Inspection Of Lens Operations; Lens Drive Stop Accuracy; Mr Encoder Operations; Lens Driving Time - Nikon AF-S VR Zoom-Nikkor ED 70-200mm f/2.8G IF Repair Manual

Inspection of Lens operations

Check the lens operations by using PC after assembling.
○ Check by PC
● Inspection item
1. MR encoder operations
・Activate the scanning drive of lens and check the difference in pulse no. when beginning and ending
inspection.
・In case the MR head of the MR encoder and the magnetic tape are misaligned, the difference becomes
larger.
2. Lens drive stop accuracy
・Check the number of overrun/underrun pulses (deviation of the stop position from the target position) per
the specified lens drive amount.
・If there is no variation in mechanical operations of the focus ring driving section, the underrun tends to
occur when the cam ring rotation of the MR encoder is heavy, while the overrun tends to occur when the
cam ring rotation is light.
3. Lens driving time
・Check the driving time (from starting and stopping the driving) of the specified lens by using the
oscilloscope.
・If there is no variation in mechanical operations of the focus ring driving section, the driving time tends
to be longer when the cam ring rotation of the MR encoder is heavy, while the driving time tends to be
shorter when the cam ring rotation is light.
4. Switches and lenses
・Check the ON/OFF operations of switches and the operating condition of the focus encoder and zoom
encoder.
●After inspections
1. When the MR encoder operations are not up to the standard:
Make the readjustment of the electrical device. (ref. Page L56-4
In case the pulse is not up to the standard, readjust the output waveform of the MR encoder.
(ref. Page L20)
In case the pulse meets the standard, replace the cam ring unit.
2. When the lens-servo stop accuracy is not up to the standard:
Check the output waveform of the MR encoder. If it is normal, replace the cam ring unit.
3. When the lens driving time is not up to the standard:
Readjust the driving frequency and motor control.
In case the lens driving time is not up to the standard even after the readjustment, replace the cam ring
unit.
4. When switches do not work properly:
Check the wiring state of the troubled switch or replace it.
Added page
ref. Page L56-4 ～ L56-6）
- L56-16 AF-S VR 70-200/2.8G IF -
INC
JAA78151-R.3584.A
May 17 2007