Md problem (SOLVED). Lcd without message and midi activity

[Maylord.war]

I just finished my 2.5 pcb but i have problems

When i connect the usb port the backlight of lcd turns on but without any message. The led of midi activiti stay off and i don't know where is the problem.


The cap i use is .22 for 220Nf and .47 for the 470Nf.

At the moment i don't have the 18f2550. The atmega is 644 with the last bootloader .

Crystal 20 and 12 mHz

The pcb and the solder apparently are perfect but i don't know why don't work.

Can you suggest me the procedure to try to resolve the problem?

Thanks a lot

[dmitri]

Where are evidences of you reading "MegaDrum FAQ. Read it before posting in this forum!" and following "7. Having LCD problems? Read this topic." in particular?

[Maylord.war]

Hi dmitri

Thanks, I've see the FAQ.

The LCD not is defected, because in another 3.2 kit from synthex works perfectly.


The atmega is fully programmed.

I will post a pictures to show the boad.


I don't use the trimpot for contrast, i've putted 100nf and 10k resistor in parallel ( viewtopic.php?p=19252#p19252 ) and last 1k on 3-14 of lcd

I do not think it's just a problem of LCD because the MIDI activity by Led is absent.

Thanks

[dmitri]

I still don't see how you followed the instructions from the link, e.g. you didn't say a word about how you tested the contrast adjustment of the LCD even though the instruction says quite a lot about what you need to do to test it.

[Maylord.war]

Hi

I have checked the C9 R19 R21 and the value is correct. I've try to reverse the polarity of 15 and 16 pin of lcd.

I doubt the problem is from the Lcd connector because if i hit the piezo the led of midi activity stay off, the same atmega and lcd works perfectly in my 3.2 synthex kit.

[dmitri]

Hi

I have checked the C9 R19 R21 and the value is correct. I've try to reverse the polarity of 15 and 16 pin of lcd.

I doubt the problem is from the Lcd connector

Who says the problem is from the LCD connector?

because if i hit the piezo the led of midi activity stay off,

You can use the LED as a check provided you are sure it is working, connected properly, there are no problems with tracks on the board and wires leading to the LED and the piezo is connected to an input which is not disabled and also has no connectivity problems of its own.

the same atmega and lcd works perfectly in my 3.2 synthex kit.

I guess it says much about your board - it has a problem with soldering/components/tracks.

And again, you didn't show how you followed the instructions from the link provided. The fact that it's called "Having LCD problems?Read this first before asking questions" doesn't mean the problem is necessary with an LCD, it's just a visible manifestation of a problem somewhere and the instructions tell you how to track where it can be.

[Maylord.war]

Hi all

I've solved the problem with my board, there was a microscopic ball of solder near two small traces.

Now the MIDI activity and the LCD works perfectly without the pot.

Thanks Dmitri for the support.