Quote:
Originally Posted by Barrykgerdes
The LCD characters are not lit at all. If they are selected they just block the backlight. The contrast relies on the intensity of the backlight and shows as letters or numbers as black (grey?).
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The LCD segments themselves have adjustable contrast too.
This is usually varied by a voltage applied to the driver IC, which in most cases is simply done with a multiturn trimpot set up as a rheostat(voltage divider), more clever versions will have a thermister included for temperature compensation.
Im not familiar with the Magellan, what type of LCD has it got?
2 line x 16 character? or 2x20 or 4x20 etc?
The only photo's I've been able to find are small, but it looks like a 2x16, which is likely to use the very common Hitachi HD44780 driver or a clone, in which case have a look at the circiutry hanging off pin 3.