Some Common Problems with the UDY Colorimeter

The most common failure with these units is the L.E.D.

If you can not get a good zero: Set these Conditions: Water in the Cuvette Gain pot in the center of it's range Zero pot FCW (clockwise) Mode selector in CAL Under these conditions one should see a negative number (> -0.030) on the display. If zero (0.00) can not be achieved by adjusting the zero pot the problem is most likely a failing L.E.D. "Not enough blue". The internal regulator monitors the amount of light produced by the led and adjusts the current to maintain a set amount. The L.E.D. is not magical but, it is specific to our unit I.E. 30 deg angle, 470 nm wave length, 1500 mc (light intensity ) etc. You can purchase a new L.E.D and holder from UDY Corporation.

Another measurement you can make

Test for Blue Signal

Set Conditions:

• Water in Cuvette
• Gain pot (N/A)
• Zero pot about 3/4 of the way to stop ( where you would usually find Zero.)
• Mode selector in the Signal position.

When the L.E.D is producing enough blue light the display should read 2.48 - 2.50, this measurement is in Volts measured at what we call Vsig.   As concentration value goes up toward 1.320, Vsig voltage goes down which is the same as the L.E.D becoming dimmer. (That makes sence. For example:   If you applied full strength concentration and then tried to zero the unit - There would not be enough range.)   That's is what is happening here, except with water.

Going Deeper into the Blue

Remove the Front Panel

An addtional test is to remove the panel. Locate the lower left corner of the circuit board. there are two pins labeled LED1 and LED2. ( by the connector ) Measure the voltage across these pins to be .200 volts as stated in the L.E.D. replacement procedure. If the measured voltage is much higher it means that the L.E.D. regulator has adjusted the current beyond the L.E.D's limits and the L.E.D will need to be replaced.

Get A New L.E.D.

Install it yourself

On this site are instructions on how to change this led. You can purchase a replacement LED with holder from UDY Corporation web site. This site looks like it handles Mills and the like but, you can input the part number 30-0011A and add L.E.D.(s) to your cart. goto: https://alphapdworks.com/NewUdySite/CycloneSampleMill.php input in the search section the part number 30-0011a. When you receive your L.E.D. Follow instructions on this site for replacement.

If you don't care to do all of the above, simply send the unit to UDY corp for repair. UDY Corporation 201 Rome Court Fort Collins CO. 80524 or call 970 482 2060 for instructions. We will quote the repair cost before you incur any expense.

Normally we will replace the L.E.D and blue filters if necessary, recalibrate the unit and clean it up. We'll add update modifications when possible and test it to make sure it's functioning as it did when it was new.

The average cost for this maintenance procedure is approx. $300.00 to $500.00 depending on the condition of the unit.

I hope this was helpfull - good luck and thank you for working with UDY Corporation.