Adjust the carriage position for light detector back and forth a few mm in 0.5mm steps. Remember to reset diodes every time.
Monitor the voltages while you perform calibration and see if you notice a sudden drop. If you notice a drop, start disconnecting the LDD's.
You said you replaced DDB and LD - were these new or known to be in working condition?
Logs may be very useful - check the timestamp in the error log then look in the general log to see what happened before it. You can PM me with the logs attached
Monitor the voltages while you perform calibration and see if you notice a sudden drop. If you notice a drop, start disconnecting the LDD's.
You said you replaced DDB and LD - were these new or known to be in working condition?
Logs may be very useful - check the timestamp in the error log then look in the general log to see what happened before it. You can PM me with the logs attached