What causes the laser printer to print all pages with a washed out background?

Question

I'm trying to post a barcode scan content into mysql database. I don't understand my error, when I send there is no error displayed but still it does not post. Initially displayed the php script but now shows no action.Here's the code. I'm really stuck here.The activity below is XyzActivity.java and the post1.php then the activity_xyz.xml.

 XyzActivity.java

package com.example.boss.classattendance;

import android.app.ProgressDialog;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
import com.android.volley.RequestQueue;
import com.android.volley.Request;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.StringRequest;
import com.google.zxing.integration.android.IntentIntegrator;
import java.util.HashMap;
import java.util.Map;
import com.android.volley.toolbox.Volley;


public class XyzActivity extends AppCompatActivity implements 
View.OnClickListener{


//private static final String TAG = "AbcActivity";
public static final String KEY_FORMAT = "scanFormat";
public static final String KEY_CONTENT = "scanContent";
private static final String URL_FOR_REGISTRATION = 
"http://m.y.i.p/test/post1.php";
ProgressDialog progressDialog;

private TextView greetingTextView;
private Button scanBtn,post,Logout;
private TextView scan_format, scan_content;
String scanContent;
String scanFormat;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_xyz);

    progressDialog = new ProgressDialog(this);
    progressDialog.setCancelable(false);

    Bundle bundle = getIntent().getExtras();
    String user = bundle.getString("username");
    greetingTextView = (TextView) findViewById(R.id.greeting_text_view);
    greetingTextView.setText("Hello "+ user);
    scanBtn = (Button)findViewById(R.id.scan_button);
    scan_format = (TextView)findViewById(R.id.scan_format);
    Logout=(Button)findViewById(R.id.logout_button);
    scan_content = (TextView)findViewById(R.id.scan_content);
    post=(Button)findViewById(R.id.post_button);
    scanBtn.setOnClickListener(this);


    post.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            submitForm();
        }
    });
    Logout.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {

            Intent i = new 
  Intent(getApplicationContext(),MainActivity.class);
            startActivity(i);
        }
    });
  }

  public void onClick(View v){
    if(v.getId()==R.id.scan_button){
        com.google.zxing.integration.android.IntentIntegrator scanIntegrator 
  = new com.google.zxing.integration.android.IntentIntegrator(this);
        scanIntegrator.initiateScan();
    }}

   public void onActivityResult(int requestCode, int resultCode, Intent 
   intent) {
    com.google.zxing.integration.android.IntentResult scanningResult = 
   IntentIntegrator.parseActivityResult(requestCode, resultCode, intent);
    if (scanningResult != null) {
         scanContent = scanningResult.getContents();
         scanFormat = scanningResult.getFormatName();

        scan_format.setText("FORMAT: " + scanFormat);
        scan_content.setText("CONTENT: " + scanContent);
    }
    else{
        Toast toast = Toast.makeText(getApplicationContext(),
                "No scan data received!", Toast.LENGTH_SHORT);
        toast.show();
    }
   }
     private void submitForm(){
    final String scanContent = scan_content.getText().toString().trim();
    final String scanFormat = scan_format.getText().toString().trim();


    StringRequest stringRequest = new StringRequest(Request.Method.POST, 
    URL_FOR_REGISTRATION,
            new Response.Listener<String>() {
                @Override
                public void onResponse(String response) {

    Toast.makeText(XyzActivity.this,response,Toast.LENGTH_LONG).show();
                }
            },
            new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {



 Toast.makeText(XyzActivity.this,error.toString(),Toast.LENGTH_LONG).show();
                }
            }){
        @Override
        protected Map<String,String> getParams(){
            Map<String,String> params = new HashMap<String, String>();
            params.put(KEY_CONTENT,scanContent);
            params.put(KEY_FORMAT,scanFormat);

            return params;
        }

    };

    RequestQueue requestQueue = Volley.newRequestQueue(this);
    requestQueue.add(stringRequest);
  }


   }









   post1.php

   <?php

   require_once 'android_login_connect.php';
   $db = new android_login_connect();


    $response = array("error" => FALSE);

    if (isset($_POST['content']) && isset($_POST['format'])) {


     $content = $_POST['content'];
     $format = $_POST['format'];

     $sql = "INSERT INTO post (content,format)
     VALUES ('$KEY_CONTENT','$KEY_FORMAT')";

    if(mysqli_query($con,$sql)){
      echo ‘success’;
    } else {

        $response["error"] = TRUE;
        $response["error_msg"] = "Unknown error occurred in registration!";
        echo json_encode($response);
    }
   };
   ?>





  activity_xyz.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:fillViewport="true"
android:gravity="center"
android:orientation="vertical"
android:paddingLeft="20dp"
android:paddingRight="20dp"
android:scrollbars="vertical"
android:weightSum="1">

<TextView
    android:id="@+id/greeting_text_view"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginTop="30dp"
    android:text="Hello, User"
    android:textColor="@android:color/black"
    android:textSize="30dp"
    android:textStyle="bold"
    android:layout_weight="0.09" />

<Button

    android:id="@+id/scan_button"
    android:layout_width="match_parent"
    android:layout_height="30dp"
    android:layout_centerHorizontal="true"
    android:layout_centerVertical="true"
    android:layout_marginTop="40dp"
    android:background="@color/login_button_background"
    android:text="SCAN"
    android:textColor="@android:color/black"
    android:textStyle="bold" />

<TextView
    android:id="@+id/scan_format"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_marginTop="40dp"
    android:layout_weight="0.09"
    android:text="Format"
    android:textColor="@android:color/black"
    android:textSize="20dp"
    android:textStyle="bold" />

<TextView
    android:id="@+id/scan_content"
    android:layout_width="match_parent"
    android:layout_height="23dp"
    android:layout_marginTop="40dp"
    android:text="Content"
    android:textColor="@android:color/black"
    android:textSize="20dp"
    android:textStyle="bold" />

<Button

    android:id="@+id/post_button"
    android:layout_width="match_parent"
    android:layout_height="30dp"
    android:layout_centerHorizontal="true"
    android:layout_centerVertical="true"
    android:layout_marginTop="40dp"
    android:background="@color/login_button_background"
    android:text="POST"
    android:textColor="@android:color/black"
    android:textStyle="bold" />

<Button
    android:id="@+id/logout_button"
    android:layout_width="match_parent"
    android:layout_height="30dp"
    android:layout_marginTop="40dp"
    android:background="@color/login_button_background"
    android:text="Sign Out!!"
    android:textColor="@android:color/black"
    android:textStyle="bold" />



     </LinearLayout>

Solution 1

This answer is almost 7 years too late, but I believe it may be the definitive answer to the washed-out prints on the LaserJet 1200/1300 printers.

I recently spent several months trying to find the cause of this problem on my LaserJet 1300 (nearly identical to your LaserJet 1200). I too, had been using an off-brand toner cartridge (Cartridge World), and at some point it stopped being recognized by the printer. After replacing the cartridge, I had prints, but they were faded so much that the pages could almost be mistaken for blank.

I tried everything mentioned in the other comments and answers, and spent hours combing the internet for information on this problem. I cleaned every accessible part, including the corona wires, and replaced the toner cartridge with a brand new HP cartridge. I even took the laser off and cleaned the mirror (unnecessary). Some references online mention that the photo-sensitive roller in the cartridge can go bad on the shelf (it didn't, I tried a second brand new HP toner cartridge with the same result).

Finally, I disassembled the entire printer piece by piece because I was determined to save it (after 16 years without a single problem, I had some loyalty to this thing).

In my case, the problem was a faulty zEngine Controller Board - it destroyed a toner cartridge in the process (or perhaps the cartridge itself developed a fault that shorted out the board). I replaced the controller board with a used one from eBay for about $19. As soon I removed the original board, I could see a row of resistors with burn marks (R540-R544 next to the large capacitor).

The zEngine Controller Board is accessible from the back of the printer:

The area of the fault on the board:

A closer look at the blown resistors:

And here are the test pages after replacing the board:

Replacing the board was pretty easy, but I wouldn't call it trivial. It took about three hours even with YouTube videos showing the entire process (this video about removing the fuser will get you most of the way there). The good news is that it only took patience and a couple of decent Phillips screwdrivers (two sizes).

In retrospect, the source of the fault may well have been the toner cartridge, because both that and the board needed to be replaced in order get a functioning printer again. Additionally, the off-brand toner replacement leaked toner into some hard-to-clean areas in the printer. From now on, I'm spending the extra money on the HP cartridges.

Solution 2

To understand this better, you may want to read about how laser printing works.

A gray cast indicates that the drum is not getting or holding a sufficiently strong charge to hold the toner. It looks like either the OPC drum or the corona wire/primary charge roller is not working correctly. Try replacing the cartridge (the drum is part of the cartridge in many HP laser printers, including yours). If this does not work, the printer needs to be serviced.

Comments

[Michael Hampton]

Are you trying to print a page with a non-white background?

[WilliamKF]

No, this is happening for black text on white background.

[bwDraco]

Hmm... the controller board looks more like a power supply to me, based on the "primary"/"secondary" silkscreens on the PCB and the large power transistor next to the resistors you mentioned. I'm more curious if the problem was in fact caused by that transistor overheating? Power supplies can and do fail in destructive ways, especially given the high temperatures inside a laser printer...

[bwDraco]

Also, that board generates high voltages. The high-voltage power supply board is a common point of failure for laser printers. Use extreme caution when handling that board; it is an electrocution hazard.

[vallismortis]

@bwDraco Yes, this board is also the power supply, although it has only a single large capacitor. I had thoughts of testing the components in that area of the board, but once I had a working printer I decided to quit while I was ahead. None of the capacitors showed signs of leakage or bulging, and the only signs of damage were the scorch marks around those resistors.

[Forward Ed]

I am having a similar issue with an HP Laserjet 8150 DN. I was thinking it was a drum issue, but after reading this I have another culprit to potentially look at.