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Component indentification

jkgr

New Member
Hello, this is a small pcb from a transducer cabling from a raymarine dragonfly 4 pro fishfinder/gps. This small pcb is subpart of the transducer cabling and it is enclosed in a cylindrical rubber as you can see in the photo and it is located a few inches from the connector that you insert to the actual fishfinder. After an overvoltage issue i had on my boat i suspect that this component failed.
So, I would like to ask:

1) What is this component's purpose
2) How to test it
3) What happens if i try to bybass it completely
4)If you can help me find the same or an alternative

Thank you !
 

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dr pepper

Well-Known Member
Most Helpful Member
It looks like a powerline filter, to stop noise from going to or comming from the transducer.
To make that fail theres a high chance that something else os blown too, as it would take a lot to damage a differential choke.
The unit might work without it, but the readings might well be well off.
 

ronsimpson

Well-Known Member
Most Helpful Member
The "WE" makes me think it is made by Würth Elektronik.
This picture is not right but is the surface mount newer version.
120084
Inside it looks like this:
120085
 

ronsimpson

Well-Known Member
Most Helpful Member
Measure the resistance from bottom left to bottom right wire or post. The resistance should be under 10 ohms probably under 2.
The top two pins should have the same resistance.
If one of the wires is "open" that is not good.
120086
There is a slim chance that the solder job under the part is bad. Try measuring from PCB pad to PCB pad (left to right).
 

dr pepper

Well-Known Member
Most Helpful Member
I bet its fine, as the circuit path being just copper wire, its most likely if it was open that the thing would be charred to a crisp, uless you had a very high current spike which made the wire blow like a fuse, even then there'd be a skidmark of somesort.
I'd hazard a guess that 102 means 1000uH or 1mH.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
I bet its fine, as the circuit path being just copper wire, its most likely if it was open that the thing would be charred to a crisp, uless you had a very high current spike which made the wire blow like a fuse, even then there'd be a skidmark of somesort.
Mostly that would be true, but 'occasionally' such coils are wound too tight, and the wire can fracture where it goes across a sharp corner - I've sometimes managed to repair such breaks, where it's accessible enough to tin each end of the wire and solder a small piece of wire across the break (or, if it's very accessible, run a new wire from the pin to the broken end).

But certainly such devices are EXTREMELY reliable, after all it's only a couple of pieces of thickish wire wound round a core.
 

dr pepper

Well-Known Member
Most Helpful Member
Actually I get that on industrial contactors occasionally, I assumed it was bemf causing it to fail, maybe its as you say stresses weakening the wire during manufacture.
 

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