Water level guage

[martinchambers]

I am trying to get our water level guages to work. Bavaria oceans 47 but I think these things are common across the range. Photo shows cable connection and second photo the switchboard. When pressed, the water level gauge moves but shows  no reading. Boat is 2002 and previous owners have done things, and the wiring is a mess. Third photo is gauge with wires. Can anybody tell me what I am looking for to check this is correctly connected. Where should the wires go?

[Yngmar]

The wires go to sensors at the top of the tanks. You will find these are connected with the same flat cable connectors as on the PCB end in your photo (near the tank sensors). The sensors are just a bunch of metal rods and don't really fail, but the connectors were all slightly corroded on our boat. Just re-plugging them a couple times cleaned them enough to work fine.

I then pressed a bit of silicone grease into the connector pin holes to keep future moisture (and corrosion) away and haven't had problems with them ever since.

[martinchambers]

thanks, I just checked and those wires were very dirty, in fact as i cleaned one of the terminals broke off. I'll have to sort this out back in the marina later but seems you are correct this is the problem. Interesting that it all looked good until i pulled the connector apart.

[Lyra]

I don't know about newer models, but the electrical system of older models is poorly executed, using non tinned wires, which corrode over the years. the corrosion goes deep into the wire insulated parts, not only close to the ends.

[martinchambers]

Yes, the connector and the wires at the tank were badly corroded and I have now fixed this. The guage still does not work however and I suspect the switchboard end. It is a tangle of modifies wires and I wuspect a previous owner has thought it not working so left it as a  mess.
What id like to know is what goes where from the circuit board to the guage.

[Yngmar]

The black cable with the flat plug and the thin wires goes to the gauge on the DC panel: https://www.svb.de/de/platine-fuer-verteilertafel-v16-v20.html#fullSize

The way the system works is, pushing the tank button under the gauge sends a test voltage to the sensor and then the circuit board reads which (how many) of the rods in the tank are touching water (and thus return a non-zero voltage reading). This is then converted into an appropriate voltage to drive the gauge to show the corresponding readout of empty, 1/4, 1/2, 3/4 or full.

With this information you should be able to troubleshoot where the problem lies. Looks like you've also got some corrosion on the circuit board. The link above is to the circuit board, but it's apparently no longer available. Might just need to be cleaned up. Presumably you have already checked the connectors on that side - if not, you know what to do

[SYJetzt]

as Yngmar mentioned, maybe you will have a contact issue on the side of the circuit board. It´s not only the connector on the circuit board itself, but the connector on which the ribbon cable is crimped on too.
Try to move the ribbon cable gently in the connector, and/or use WD40 to improve contact.
I had the same problem with the gauge. The connectors were badly corroded. At the end i ordered new Crimp-Connectors, cut the ribbon-cable back 3 cm and crimped the new connector on, which was a simple job without using any special crimping tool. If you need a long term solution apply some silicone grease before crimping the ribbon cable on, as suggested by Yngmar.  The connectors are "STOCKO RFK2" type, which i sourced from the distributor in austria for less than 20 Euros. Try google to find your nearest distributor.

[Lyra]

It might be worthwhile to  look at the back side of the PCB.
I had once a problem with one of the PCBs on the switchboard, traces were so badly corrode that they barely conducted and I had to solder some jumper wires to bypass them.

[diverphil]

hi, looking at the photo of the pcb it looks like there is green corrosion on the pins of the first connector to the pcb (marked tank 1). may be worth testing the joints where the pins go into the pcb.
hope you find the fault
phil