Replacing the Pressure Tuner O-Rings

Categories: Resource Library

One of the maintenance issues you may experience with your Lunt solar telescope is a change to where you screw down your presser tuner knob. 

The pressure tuner consist of a knob with a piston underneath.  On the piston are two rubber o-rings. Over time, in some locations, the o-rings will harden and allow air to leak past. You may find that the image can be tuned in but slowly fades or detail just can’t be attained.

This video walks you through the process of replacing the o-rings to restore your pressure to factory specification.

Replacing the Pressure Tuner O-Rings

Hi, I’m Faye Roman your Lunt Customer Service representative. I wanted to talk today about o ring replacement today. If you’ve had your Lunt solar telescope for a while and noticed that you have to tune in further to get to the right detail, you may need to replace your o rings. This is a common issue, and it is a rubber o ring so you can expect it to wear out over time. The good thing is the replacement is quite easy.


To replace the o rings, simply take off your pressure tuning knob. Place it on a table. That will give you the best work surface. Now you want to unscrew the cap that holds in the pressure tuning piston. Once you remove the cap, you’ll reveal the screw holding in the piston. Using a 2.5 mm hex, go ahead and remove the screw. Set that aside safely. Now once you have that screw taken off it will release the piston where the o rings live.


At this point, you will have received an o ring kit from Lunt Solar with two o rings and our factory grease. You’ll simply remove the wore out o rings and replace them with the new ones. For the grease, you’ll want to put a small amount of the edge of the o rings prior to installing. Once you have this all in place, you’re welcome to put it all back together.

So you’ll start with your knob here. Your hex screw. Go ahead and secure that into place. Then you’ll add on your cap again. Now your pressure tuner knob is ready to install on your telescope. Once you’re reinstalling it in your telescope, you’ll want to do a small counterspin. That will allow the treads to engage a little easier for you.


Once you have your o rings replaced, you’ll expect to have your scope back to where it used to being as far as your tuning range and the detail your seeing. If you think this might be an issue with your telescope contact customer service. If you need help once you’re installing, simply give us a call. We’re always happy to help.