J&L Metrology Optical Comparator Technical Tips

Service Tips:

We have had much discussion as of late regarding the testing and verifying of mercury arc bulbs. We have complied this procedure to check the run circuit to verify its operation.

A qualified Service Rep or Electrician should perform this operation

• Remove the Lamp house and Mercury arc bulb.

• Put the red lead on the center post and ground on the outer rim of the lamp socket.

• Activate the lamp house safety switch "depress the micro switch"

• Voltage reading should read between 70 to 85 volts DC

• Activate start button

• Voltage should rise to between 400 and 480 volts DC

If you have performed this operation and confirmed voltages and your mercury arc bulb does not start or stay lit is safe to say that your bulb is bad. If either of the voltages are out of spec you have a run circuit electrical problem.

Anytime a mercury arc lamp is replaced use a volt meter and a DC amp meter and connect as shown in the original electrical schematics. Adjust R-17 for 250 watts, +/- 2 watts. This will insure the best performance and life from the lamp. This is also a good time to make sure the mercury arc power supply is clean and the fan is in good working order.

Periodically check light levels for your edge sensing. Make sure all the optics are clean, lamps are properly aligned and verify light levels. Even though the bulb maybe lit it may not be putting out the lumens that it did win it was new, If your lumens are weak it maybe a good time to go thru and check, alignment and replace the optical comparator bulb.

Don't use the vertical travel in the same limited area of travel. Supplemental bases and blocks should be used periodically to move to a different area of the vertical travel on the optical comparator. This will also prolong the life of the spindles or slides and rails.

Older machines which require moving of the mirror for each magnification can be upgraded to a fixed focal length lenses at the factory. This will provide less chance for magnification and or distortion errors, and provide a better quality image on the optical comparator.

If you check angles by rotating the screen remember the glass can slip inside the ring. You should periodically check the alignment of the glass centerline against the travel of the table. Reset the horizontal as required. While digital angle readouts are easier and faster to read they are not generally as accurate and repeatable as a mechanical vernier.

Wipe spindles and focus rods clean (front and rear) every (30 days) Apply a few drops of lubricating oil "Mobil Vactra #2". If there is a lower oil cup there is also an upper cup. Check and add oil to both every (30 days). Newer slide machines only require periodic greasing.  This should be done periodically by a factory certified technician. i.e. preventive maintenance and calibration inspections should be a part of your optical comparator.

DO NOT use solvents i.e. Windex or other glass cleaners as this will remove those precious little lines that we all need so very much. The manufacture has recommended "ivory bar" Hand soap lathered on hands and gently rubbed on glass chart and wiped off with a terry cloth or cotton towel, "no red shop rags" and rinsed with just plain old tap water.

One more important item to note Super Coat should never ever be used on glass charts, super coat is used for cleaning mirrors and lens only.