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?

skuller · 02-08-2008, 11:05 AM

hooray!!
thanks a lot bbalazs and turbocad6
the hump on the capacitor is not really there, total flat

I would measure the voltage today
The monitor can change brightness but I am not sure it's backlight intensity, since my xenarc has the backlight intensity and brightness option on the osd
While the lilliput only has brightness

Do you think it will work?

FusionFanatic · 02-08-2008, 11:19 AM

don't know if this helps, but on my EBY701 pressing the ">" button scrolls through the brightness settings (without needing to go into the OSD). if your 629 does the same thing then you could wire a switch to that button to easily switch brightness levels with one button push. good luck

skuller · 02-08-2008, 01:11 PM

Quote: Originally Posted by ComputerGeek

don't know if this helps, but on my EBY701 pressing the ">" button scrolls through the brightness settings (without needing to go into the OSD). if your 629 does the same thing then you could wire a switch to that button to easily switch brightness levels with one button push. good luck

Thanks for the idea.
The 629GL does the same thing.

But I removed the whole button to make it fit into my dash, and there are no space to relocate the buttons.

skuller · 02-09-2008, 03:53 AM

Okay, I tested the voltage between pink and white wire
It was 9.5volt no matter the brightness level was.

I might just relocate the button to the very back of the screen and wire a little switch connected to the -> button. (thanks to computerGeek for the inspiration)

bbalazs · 02-09-2008, 01:07 PM

Hmm, three white LEDs chained serial...
If the voltage does not vary with 'brightness', I suppose, it also operates with the panel alone...
Is there any 'leak' on the display (eg. sideways), where the original brightness could be judged during dimming?