Electric lamp with 18 leds blinks abnormally and got shorted

N

ngzek

Member

• Jun 21, 2016

• #1

Lamps with 18 leds suddenly got shorted after some dim blinks. whats wrong with it and which part is responsible? Please help

 

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H

hyedenny

Active Member

• Jun 21, 2016

• #2

ngzek said:

Lamps with 18 leds suddenly got shorted after some dim blinks. whats wrong with it and which part is responsible? Please help

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With all that detailed information you gave, my first guess would be that it suddenly got shorted, now it doesn't work, and the circuit board is the culprit.

 

alec_t

Well-Known Member

Most Helpful Member

• Jun 22, 2016

• #3

One or more of the diodes (those black things with a silver band at one end) is the most likely culprit.
What supplies the power for the lamp?

 

N

ngzek

Member

• Jun 22, 2016

• #4

Alec-t I will replace those diodes with equal values . I will be back with the getting result. Thank you all

 

M

MrAl

Well-Known Member

Most Helpful Member

• Jun 22, 2016

• #5

Hi,

Do all the LEDs blink at the same rate?
Or do they all blink independently, at different rates?

 

N

ngzek

Member

• Jun 22, 2016

• #6

Sorry I cannot remember exactly, they blink and all of them black out but not at the same time some leds last some minutes.

 

M

MrAl

Well-Known Member

Most Helpful Member

• Jun 22, 2016

• #7

ngzek said:

Sorry I cannot remember exactly, they blink and all of them black out but not at the same time some leds last some minutes.

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Hi,

Wow, in that case it could be the LED's are being driven too hard, as in too much current for each LED. You could at least check the current in some of the LED's to make sure it is within spec, which is probably 20ma or less.
I dont know yet what the oscillatory mechanism is yet, but when some LED's get over driven they start to blink on and off at unpredictable rates. Very very annoying to say the least.
The solution is to lower the current by whatever means is most convenient, and hope none burnt out yet.

 

N

ngzek

Member

• Jun 22, 2016

• #8

MrAI thanks its great to learn that 1. Too much current 2.normal current is 2ma/less for a led 3. Led blinks when over driven. Ithink there may be leakage to some diodes in the power supply lines. Okay I will check the currents on the power lines.

 

audioguru

Well-Known Member

Most Helpful Member

• Jun 23, 2016

• #9

You did not post a detailed schematic showing parts values. The schematic should also show the input which we guess is high voltage AC electricity? We need to know the RMS voltage and its frequency.
Your photo shows a simple circuit with only one red LED but another photo shows 18 clear LEDs and we do not know if they are connected to the same circuit or how they are connected. There are many wires shown on the photos but no labels describing what they are for.

Here is a sketch of a schematic similar to yours. Copy it and make changes to it using Microsoft Paint program so it matches your circuit, then post it here as your schematic.

 

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N

ngzek

Member

• Jun 23, 2016

• #10

audioguru By seeing this i can recognize every components inside the lamp circuit board. I think this schematic is exactly the same but the only little difference is there are two positive line in which one positive line is connected to 12leds and another is connected to all 18 leds designs to switch dimmer or brighter . Thanks for the schematic

 

dr pepper

Well-Known Member

Most Helpful Member

• Jun 23, 2016

• #11

That looks like a mains powered light, be careful mains is dangerous.