What to look for and how to replace the drive gear
The Venerable Nikon Ti-E remains in service in research labs all over the world. One of the first autofocus-enabled instruments deployed with the integrated PFS, there isn’t much to ask for when it comes to a modern compound fluorescent stand. For owners of the instruments, it’s important to be aware of a big maintenance item on the scope – it’s motorized epi filter cube turret.
These turrets use a stepper motor to rotate the large carousel into various positions. The motor, control electronics, and positional sensing system are all high quality and should last many years, however, there is an internal gear which connects the belt drive to the carousel, and over time and stress of use, these gear rings have a tendency to crack.
I recently had a colleague ask if we could reverse engineer a solution for these, as Nikon charges a mint for them and in some cases they may be difficult to obtain depending on your region. You can see from the one supplied to me indeed had cracked, and under inspection, stress cracks from aged plastic are apparent.
It’s important to note here that these might “work fine” under manual rotation (where the motor isn’t applying stress to the belt drive). If you are having problems where the filter isn’t moving to position, or hearing any snapping, clicking or other unusual noises, it’s highly recommended to remove the carriage assembly, and to inspect the gear closely for cracks. This is a ~ 15 minute procedure and only requires a flashlight and removal of the top cover of the carriage.
If yours is cracked, we can supply a replacement within 1 day of order placement from our web store.
Here is a video of how to inspect and replace the ring as well.