sudomod

Hi all,
this is my first post and also guide, and I want to show how I managed to add a brightness adjustment to the LQ035NC111 screen that is fairly common among GBZ builders.

I found out that one of my screens had the smaller FPC ribbon part broken, and the small 2 wire part of the ribbon is for powering the LCD backlight. So to repair my broken screen i tore it down pretty much as far as you can go with the screen; but from this I experimented with the screen since I thought it was borked.

[youtube]https://www.youtube.com/watch?v=BSTuSFl ... e=youtu.be[/youtube]


What you'll need:
-Soldering Iron (Duh)
-Potentiometer of choice, Im using a 10K pot


Steps:
1. Remove the kapton tape that covers the 2 leads on the FPC connector
2. Desolder, with low heat, the positive lead. they are labeled on the FPC


3. Solder a positive wire from the FPC to Potentiometer (input)
Solder a positive wire from Potentiometer to the backlight connector (output)
Solder a ground wire from Potentiometer to FPC connector


now you should be able to roll the Potentiometer wheel to control the voltage coming into the screen.
currently working on a video that will hopefully be easier to follow, and will post a link when done.

This may be on the difficult side, but I have tested it out and it works very well.

Otherwise if you have questions, let me know, I am not very prominent on here but I check Instagram daily and you can connect with me there and check out my current Gameboy pocket RP3A+ build.

My handle on Instagram is: tymarbry

Your images aren’t working.....
(Well not for me)




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geeze, that's embarrassing. turns out amazon photo doesn't like to share image links, but they should be fixed now!

Nice!

Excellent hack. I'm no electrical engineer but I was under the impression that you'd need a 555 timer or something to PWM the LED backlight enable pin. I guess not?

I guess you could use an ADC (analog digital converter or something along those lines) to control brightness, but given that the backlight can be directly adjusted by adding resistance to the voltage, you can just wire inline this potentiometer.

As I understand it, also using the PWM you wont get immediate brightness control and it seems much more complex. I tend to keep things simple if possible.

Great video and very well explained! Thanks for this!

Hey guys,

Just a heads up.

This mod will not work on versions of BEST controller which have a CL6201 LED Driver chip (7001) e.g. BEST012-3.5D-V1.1.

The reason being is that the driver chip samples the current and the voltage coming from the backlight, any deviation triggers a safety shutdown.

You can find some specifics in the driver’s datasheet.

Having the whole current going through the potentiometer is not an issue? It's not toasting it?
Also does it not increase the current you would have used on lower brightness?

The thumbwheel should be located on the PWM/CE/EN pin (instead of the usual PWM) of the LED driver for best efficiency (I think).
On KA2707 that's called CE pin. Looking at my schematic I think a wheel potentiometer could be used there instead of the PWM from the SoC (on RetroStone2)

Great video