Dolev 800/800V/800V² - Assemblies
Dynamic Optics
Encoder

Description
Replacing the Encoder
Adjusting the Encoder and Checking the Signals

Description

The encoder head supplies the data pulses stream to the spinner indexer. It also supplies the start of live signals to the imagesetter. It is a part of the Spinner Assembly (509B34251).

The encoder is at the front of the the Dynamic Optics beneath the spinner
assembly cover. The Dynamic Optic is located on the carriage guide beam.

Replacing the Encoder

Before You Start
Tools & Accesssories
Disassembling the Encoder Head
Assembling the Encoder Head

Before You Start

1. Power off the imagesetter using the control panel ON/OFF switch.
   
   
2. Open the left and right service doors. Remove the light-proof covers.
   
   
3. The replacement requires good lighting. Set up a light stand or some other method of providing sufficient lighting.

Tools & Accesssories

Oscilloscope
Set of Allen keys
Phillips screwdriver

Disassembling the Encoder Head

(Cat. No. 313M20010)

1. The encoder cable passes through the encoder cover (#29). To remove the encoder cable, push it into the encoder cover.
   
   
2. Free the encoder cable from the plastic band.
   
   
3. To remove the encoder cover, release the screws (#28) on the side and pulling out the cover.
   
   
4. Disconnect the encoder cable connector from the encoder. Release the lower screw from the encoder base.
   
   
5. Release the two screws (#23) that hold the encoder to the motor base and gently pull the encoder (#24) to the side.

Assembling the Encoder Head

1. Insert the new encoder in place of the old one. Take special care that the head does not scratch the disk. Push it to the end of the movement.
   
   
2. Fasten the screws (#23) and tighten them well.
   
   
3. Check the distance between the encoder head and the encoder disk by inserting film. Insert a strip of film 4 mil thick. It should pass through the gap.
   
   
4. Try to manually rotate the encoder disk. It should move freely.
   
   
5. Re-connect the encoder connector.
   
   
6. Power on the imagesetter.

Adjusting the Encoder and Checking the Signals

Encoder Specifications
Instructions

Encoder Specifications

• index pulse amplitude    -600mV to -1.5V
  
  
• data pulse amplitude    1.5V PTP to 4V PTP
  
  
• must be 2000 data pulses between every two index pulses
  
  
• the depth of modulation must be less than 10%

Instructions

1. Check if the encoder disk is clean and if necessary clean with rice paper and alcohol.
   
   
2. Connect oscilloscope ch-1 to TB4 and ch-2 to TB5. The reference is leg 1 (GRD) close to the center.
   
   
3. Enter the Diagnostics program. Under the Motors function, select Spinner On.
   
   
4. Check the signal amplitude. It should be as in the following figure:
   
   Signal Amplitude
   
   
5. Next, check for good modulation depth.
   
   Modulation Depth 1
   Modulation Depth 2
   
   
6. The correct timing insures a rise of the DATA pulse (one for each index pulse) in the middle of an index pulse.
   
   If the rise of the DATA signal is too close to the leading edge or the falling edge of the INDEX pulse, the sample was taken in an unstable area. This causes JITTER on the film and error messages such as:
   
   MISSING EL-OP PULSES, WRONG ENCODER CLK.
   
   Index Pulse Relative to Data Pulse
   
   
7. If the signal is not in the correct position, loosen the screws and tilt it to a new positional.
   
   
8. The spinner should stand still and the tilt should be within the limitations of the holes.
   
   
9. Check for jitter after optimal signal adjustment and relative positioning. Synchronize the scope on the trailing edge of the index pulses and check that the trailing edge of the data pulses jitter no more than 100 nSec.
   
   If an acceptable signal is impossible, the spinner is defective. You must replace the carriage.
   
   
10. Put back the encoder cover.
    
    
11. Secure the cable on the harness.
    
    
12. Expose a CALPLOT (slashes).