rjet
Junior Member
Posts: 17 
Country: USA
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Post by rjet on Apr 15, 2014 2:15:53 GMT
Any thoughts on why LED for one circuit suddenly stopped working. Tried to replace with similar LED but no luck. Know how to solder so I'm not thinking that's a problem.
The circuit works fine, the circuit breaker works fine. I just have to remind myself to check since the LED is not 'lit' when the circuit if "on."
What am I missing? (Besides a knowledge of basic electric wiring!).
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Post by sailbleu on Apr 15, 2014 4:26:04 GMT
You don't mention/show what kind of led's are involved , is it 12 volt or any other voltage with resitor. Picture ?
Also , don't feel offended , but you know they have pos and neg connecting . Long wire is pos. , short is........
Have you tried connecting the led to another circuit as a test , that way you can define the problem.
regards
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Post by Zanshin on Apr 18, 2014 13:42:43 GMT
It seems that you mean the LED on the panel itself that shows whether or not the circuit is "on". Those are simply wired in the back of the panel and if the circuit is on but the light remains off you will need to look at the back side of the panel. The simplest problem and solution is that the LED itself is broken, you can test that easily with a multimeter to see if there is any current going to it when the circuit is turned on. I'm not sure what voltage these are, but you can check another LED that is working to see if it is a 12V or if the circuit for the LED has reduced the voltage. On my previous boats the LEDs were accessible, on my new Jeanneau the LEDs are surface-mounted to a PCB that is attached to the panel, making replacement much more difficult and time-consuming.
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Post by rene460 on Apr 19, 2014 9:51:50 GMT
The red indicator LED's are normally about 1.7 volts and operate with a series resistor of 1000 - 2000 ohm to limit the current to 5 - 10 mA in a 12 volt circuit, unlike the high brightness LED's used in lighting applications.
If the LED is open circuit, the voltage will be 12 volts due to no current through the resistor. If the fault is the resistor, solder joints or tracks on the board, the voltage will be 0.
As sailbleu says the replacement LED must be the right way around. I am not sure how to identify this on a SMD. A normal discrete LED has a flat on one side in addition to the uneven leg lengths so they can be identified after wires are trimmed on the board. My 2009 Jeanneau also seems to have SMD indicators replacement of which makes watchmaking seem like heavy engineering, and you must not overheat the device while soldering. Definitely outside my eyesight class, even with a magnifier.
rene460
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