puzzleing problem with an LED

[pbmm]

the other day i bought 6 led s in a packet for the new station lighting and on checking them with a led tester they all passed muster and worked ok so i then added the wire tails and ran the wires back to the resister circuit board as per my normal procedure two leds to one 1k resister i then checked all the solder joints and eyeballed the whole thing over just to make sure all was as it should be . but on switch on only one led would work so every thing was stripped down and checked again but on re assembly i got the same result after some head scratching and 4 hours later it transpired that one of the leds would only work on its own but when connected into the system would cause all the other led s to switch off now as they are all wired correctly and when the offending one is removed every thing works fine can any one tell me why please as ive never had this problem before

 

[Beddhist]

Perhaps this LED's resistance is lower than the others, so it draws all the current, leaving not enough for the others?

 

[PhilP]

As I read this, you have a 1K resistor, two LED's in ?parallel?, this times four, across your supply. ??

What supply are you using?
What voltage does this supply produce?
What else (if anything) is it supplying?
AC or DC?

 

[fridge]

I just tried to download this program. Both "Malwarebytes" and "Norton 360" blocked it. Still, there are plenty more sites where you can find such tools if you just google.

 

[pbmm]

having spent some time on this i final did what i should have done in the first place opened another pkt and tried another led bingo it worked first time and the original led went into the spares box but i also wish to thank you all gents for your input and yes i did work out its values too thank ou all malcolm

 

[PhilP]

So, presumably, a different batch (or more likely specification) LED had got into the first bag then..
Glad you are sorted.

 

[PhilP]

Sounds like it Phil....to some sellers..a Led is a Led is a Led...... :

Some of my customers call them bulbs would you believe..or LED bulbs)

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Yeah, know what you mean there..
DON'T get me started on 'warm' white, versus 'cool' white LED's!! : :

 

[GAP]

So, presumably, a different batch (or more likely specification) LED had got into the first bag then..
Glad you are sorted.

Or he fell victim to that bane of electronics technicians the "production spread" where all chips are made to a spec with tolerances and some are right on the extreme which leads to poor performance.