I think I have finally managed to convert an LCD monitor with a faulty backlight to LED backlighting. As is very common the cold cathode lamps or the inverter had failed so instead of a clear white light I was getting a purple sort of hue and not a very bright one at that.
This is a tricky enough job and the first 2 I tried, an old TV and a monitor, didn't survive the surgery, but this one seems to have. I need to finish the wiring, but early tests show a good image.
UPDATE - 1st April 2014
The inverter had failed and there was a tell-tale burn mark round one of the transformers on the PCB. I got the LEDs wired to a 14v feed from the power board in the monitor. A good hack I think, but a brightness control will need to be sorted out using a cheap PWM power control module.