How to Calibrate a 12V LCD Digital Voltmeter Panel Using CA3162 and CA3161 ICs

*Hello,*
Since I am a newbie here, I don't know if comments posted at specific EEWEB pages ever get responses, so I'm playing it safe by posting a copy of it here.
Thank you for your help -- and remember, I'm NOT an electrical engineer (it's the only 1-of-2 choices available when I registered here
N.B.: I attached a copy of the image mentioned and linked below in the correspondence to the company of this product since one can do so here. The front of the unit looks 99.99% identical to the one featured in the directly below linked page here at this site.
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*COMMENT POSTED ON FEB. 6 AT ELECCIRCUIT.COM:*
http://www.eleccircuit.com/the-cheap-digital-...3162-and-ca3161/comment-page-1/#comment-19627
*Hello,*
Below is a copy of what I sent to one company that makes this model (but to which I may or may not have any response). I'm not an electrical engineer, just a DIY guy who can read a motorcycle electrical diagram but am stumped on how to solve the problem I have.
Hopefully the below is self-explanatory and I hope you can give me some basics so that I can adjust the VR1 and VR2 to match what my Craftsman multi/voltimeter shows. At the time of the below provided photo of the back of this LCD panel, I had not seen the stamped "VR1" and "VR2" words next to the 2 respective adjusters.
I simply need to know what to do with each one respectively so that when the battery is topped off/full (about 13.10v) and when needing to be re-charged (about 12.65v or so) it is as accurate as a voltmeter.
Thank you for your help.
Kind regards,
~ Philip Knight
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*SENT TO DDHYB.COM about LCD panel guage on Feb. 6 2013*
*Hello,*
I purchased an LCD panel manufactured by you -- TY3150-DV. This is for use on a motorcycle to check the 12v battery and the usual range needed is from =/- 12.30v -> =/- 14.50v.
Perhaps one is for the high end voltage, the other for low end -- but I simply do not know for I have never used this kind of adjustment (the older LED type panel I have only had one screw that was at the top of a small plastic rectangle box on the circuit board).
Could you please send instruction on how to use these two screws to accurately calibrate this LCD panel?
Thank you.
Sincerely,
Philip S. Knight
Los Angeles, CA USA

Philip you have not told us if the TY3150 is accurate or not compared to you test meter.  If not accurate (which I assume is the case) what does it read at the voltages you need to measure?Usually DVM modules like this are reasonably accurately calibrated from factory.
I looked on the net but a quick search finds nothing.....Usually one adjustment would be for zero, the other for calibration, and they may have interdependence, but without a manual you'd be a bit in the dark.....Cheers// David