Quake alarm sensor+ Arduino Uno

Hello
Im trying to make earthquake alarm project. So my first step is reading sensor data. As sensor I took this device quake alarm
I cut off the speaker from the detector, pass the wires through a voltage regulator and then connect it to an analog port in the Arduino board. Then I tested. As result I got this:
926
926
925
925
925
925
925
925
924
924
924
924
924
1023
1023
1023
1023 // and this 1023 was repeated even shaking is stopped
The problem is when occurred shaking analogread=1023 (If I understood its max analogread value like 5 V) and when shaking is stopped I still had 1023 . In peace time value <990.

void setup(){
Serial.begin(9600);
  
 
  Serial.println("Reading...");
  
  }

void loop(){
  int value;
  int detectorValue=0;
  detectorValue = analogRead(A1);
  value=detectorValue;
     
Serial.println(value);
delay(1000);
 
 }

can't you isolate the sensor in the appliance?

Can you post a picture of the inside & connections?

Unfortunately I cant, because the device has pendulum inside when pendulum moves it sends signal to speaker as output, there are only 2 wires red and black to speaker I guess red to analog pin and black is for gnd .Here the first photo http://i1372.photobucket.com/albums/ag360/Banu_Buribayeva/Mobile%20Uploads/image_zps77ee1699.jpg

http://i1372.photobucket.com/albums/ag360/Banu_Buribayeva/Mobile%20Uploads/image_zpsa0718b8f.jpg. Here the second photo

it does't show the inside of the white box ...

I cant open the box((((

pity...

I have only this manual

Maybe you have to use an oscilloscope to see if the signal you are acquiring is 0-5V. I believe that is not 0-5V.