Product

• Lotem^® 200
• Lotem 200 Xpose

Component

laser diodes

Symptoms

Cause

The combination of the following:

• LDD bias current
• laser diode characteristics
• optical path
• plate sensitivity

Solution

First, check if there is a laser leak from the diodes:

1. Load a new Toray plate on the drum.
2. Apply laser group calibration.
3. Turn off all the diodes.
4. Operate the drum at the lowest possible speed: 1 rpm.
5. Move the carriage to position 500 and then back to HP.
6. Process the plate and examine it for spiral lines.
   Spiral lines indicate leakage from one or more diodes.

Note: After any mechanical change, repeat steps 1-6 to check if the problem is resolved.

Solution

To isolate the leaking diode or diodes, disconnect the LDD cables from half of the diodes and repeat steps 1-6. Repeat this step with different groups of diodes until the leaking diode is isolated.

Note: You can quickly determine how many diodes leak, (but not which diodes) with the following formula:

No. of leaking diodes = LineWidth(µ)/[1000/res(dpm)]

For example, if line width = 90µ and res = 100 dpm:
No. of leaking diodes = 90/[1000/100] = 9 diodes

• If one or more diodes, but not all diodes, leak:
1. Switch the LDD board from the leaking channel with an LDD board from a non-leaking channel.
2. Replace the LDD board.
3. Replace the specific diode.
• If all diodes leak, it indicates a high standby bias applied to the diodes. In this case, escalate the problem according to the instructions on the Escalation page.

Technical contact(s)

Mario Amir

Submitted by

Mario Amir

Date submitted

02 Sep 2003