NATIONAL 405TBL (01) PDF Document

Stereoscopic microscopes such as the NATIONAL 405TBL are used for viewing 3 dimensional objects, inspection or assembly of small parts, and for dissection of biological specimen. They provide an upright, unreversed image which permits easy manipulation of the object being viewed while looking through the microscope. They are designed for viewing solid objects at low magnification, but they will also permit viewing of some transparent specimen slides.

The only difference is that the 400 series has a vertical viewing head (eyepieces are straight up and down) and the 405TBL series has a 45° inclined viewing head. The inclined viewing head permits more comfortable viewing angle when user is seated.

Microscope magnification is determined by multiplying the number on the eyepiece times the number on the objective lens. For example, a NATIONAL 405TBL with 10x eyepieces and 2x objectives provides 20x magnification.

Remove microscope stand and head assembly from carton. Remove rubber eyeshields, dustcover and warranty card. Remove “L hex wrench” (used to remove locking set screw on stage plates), and “pin spanner wrench” (used to adjust focusing tension).

Install rubber eyepiece shields over top of eyepieces with the flared portion of the shields positioned at the outside edge of eyepieces.

Retain the styrofoam container in case you need to transport, store, or return the microscope for service. If it becomes necessary to ship the microscope for any reason, pack it in the styrofoam container, and then pack the styrofoam in another corrugated shipping container for optimum protection. Use of the styrofoam alone will not provide adequate protection in transit, and will void your warranty.

The NATIONAL 405TBL model is illustrated as having both incidental (top) and transmitted (bottom) illumination.

Microscope models having both incidental (top) and transmitted (bottom) illumination are supplied with a frosted glass stage plate (80mm diameter) already mounted in the microscope base. They are also supplied with an accessory black/white contrast plate packed in the styrofoam container. 405 Series purchased after 1/1/10 will be supplied with contrast plates, one black and one white.

Three switches are on top of base: (1) main power on/off, (2) “I” switch controls incident (top) light, (3) “T” switch controls transmitted (bottom) light.

FROSTED GLASS PLATE MUST BE USED IF USING BOTTOM ILLUMINATION. HEAT GENERATED IN BASE FROM BOTTOM LIGHT WILL WARP OR DAMAGE THE PLASTIC BLACK/WHITE PLATE. SUCH DAMAGE WILL NOT BE COVERED BY WARRANTY. It is acceptable to leave the glass plate in place for most viewing purposes.

The black/white contrast plate can be used when viewing opaque objects or for dissecting. Choose side of plate providing best contrast with specimen. Remember, do not use bottom light with this plate in place.

This permits each user to adjust spacing between eyepieces in order to accommodate distance between their eyes. Observe that each eyepiece tube on each side of microscope head is mounted on its own gray metal housing. While looking through microscope, use both hands to firmly grasp gray metal housing and gently pull or push the sides in a horizontal path until images viewed through both eyepieces appear as one and field of view appears as one circle of light.

Place object or specimen slide in center of stage plate.

The viewing head is mounted on a post, and height of head can be adjusted up or down on post in order to focus on difference sized specimen. Loosen the post locking knob located on back of focus block so that viewing head can move freely up or down on post.

While looking through microscope, move head up or down on post until image is in approximate focus. Tighten post locking knob. It is not necessary to make this adjustment every time you change objects being viewed, unless there is a significant difference in thickness or height of objects.

Rotate focusing knobs with both hands until specimen comes into sharp focus in right side of microscope.

Because most people have some difference in vision between the left and right eye, your microscope is equipped with a diopter adjustment on the left eyepiece to compensate for this difference and assure that you will see one corrected image when looking through microscope.

Observe that the knurled diopter ring on the left eyepiece tube can be rotated to move the eyepiece up or down slightly. When a silver ring on the eyepiece tube is visible just below the diopter ring, the focus of both sides of microscope is matched for 20/20 vision.

If you do not have 20/20 vision, turn knurled diopter ring until left side of microscope is also in sharp focus. Left and right images should now blend into one focused image. The microscope is now adjusted for your vision, and no further adjustment of the diopter should be required. Only the focusing knobs will require further adjustment when viewing objects of different thickness.

Prior to cleaning any lens surface, brush dust or lint off lens surface using a camel hair brush. You can also use an ear syringe or canned compressed air, such as that sold by most computer stores.

To clean eyepiece lenses, do not remove from eyepiece tube. Clean only the outer lens surface. Breath on lens to dampen surface, then wipe with lens paper or tissue. Avoid wiping dry lens surface as lenses are scratched easily. If excessive dirt or grease gets on lens surface, a small amount of Windex can be used on a cotton swab or lens tissue. To clean objective lenses, do not remove objectives from microscope. Clean front lens element only, following same procedure.

The only mechanical adjustment you might ever require is the tension of the focusing mechanism. This has been adjusted at the factory, but over the course of time it may loosen and cause the head of the microscope to slip downward on the focusing block.

To adjust, observe that stem of focus knob on one side of microscope has a tension adjustment collar with four small holes. Only one of these holes contains a small set screw. Using a small jewelers screwdriver, loosen this set screw. Your microscope was supplied with a small pin spanner wrench having one prong. Insert pin of the wrench into one of the holes, turn collar clockwise to tighten tension, counter-clockwise to loosen tension. In the event you have misplaced the wrench, a large rubberband placed around the collar will permit you to grip the collar and turn it by hand in order to accomplish the same adjustment. After adjusting, tighten the small set screw to lock collar in place.

NOTE: It is recommended that you leave the tension as loose as possible for ease of focusing, yet not so loose that it permits the head of microscope to drift downward from its own weight and cause the microscope to “drift” out of focus.

Remove knurled lamp retaining screw, located on side of top lamp cover, and remove cover from lamp. Remove lamp from pressure clips by pulling straight out. Holding new lamp with tissue or cloth to avoid getting body oil on lamp, push into pressure clips. Replace lamp cover and secure with knurled lamp retaining screw.

Remove stage plate and observe lamp held in place by pressure clips in base. Carefully grasp bulb and remove from clips by pulling straight out. Holding new bulb with tissue or cloth to avoid getting body oil on lamp, push into pressure clips. Replace stage plate.

The fuse is located at rear left side of microscope base. To remove fuse from holder, insert a 6mm screwdriver blade into slot located in rear of fuse holder cap. Slightly depress and rotate screwdriver 1/2 turn in direction of arrow, release pressure on screwdriver to release the fuse. Pull cap and fuse out of fuse holder. Insert proper fuse into fuse cap. Insert fuse cap into fuse holder. Using screwdriver, rotate fuse cap assembly in opposite direction of arrow until guide slot engages, depress fuse cap and rotate 1/2 turn to lock into holder.

If the light fails to operate on the NATIONAL 405TBL models, the reason could be that the outlet is inoperative, the AC power cord is not connected, the lamp is burned out, or the fuse is blown. The solutions are: Have qualified service technician repair outlet, Plug into outlet, Replace lamp, or Replace fuse, respectively.

If the NATIONAL 405TBL is unable to focus, the reason could be that the Head of microscope drops from its own weight. The solution is to Adjust tension control. Another reason could be that the Objective lenses are dirty. The solution for that is to Clean objective lenses.

If the NATIONAL 405TBL has poor resolution (image not sharp), the reason could be that the Objective lenses are dirty or the Eyepiece lens is dirty. The solutions are to Clean objective lenses or Clean eyepiece lenses, respectively.

Spots in field of view on the NATIONAL 405TBL could be caused by dirty Eyepiece lenses. The solution is to Clean eyepiece lenses. Spots in field of view can also result from dirt on inside of eyepiece. It is recommended that you have service technician clean inside of lens.

The NATIONAL 405TBL is covered under the illumination chart for illuminated models. Assuming the NATIONAL 405TBL has 10X eyepieces (WF10X supplied) and 2X objectives, the total magnification would be 20X. For optional WF15X eyepieces, the total magnification would be 30X.

Magnification Chart (illuminated models)

If the NATIONAL 405TBL is a non-illuminated model with 2X objectives and 10X eyepieces, the total magnification is 20X.

Magnification Chart (non-illuminated models)

Determine whether the black or white side of the stage plate will provide best contrast with the specimen to be viewed. The white side will be used for most viewing. It will always be required when viewing transparent specimen slides because it better reflects light through specimen slide.

To reverse black/white plate, loosen locking set screw located at front of base with “L” hex wrench provided. Insert plate with selected surface facing up. Tighten locking set screw.

This model is furnished with two stage plates. The frosted glass plate is used when viewing transparent specimen slides or for viewing some specimen thin enough through which light can pass (insect wings, etc.). On this model, locking set screw is located on one side of base.