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Topic: 1602 : problem of brightness ! Please Help Me ! (Read 1 time) previous topic - next topic


Yes i changed the code to original and i pluged it as a shield on arduino and still no light :s

jack wp

Well, sorry to say, it sounds like it may have gotten burnt out.
You have it plugged in and using same sketch that worked before. but it is not working now? 
May be time to order another one (and be more careful in wiring next time). Sorry, but we have all been there before.
Good luck, Jack


It looks like you have a "White on Blue" LCD. These must have a working backlight for you to be able to see the text on the screen.
Is the white backlight on or not? If it is not on when you simply connected the LCD as a shield without any wires, you probably managed to fry the backlight or maybe a component on the PCB.


A couple of things.
The AVR has analog input pins but doesn't have any analog output pins.
All the AVR output pins are digital and the analog input pins can be used a digital outputs.
The Arduino analogWrite() function outputs a digital PWM signal not an analog voltage.

The shield you have uses analog pin 0 as an input to read the keyboard buttons,
so you shouldn't re-wire the pins use analog 0 as a digital output to drive the lcd
as you explained in your first post.

By hooking up the power backwards it possible that something was damaged on the shield.
It is also possible that if you used A0 as an output and pressed a button, that the A0
pin could have been fried.

A few questions about what you are seeing now:
- Are you saying the EXACT same configuration,
(shield plugged into Arduino), EXACT same sketch that used
to work, now has no or a very dim backlight?

- Is the backlight very dim or completely off?
Turn off the lights to see, if necessary.

It is possible that the backlight transistor was fried.
From looking at your board, it looks like it should be easy to fix.
Can you read the part number of the transistor?
It is next to hole over by the contrast pot.
Also what markings are on the part next to it?
I'm assuming it is a resistor but what are the markings?

Given the lower power backlight requirements of the 16x2 backlights,
there are some options for repairing the board, should it be a transistor issue.
But first we need to know what transistor the board has.

--- bill

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