my old LCD 16x2, see only second line, strange characters

[tindim]

found in my nightstand two old disassembled lсd displays 16х2,
and decided to restore them,
the first display is classic 16x2 (blue background, white letters),
wiped everything with isopropyl alcohol, and cleaned,
took the pliers and squeez conductive rubber,
assembled the display,
but I see strange characters,
and don't see the first line, contrast worked, the cells are glowing,
when working in 4-bit mode, which pin is responsible for the first line?
thank's

//

#include <LiquidCrystal.h>  // 
LiquidCrystal lcd(7, 6, 5, 4, 3, 2); // (RS, E, DB4, DB5, DB6, DB7)

void setup(){ 
  lcd.begin(16, 2);                  // 

  lcd.setCursor(0, 0);              // 
  lcd.print("Hello, world!");       // 
  lcd.setCursor(0, 1);              //
  lcd.print("zelectro.cc");         // 
}

void loop(){
}

[PerryBebbington]

when working in 4-bit mode, which pin is responsible for the first line?

No pin is responsible for the 1st line. The 4 pins are for transferring data and instructions to the the display in 4 bit (half byte) chunks. You tell it where you want to display the data and you tell it what to display. If you are getting good data on one line but not the other then either your code is wrong or the display is faulty. Try a known good display, if that's OK it's not a problem with your code.

In your photos you appear to have it weird for 8 bit mode, you diagram shows 4 bit mode. Both should work though.

HD44780 Datasheet(PDF)

[LarryD]

[tindim]

:)))) no trash box, only hardcore
i worked for several hours,
and it turned out to solder the break of the contact lines,
surprisingly a lсd display with blue glass,
after bending the lower lid mountings,
display is working,
but I still have one more display with yellow glass,
as I understand it, I need to first check pins with arduino code on working display,
and then using the logic analyzer to check the result
with another pcb?
if the result is the same then and if it works,
need to solve the problem with contacts between the glass and the board,
maybe an electro contact spray ?
i not see a full grid of cells on the yellow display ?
thanks

[PerryBebbington]

Well done.

You remind me of my dad. After he died I inherited his circular saw. One day I put it down on the mains cable and cut the cable. I took the plug off the damaged cable to discover he'd repaired a broken screw terminal in the plug. Anyone else would have thrown the plug away and used a new one.