megadrum and midi port: no sound!

[dmitri]

they all have been soldered (sorry for my english) and checked with a tester

Thinking logically, if the LCD worked before you soldered the jacks and stopped working after, than you either soldered them (one or several of them) incorrectly or you made a short or a break on the board while soldering. Disconnect(de-solder) the jacks and see if it returns the LCD to normality.

[lidel]

it's the only choice i have. so i thank you everybody for helping me and i'll write the origin of this problem once fixed.

[lidel]

this is the problem. sorry for the picture. as you can see the lcd doesn't show nothing. what can be the reason?

[dmitri]

I'm afraid I can only repeat what I said before: you need to find shorts/breaks/loose solder points.
Do you connect MegaDrum over USB?
Does Windows recognise MegaDrum?
Do you have a multimeter?

[lidel]

megadrum is connected by usb. windows detects megadrum, i don't have a multimeter

[dmitri]

megadrum is connected by usb. windows detects megadrum, i don't have a multimeter

Then it is Atmega/LCD pair not working properly. With the multimeter search for shorts/breaks around Atmega, LCD connector.

[lidel]

so you say it's only a cable not good connected or not soldered

[dmitri]

so you say it's only a cable not good connected or not soldered

I'm saying that you may have shorts/breaks on the LCD itself, in the LCD cable or on the board around the LCD connector or Atmega.

[lidel]

the lcd screen could be broken? sorry but i don't understand when you write "short" what you wanna say

[dmitri]

the lcd screen could be broken? sorry but i don't understand when you write "short" what you wanna say

It may but very unlikely since you said it was working and you didn't make anything which could damaged it, e.g plugging it in reverse, excessive soldering and etc.
A "short" is an electrical connection between contacts/wires/copper tracks where there shouldn't be.
A "break" is when an electrical connection is broken between two points where there should be.