Hello. i need a small help

This is about three LED indicators on a DVR. they are named as POWER, NET and HDD.



At the moment the POWER LED is not working. the NET and HDD LEDs are working fine.

so first i got the voltage readings.

i think the readings are ok.

then i did a diode test for all three LEDs and these are the results i got.


as you can see the working LEDs show OL in both direction. can someone elaborate this. Thank you so much.

 

It would appear the POWER LED is faulty.

 

I concur. To check, measure the voltages indicated by the red and green arrows below., when power is on.

 

Doing a diode test on an LED in-circuit is largely meaningless. You don't know what the impact of the rest of the circuit that is around it.

The right-hand solder connection on the POWER LED looks a bit suspicious and might be a cold solder joint.

Did the POWER LED ever work?]

Are these all the same color of LED? 1.46 V is probably too low to turn on a visible LED, so either the LED has failed as a resistive short (pretty rare, but not impossible) or something else in the circuit is either clamping the voltage or otherwise preventing it from developing full voltage.

It should be a simple matter to desolder the LED from the board. That will let you test the LED directly to confirm whether it is good or bad, and also let you test the board without the LED load to see if it is generating enough voltage and current to drive the LED.