the back side of the board?

Also, should I be using a WD40 product designed for electronics? I have some other brand of "contact cleaner" on the boat...might that work?

Thanks!
Nick

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Originally Posted by Nick in Manitou

Also, should I be using a WD40 product designed for electronics? I have some other brand of "contact cleaner" on the boat...might that work?

Thanks!
Nick

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https://caig.com/deoxit-d-series/

I know quite a few wrenchers that swear by it. They call it the "PB Blaster of electronics". I just hit the tach senders on my synchronizer with it (with Glendinning's blessing).....we'll see.

Thanks, Oscar, I had not heard of it before!

Nick

My dear old dad swore by WD40 for absolutely everything. So its what I like too and I can think of him when I use it.

But I am quite sure there are better products for the purpose.