20x2 LCD showing black first line

Hello,
please excuse me if I post in the wrong forum.
I have been searching and seen that this one is the most documented and people are willing to help.
Your experience in working with LCD panels is very important.
Thank you in advance for any lead that may solve the problem.

First of all I am new to electronics and only know the basic stuff.

I recently bought a old second hand METRON ACCUSONIC SSTIM device for medical learning.
I am Kinesitherapy student and only afford a broken one.
The functionality of the device is tested and all works
except:

Problem:
The LCD panel 20x2 WH2002M-TGH-JT shows only the first line blackened.

What I did untill now:

-Searched the net
-Resoldered the 16 connections
-Checked the voltages for the LCD (pin 1,2) and backlight (15,16) -4.99v
-Adjusted the contrast with the potentiometer -ok
-Grounded the R/W pin 5
-Opened the display and cleaned the ruber band
-All this time prayed for it to work

I have no programming skills and no way to do the rewrite of the program.

My questios are:

  • Could it still be the LCD that is broken and should I invest in a new one?
  • It is possible that the problem is from software?

Thank you again for your time and any pointers.

IMG_20180407_084012.png

I assume that your LCD has 16 pins.

Please, build connections between your LCD panel and Arduino UNO as per following diagram. This is a tested connection. (Mine LCD is 16x2).

Now, execute the following code. The message Hello! should appear on the 1st line beginning at DP0 position.

#include <LiquidCrystal.h>
LiquidCrystal lcd(8, 9, 10, 11, 12, 13); //RS, E D4, D5, D6, D7

void setup() 
{
  lcd.begin(20, 2);     //2 line; each line can show 20 characters
  lcd.setCursor(0, 0); //cursor is at 1st charcater of Top Line
  lcd.print("Hello!");  //shows : Hello!
}

void loop() 
{
  
}

Thank you GolamMostafa for the quick reply.

As I stated in the post have no ability now to test the LCD. I have a friend that is into arduino but can”t reach him right now. I will.

Can I deduce from your answer that it is at least 50% that the LCD is broken?

Can I deduce from your answer that it is at least 50% that the LCD is broken?

The following picture of you post indicates that the LCD panel itself is apparently good?

Before you declare that the LCD is bad, please execute the program of my post.

Before you declare that the LCD is bad, please execute the program of my post.

Are you sure about that? Your constructor doesn't seem to match the connections in your diagram.

Don

Thanks+ @floresta for meticulous observation that has detected mistakes in the wiring diagram. I have edited the post.