LED's

[Baldhead]

I promised my granddaughter some fairy lights for her bedroom, they are blue LED's type, they appear to work in banks of 7, the first 7 light, the second 7 don't, third 7 light, fourth 7 don't, fifth 7 don't, sixth 7 don't, eighth 7 do, etc etc, has anyone got any idea how they are wired? The wire is 2 core and they appear to be wired in series but I am only guessing, I would love to repair them for her as anything that breaks is brought round for grandad to fix, she calls me the fixer.

BH

 

[Myfordman]

How are they powered? battery or mains? If mains I suspect that they run half on the positive cycle and the others on the negative cycle and something has gone awry in the driver circuitry.

 

[misterfish]

We had some that were similar (but fewer overall leds) and these were wired in groups of 5. Each group of 5 was wired in series and all of these series were wired in parallel. The power supply provided 24v dc and I assume by having 5 in series they could be made using '5v' leds. If 1 led fails then its group of 5 no longer illuminates.

Misterfish

 

[joethedrummer]

What a puzzle these things can be !!

I know how grandkids realise we can fix anything,,,,,so I just slip off to the shops and get something better than I was presented with,,,,,and proudly say " Granddad has made you a better one ",,,,,it has worked so far although they are starting to give me funny looks !!!
,,,joe,,,,

 

[Baldhead]

What a puzzle these things can be !!

I know how grandkids realise we can fix anything,,,,,so I just slip off to the shops and get something better than I was presented with,,,,,and proudly say " Granddad has made you a better one ",,,,,it has worked so far although they are starting to give me funny looks !!!
,,,joe,,,,

Joe isn't it nice when anything and everything can be "fixed" by grandad, it gives you sense of worth. My eldest grandchild is 7 going on 27, she's bright as a button, she wouldn't fall for 'the replacement trick' although I honestly think she would play along with it, that is until she got home where she would ask her mam if grandad had just bought a new one!

Myfordman has PM'd me some info into how they are probably wired and how to possibly find the fault, so I will dust the old multimeter off and attempt a repair, I do however think I may have to be honest and say, "Granada can't fix it this time". I know she will be sad but I'm sure after a few minutes all will be forgotten.

BH

 

[Racers]

The sections that don't light will have one LEDs open circuit so you need to find which one is faulty and replace it, difficult and time consuming to do.
I would replace them.

Pete