Inspection Of Lens Operations; Check Items; How To Treat After Inspection - Nikon ED 17-55mm f/2.8G IF Repair Manual

INSPECTION OF LENS OPERATIONS

Check the lens operations by using a personal computer after assembling.
○Check by using a personal computer
● Check items
1. Operation of MR encoder
・Drive the scanning of lens and check the difference in pulses between start end.
・In case the MR head of the MR encoder is malpositioned on the magnetic tape, the difference in pulses gets
large.
2. Lens-servo stop accuracy
・Check the number of overrun/underrun pulses (deviation of the stop position from the target position) per the
specified lens driving.
・In case the irregularity of mechanical operations does not take place in the focus ring driving unit, the underrun
tends to occur if it is heavy in the cam ring rotation of the MR encoder, while the overrun tends to occur if it is
light in its rotation of the MR encoder.
3. Lens-servo time
・Check the servo time (from starting and stopping the servo) when driving the specified lens by using the
oscilloscope.
・In case the irregularity of mechanical operations does not take place in the focus ring driving unit, the servo-
time tends to be long if it is heavy in the cam ring rotation of the MR encoder, while the servo-time tends to be
short if it is light in its rotation of the MR encoder.
4. Check of switches and lenses
・Check the ON/OFF operations of switches, the distance encoder and zoom encoder.
● How to treat after inspection
1. When the MR encoder operation is out of the standard:
Adjust the MR duty again. (ref. Page L46.)
If the pulse is out of standard, adjust the output pulse/waveform from the MR encoder again. (ref. Page L20.)
If the pulse meets the standard, replace the cam ring unit.
2. When the lens-servo stop accuracy is out of the standard:
Check the output pulse/waveform from the MR encoder. If it is normal, replace the cam ring unit.
3. When the lens-servo time is out of the standard:
Adjust the driving frequency and motor control again.
If the lens-servo time is still out of the standard after the readjustment, replace the cam ring unit.
4. When switches do not operate properly:
Check the wiring pattern of such troubled switch or replace it.
- L48 ･ AF-S DX17-55/2.8G -
INC
JAA78851-R.3617.A