Help: repurposing a lcd power supply

[dany-boy]

Hello everyone:
The other say I was shopping in downtown Mexico city and scored these power supplies for dirt cheap (50 pesos / 2.8 USD). All of them work fine, both in voltage and current specs. Among them, there is an lcd power supply which has a high voltage output to drive the back-light. I would like to use this high voltage output to easily drive a clf in another electronics project. However, the HV output shuts down after a few seconds of turning it on. I suspect that the PSU has some sort of feedback mechanism that shuts it down if certain conditions are not met.

Here is the datasheet for the entire LCD: http://www.go-gddq.com/upload/2009_10/09102412529181.pdf. PSU schematics are in pages 22 and 23. High voltage supply is in page 23. With my limited electronics knowledge (I'm a high-school student) I can't quite figure out which conditions must be met. I don't just want to short the terminals in the HV output in case something blows up. Any help towards getting continuous HV would be amazing.
Should you need any more information I will be happy to reply.

Thanks for reading my post.

[rf+tech]

Hello dany-boy,

You are correct that there is a feedback path. Most supplies such as this require both CFL to be present. If one is missing/broken/dead, the supply senses this abnormal condition and turns itself off. If you have two CFL, try the supply again with both lamps.

As a learning exercise, I'll give you this hint: check the voltage present at the point where R853 and C853 connect to the base of Q806, when the one lamp lights briefly and when the lamp is off. What happens here?

Can you follow the schematic and see where this control signal comes from?

RF+ Tech