Samsung LE32R87BD LCD TV Backlight fault

[goldieoldie]

Hi,
I have a samsung  le32r87bd lcd tv with a backlight problem
TV switches on,shows pic and backlight for 1 sec then continues with pic (can see by using a torch on screen) and sound  but backlight off after 1 sec.
Have changed power supply (changed all the usual caps on original board), inverter board,fault the same.
Have dismantled screen to expose backlight.
In that brief 1 sec when the backlight works the tubes only light up about 1/3 of the length of each tube except for the one near the middle which lights up the whole length.
The 24 volts to the inverter board is there ok
I cant think its the backlight tubes as surely they would not all fail?
Is there a feedback loop/shut down circuitry which is causing the problem as there are 4 pins labled dim error etc on the connector to power supply board.
Any body out there had this fault please or can help?
Cheers Pete

[ProDave]

the inverter is sensing there is something wrong and shutting down.

Check the connections carefully. Some use busbars to connect the common end of the tubes together. Check for bad connections.

A trick to keep the set working a bit longer can be to disable the protection curcuit, but if the tubes are that bad you will get a picture noticably dimmer on one side than the other.