Megadrum by Japi - Documentation / Pictures -

[Synthex]

No. Do you use a resistor for the LCD backlight LED ?

No, i think i don't. Should I ?

I speak about the 470 ohms resistor on the board.

[japi]

I speak about the 470 ohms resistor on the board.

I have wired all resistors as per the picture of the board (pcb top) provided by you

http://www.japiwebcam.com.ar/japi/megad ... ard-16.jpg

[dmitri]

I speak about the 470 ohms resistor on the board.

I have wired all resistors as per the picture of the board (pcb top) provided by you

http://www.japiwebcam.com.ar/japi/megad ... ard-16.jpg

Replace the 470 Ohm resistor coming from the pin 15 of the lcd connector with a ~33-68 Ohm resistor.

[japi]

Replace the 470 Ohm resistor coming from the pin 15 of the lcd connector with a ~33-68 Ohm resistor.

Why? Is it bad designed with a 470 resistor?
It will be a nightmare to replace that 470, everything is very tight in that place, with the lcd and trimpot in place

[Synthex]

Please watch the datasheet of your LCD display.
It will give you the current needed for the backlight.

If the brightness of the backlight is too low,
you must replace the resistor by a lower value.

[gyro]

You can solder that resistor on top of the legs of the already mounted resistor ...
If :
R=470 ohms
R1= resistance needed
R2= resistor mounted on top of 470 ohms
you can figure out with : 1/R1=1/R+1/R2

that is : R1=(RxR2)/(R-R2)
but the resistor you have to mount on top of the 470 ohms will be pretty close in figures to the resistor you need.

My 2 cents

[efbe]

Replace the 470 Ohm resistor coming from the pin 15 of the lcd connector with a ~33-68 Ohm resistor.

Why? Is it bad designed with a 470 resistor?
It will be a nightmare to replace that 470, everything is very tight in that place, with the lcd and trimpot in place

Stupid question mabey, but did You check the polarity ??

EFBE

[japi]

Please watch the datasheet of your LCD display.

I'm attaching its datasheet

You can solder that resistor on top of the legs of the already mounted resistor ...

Do you mean that I solder directly a 33 ohm resistor on top of the other? In parallel right?

Stupid question mabey, but did You check the polarity ??

Polarity of what?
If you mean the lcd, theres no mistake, the pinout is the same, and i'm getting around 3.7v on the lcd legs corresponding to backlit. This lcd backlit was working with my previous board based on dmitris schema

[efbe]

Please watch the datasheet of your LCD display.

I'm attaching its datasheet

You can solder that resistor on top of the legs of the already mounted resistor ...

Do you mean that I solder directly a 33 ohm resistor on top of the other? In parallel right?

Stupid question mabey, but did You check the polarity ??

Polarity of what?
If you mean the lcd, theres no mistake, the pinout is the same, and i'm getting around 3.7v on the lcd legs corresponding to backlit. This lcd backlit was working with my previous board based on dmitris schema

15 + A
16 - K

[japi]

15 + A
16 - K

Yes, that polarity is ok