Repairing the focus of a Coronado PST H-Alpha solar telescope

Product Description
Focusing Repair of a Coronado PST H-Alpha Solar Telescope

The focusing mechanism on this PST was defective. The focus screw turned outward during focusing and didn't "transport" the prism. Focusing could then only be achieved by pushing it inward.

The problem was that a plastic ring had "jumped" over a cotter pin in the focus screw. Probably due to a material weakness. This prevented the spring from pushing the prism into the desired position or holding the screw in place.

We couldn't remove the cotter pin and replace it with a new one or screw because it was too tight and there wasn't enough space underneath. So we installed a hard paper gasket and a rubber gasket instead. To do this, we had to remove the prism to access the screw and install the gaskets on the screw. Now the PST can be focused again.

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