Dear All,
           I am trying to display my sensor's output voltage to the PM129B
31/2 Digit LED Digital Panel Meter.

The display information is available at the following link:

http://store.kysanelectronics.com/servlet/-strse-68458/PM129B/Detail

The data sheet of the display is available at this link:

http://www.circuitspecialists.com/images/PM-129A&Bspecs.pdf

The display uses a ICL7107 IC which has A/D conversion and display
utilities.
http://www.intersil.com/data/fn/fn3082.pdf

The problem I am facing is that I am not able to read the output voltage
using the display. The voltage uses a 5V power supply. I have set the
display's voltage range to be 0-20V.

When I switch on the power supply to the display, it shows that "0.00". So,
I concluded that the display is in good condition.

Now, when I tried giving a 12V to the analog input pins, to test the
display, it is displaying the character 1 and a dot. When I cut off the
signal voltage, I see that the value indicated is gradually reducing to
zero. I also noticed that it seems to decrease from some random higher
value. For example, while decreasing, it shows values like this 16.36, 12.00
and so on until it shows zero.

There is a variable resistor "105" available in the back side of the
display. I assumed it was meant for calibration of the display voltage and I
tried adjusting it. There were no changes and it was showing the same
character 1 when I provided the input voltage. In order to double check
this, I tried giving a signal using a 1.5V battery. It seems to show the
same character 1.

Is there a possibility that the calibration is wrong. I noticed an
information in the website saying that if needed, we must add proper voltage
dividers and decimal point wire jumper. I don't have an idea what they meant
by this information.

Any help in this regard, would be appreciated.

Thanks in advance.

Regards,
Sairam
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