lilliput backlight pinout for manual dimming

**skuller** · 02-06-2008, 11:56 PM

It's the new 7" lilliput 629 with led backlight
I am looking for the inverter pin that control the backlight.

I read that the intensity of the backlight can be adjusted manually by reducing the voltage on the inverter backlight control (0v brightest, 3.3v dimmest)

anybody know which cable I should tap into?

**bbalazs** · 02-07-2008, 08:07 AM

Can we see the other part of PCB? It seems to be a ccfl backlight.

**skuller** · 02-07-2008, 11:03 AM

here ya go

darn it, you sure it's not led?

**bbalazs** · 02-07-2008, 11:44 AM

Not absolutely sure, but very likely.
Can you remove the PCB on the second (newest) picture?
If there is a small transformer on the other side, near to the 2-pole connector I have mentioned (white/pink), it is CCFT.

**skuller** · 02-07-2008, 01:05 PM

I will check it out as soon as I get home.
Hope it's led since that's the main reason I bought the monitor.

I'll post the other side picture this afternoon

**turbocad6** · 02-07-2008, 01:41 PM

that pink & white pitail with that connector def looks like a ccfl high voltage lead, like was said, the other side of the board that it connects too will tell for sure, but I'd say it's a ccfl unless they just happened to use the same conectors & wires for th leds too, which isn't imposible, but highly unlikely at least.

**skuller** · 02-07-2008, 03:36 PM

here's the back circuit board

the pink-white wire connected to the other side of the board on the right side (as I marked)

so, what's the verdict guys? confirmed ccfl?

**turbocad6** · 02-07-2008, 04:52 PM

hmm, I still can't say for sure, I think those 2 round things may be a transformer, but look differnt from what I'm used to seeing, zooming that area you circled may help...

**skuller** · 02-07-2008, 06:13 PM

how about this one?

**bbalazs** · 02-08-2008, 05:50 AM

Skuller, you won, it is definietly NOT ccfl. We were wrong.

I think those two coils serve as choke coils (or what is the appropriate expression) that eliminate the current peaks because the PWM.

In this case, the situation is better, because ccft needs a minimal voltage to maintain the gas ionized, but leds could be dimmed down until total darkness.

Now, returning to the original problem, I think it is possible by reducing the voltage that goes toward LEDs. Can you measure the voltage on that pink/white connector under working condition?

Is the monitor able to modify the brightness itself? I asked, because my lcd tv just operates with the panel, not ccfl as 'brightness control'.

edit:
Is it just an illusion, or reality that the large electrolythic capacitor has a hump on the metal top?