I changed a backlight panel once this way but the characters where gone, the actual LCD was finished forever. Couldn't get it right anymore. But anyway, I have enough LCD's to experiment so we'll see.ALso just changing out the backlight behind the element is not so much work, the LCD still gets back correctly in its place with the rubber conductors to glass and no need to change the all unit altogether.
Buying? What does it cost nowadays? From China just a few dollars, some time (within 2 weeks) and often free shipping. Looked it up, I paid $8.30 total order $24.28 for 6 displays. Still a bargain.
Okay, changing color. Just change the led? What if it's moulded into the diffuser? Does the new diffuser fit in the old frame? I would like RGB. How to invert the appearance of the character? Black like now or white like with a blue backlight? Afaik you'll need to change the character code of the LCD but I vagualy remember that swapping two data lines will do the job. I'm not sure though.
"just increase the current for the LEDs" to make it brighter?
How? Resolder the MB, change capacitors? Put in different resistors? Another transistors? Are we talking Roland D110?
Okay, have to get the PCB out to resolder R5....no way. Anyway, my D110 gives of 5.05 volt, enough for the backlight*check that that it gets some voltage to its module edges. Mine had 4V on it and it was quite dim. You may reduce the R5, so it will get 4.5V so you get higher light output.
pin one for the LCD is top left, pin 14 bottom right (not visible but obviously there ) of the LCD connector and pictue bottom right the little 2 pin white connector for the backlight* which you don't need anymore using the 1602 ERM 2.1.
The only problem here is the size of the display. I was hoping the 14 pin LCD with gaps instead of holes for mounting would just fit as the original. Should have read the specs a bit closer but then again, finding a similar lcd as the original DM029Z is almost impossible. I found a Winstar (called 1602D) but the MO was a 1000 pieces and I just checked the specs: It is like the ERM 2.1 30.0 mm and not 33.0 mm like the DM029Z.
As a matter of fact, none of the specs concerning size match with the old DM029Z display.
And also, can you tell me what you meant by this:
"the backlight "module" is a LED array of 36 LEDs. there goes 5V to the whole module."
I really thought you were kidding when I read this.