LG Flatron L194WT inverter board; light flicker

[uengin]

Hello everyone,

Here I have the board only from a an LG Flatron L194WT. When a friend gave this to me because it was playing up and I didn't have time to fix it nor did I want it taking up space, so I just took the inverter board and tossed it out. So, for a learning experience I'd like to fix it.

Tied BL_ON high to 5V rail. Hook it up to known good CCFLs. CCFL light flickers and slightly fainted. Capacitors are SAMXON, no bulging evident but not always have to bulging. Voltage rails are all good.

I know I can test component, but I don't want to start testing at random. Where to start trouble shooting?

Thanks everyone.

[budm]

Re: LG Flatron L194WT inverter board; light flicker

Post good clear pictures of the board, both sides, will be a good start.

[uengin]

Re: LG Flatron L194WT inverter board; light flicker

yeah, photos coming soon

[selldoor]

Re: LG Flatron L194WT inverter board; light flicker

You may need another jumper resistor from 5v to dim (if there is a dim pin)

Test the secondary windings (Ohms 2000 range) on the inverter transformer/s

[uengin]

Re: LG Flatron L194WT inverter board; light flicker

Ok, here's the photos. I don't know if it's the lighting or what, had so much trouble getting focussed images. Probably because I'm using a Nikon, I much prefer the Canons... Anyway, that's another story.

[uengin]

Re: LG Flatron L194WT inverter board; light flicker

You may need another jumper resistor from 5v to dim (if there is a dim pin)

Test the secondary windings (Ohms 2000 range) on the inverter transformer/s

Ok, so there is a DIM line. Question is is it active high or active low? Pulling it high seems to me it will make it dim out? No?

[Davi.p]

Re: LG Flatron L194WT inverter board; light flicker

Dim is not a digital signal, you have minimum brightness at 1,5v for example (i don't remember) and maximum at 3v so test which voltage you have with the resistor to 5v. Anyway i see there are output values printed near output connector, test those and compare to what's printed.