Elddis Crusader Interior light problem

[iainwiththesterling]

Hi all,
I've got a problem with my caravan habitation lighting. On the 12v circuit one of the led strip tapes (around the sunroof on a Crusader Tempest 2016) had a loose wire. In trying to re-solder it I've caused a lot of problems. Now all of the lights in the lounge area are dim and if I turn the nearside awning light on and then the offside awning light on, the nearside one goes out! The offside one is one dim, even when it is switched off!
I am thinking I may have shorted the led strip and so blown a relay. Does that sound likely? Also, how do you get to the relays? Are they behind the fuse board?
Many thanks
Iain

 

[GD485]

Disconnect the light you repaired and check the operation of the other lights.

Are the internal leds connected to a dimmer unit?

 

[iainwiththesterling]

Thanks GD485. There's no dimmer switch and I've disconnected the light I repaired but it makes no difference.

 

[Buckman]

I may be mistaken, but I think the issue may lie with the solder used as it may be creating a higher resistance for the voltage path. You cannot use a dimmer switch on most LEDS. Your best bet is to replace the whole strip? Should not be too expensive.

 

[GD485]

The strange behaviour of the other lights sounds like broken wire, possible negative.
Most multiple light circuits share common wiring. If the wiring becomes open circuit then the current finds a route through the other lights.This effectively puts the lights in series. This produces the dimmed output. This is common on vehicle electrics were the earth becomes high resistance or open circuit.

LED's can be dimmed. The conventional ac dimmers used in houses, change the duration of the mains cycle and the as a result the voltage. LED's require a minimum voltage to illuminate. So, DC is switched to provide a variable duty cycle with a constant voltage. The frequency of the switching is fast enough to fool the eye and be perceived as constant.
It is often seen on TV when car rear lights appear to flash, this is due to strobing of the TV frame interval and the led frequency coinciding.

 

[ProfJohnL]

Hello iainwiththesterling,

The symptoms you describe are difficult to pin down precisely, but it suggests to me that you may have one or more faults.

I have seen a similar lighting faults on caravans road lights wiring where a combination of lights should use a common zero volts return wire, but the wire's connection had become corroded which firstly meant the it had a high resistance, and whilst the lower powered side light would illuminate the higher powers stop an indicators could not get enough current so the barely illuminated and teh side light dimmed even further.

So checking the zero volt returns from each light fitting is certainly a good starting point.