Am I Missing Something

[Amelia]

hi there, i have just decided to treat myself to a tmc v2 refractometer. The problem is i cant seem to calibrate it and am wondering if i am missing something completely obvious I follow the instructions to a t but still cannot get it. i remove the black cap to get to the calibration screw then and 2-3 drops of water on to the prism making sure it is evenly spread and no bubbles in it. I wait for 30 seconds then aiming into bright natural light i look through while adjusting the eye piece so i can see the scale. This part has been fine but then it says adjust the screw until the dark boundary coincides with the zero lines. The problem is there is no dark boundary! I have tried various times with different light, water and temperature but still no dark boundary. I have got some of my friends to look through thinking i am losing my eyesight but they cant see it either. Any help would be gratetfully appreciated as i am so frustrated and hope i am not completely stupid

 

[BigC]

Stating the obvious here. Place around 3-5 drops RO water on the prism and close the flap.
The whole screen should look a blue colour when you look through the eyepiece make sure you have turned the screw so as the bottom of the blue screen is aligned with the zero at the bottom. Rinse and dry, then try the same proceedure this time using your saltwater mix.
Regards
BigC

 

[andywg]

Also, don't bother calibrating with RO water, make or buy a known salinity solution of 35ppt and calibrate to that. Most cheap refractometers (ones we use) are not all that great at getting 35ppt when calibrated to 0ppt

 

[cynos]

should look like this when you look through

when you look through with normal water on it with the flap closed, turn the screw to set at zero

 

[Amelia]

thanks for all your help. I forgot to say in my post that i knew you had to close the flap. I am blonde but not that stupid Thanks for the reply anyway. I have tried everything you said but still not working. The picture cynos posted is what i kind of thought it should look like but cannot seem to get it. I will mess about with it later again and see if i can get. I use a hydrometer at the moment but have heard these are not as accurate. I will let you know how i get on. Cheers again your help is always appreciated!!!!!

 

[kj23502]

Maybe yours is broken? Can you take it back to where you got it and have them look at it?

 

[SkiFletch]

Yeah, it's very possible it's DOA. If you bought it online, perhaps taking it to an LFS to see if they can get it to work? Having the experience, I'm sure a decent saltwater employee could tell you if the unit is functioning or broken