henryp
I don't have that white spacer between the encoder pulley and the steel shaft.
I do't know what you mean about the coupling but mine looks like picture 2.
SC
If inexplicable PF encoder errors occur on a VJ-16xx printer, there is a modification available to make the printer less sensitive to this problem.
The modification consists of the placing of an extra ring into the pulley.
By placing this ring, you avoid a situation where the pulley can get deformed when tightening the screws.
Tools necessary
Torque screwdriver
Pulley retainer (part number: DF-49456)
crosshead screwdriver
Procedure to install:
Loosen the two screws holding the pulley.
Install the pulley retainer ring. Make sure that the grooves in the ring slide into the correct place.
Push the ring as far as possible into the pulley.
Fasten the two screws alternating until you feel some resistance.
Set the torque screwdriver at 7.5kgf/cm.
Fix alternating the two screws to 7.5 ±1.5 kgf/cm.
Power ON the printer and load media.
Feed the media a couple of meters forward and backwards by the jog keys on the keyboard. This to verify there are no errors and the printer does not make any strange noises.
In case there are strange noises or errors occurring, reposition the pulley.
In case noises or errors keep occurring you need to install a new pulley and / or encoder disc.
The spacer ensures that the pulley remains straight and true when the screws are tightened, without the spacer, the pulley could veer towards one side or the other when the 2 screws are tightened with unequal force.
VERY IMPORTANT !!!
When tightening the screws, make sure that the encoder disc is always lightly touching the right hand side guide pin of the encoder sensor as it rotates. (This is the guide pin near the printer mechanism). In case the disc is positioned towards the left hand guide pin, you need to reposition the pulley.
Please note: This disc alignment should be checked and performed if required even on printers without the pulley retainer.
The coupling on picture 2 is a rigid type. If the 2 shafts are not aligned, you can have a tight spot when the grit roller rotates because the axis of rotation can vary. Imagine rolling a straight tube on a flat surface, then imagine rolling a bent one on the same surface, this is the same effect when straight or bent grit roller rotates on the bearings when feeding your media. Picture 3 is a flexible coupling, on this type, alignment of the shafts is not as critical because the joint is flexible and can compensate for a slight change in the axis of rotation.