Removing the upper belt assembly

Some sampling requirements are better served by single belt operation. Under some conditions, the upper belt pressure may damage samples, or the upper belt rocking idler may cause undesirable mechanical pressure. Removing the upper belt pulley, drive pulley, and rocking idler will provide a more obstruction-free path through the sensitive area. The fluorescent tube must remain in place so sample thickness is limited to 2.5 cm (increased from 2.0 cm with upper belt assembly intact).

Watch a video of this procedure at

  1. Disconnect the power.
  2. Remove the rear housing (see Rear housing removal).
  3. Loosen the transparent belts (see Transparent belt tension adjustment).
  4. Remove the fluorescent tube (see Fluorescent tube installation).
  5. Separate the fluorescent tube power cord connector located near the instrument front plate and under the belt drive pulleys. This connector may remain mated if the front plate can rest near the instrument without straining the cord (see Figure 4‑2).
  6. Remove the hexagonal socket screws (7 total) which are directly contacting the instrument plate (see Figure 2‑2). Other similar screws are visible on the front of the instrument which fasten the pulley support brackets (see Figure 4‑2). Do not loosen those screws.
  7. Slowly remove the front plate. Be certain that all pulleys and idlers remain in place, resting on the support brackets (see Figure 4‑2). This is accomplished by repeatedly pressing the pulleys and idlers back into their rear plate bearings.

Caution: Do not allow the upper belt rocking idler or the lower belt idler to drop onto the mirror located directly beneath these components.

  1. Remove the upper belt rocking idler.
  2. Remove the upper pulley.
  3. Remove the upper belt.
  4. Remove the upper drive pulley gear (see Figure 2‑3). A 7/64" (0.278 cm) hexagonal key is required for the socket set screw. This key is not provided with the instrument. Then remove the upper pulley.
  5. Replace the front plate, connect the fluorescent tube power connector and replace the fluorescent tube.