Lunt LS50THa PT deassembly- the saga continues lol

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T McVicar
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Lunt LS50THa PT deassembly- the saga continues lol

Post by T McVicar »

Okay, just giving a recap and an update here. I bought a preowned lunt 50mm. It was a 2014 model sold in 2015 and barely used.

I went out with it earlier and had trouble with it. From the next experience out, I realized my solar finder was off. That's fine. I could find and focus the sun loosely with the helical focuser without the solar finder, great, this means no decontacted elatons. That's even better. I still had the hunch that I had an issue with the pressure tuner as well, I was correct.

I opened it up, found that it was missing an O ring. I saw one red o ring on it, on the inside groove on the plunger, rather than the outside tip.


I contacted Lunt about my scenario, they said the first step of my problem is to send me o rings and grease w/ instructions. My scope was under warranty, and they sent it to me for free with instructions. This service alone makes me want to deal with Lunt for future products. I was very happy.

Alas, my woes continue though. They sent me two black o rings with the same diameter. I took off my red ring, it looked to be like the same size as the black ones.I put a gratuitous amount of grease they supplied and the two black o rings and assembled the pressure tuner. It wouldn't fit on! I fought with it for a while, trying gently at first. Then trying different ways to push it down while simultaneously screwing it back on. I removed excess grease, and still nothing. It was too big to thread now.

It simply wouldnt fit and after getting slightly frustrated and running out of ideas, I stupidly tried to lightly force it on with a rubber mallet to get the o ring inside the brass opening so I could screw it on with the thread. In my attempts, I marred and damaged the inside threads of the PT! I should have known!!!!!! Le sigh.

At least the brass part of the scope looks fine. I looked more closely at the picture they supplied. It showed a grey o ring on the inside diameter and the red ring actually on the outside groove, on the tip part. With nothing to lose, I switched one of the new black o rings out with the old red one- the one on the tip of the plunger of the PT. It now fits in comfortably about half way inside the brass tube, which would be about the max distance from a fully compressed PT when threaded I think.

Had I would have known that there were two different sizes, and the red one NEEDED to be on the tip, I wouldn't have any issues compressing it in enough to thread it. UGH. I didnt see a noticeable size difference visually

Now tomorrow, I get to reach out to Lunt and see if my O ring dilemma was accurate with two different sizes, color coded or something. And also to see if and how much is a brand new PT part will cost me.

Yay(!)


Not sure if my PT is salvageable be rethreading or cleaning them up somehow. It looks like they need to be machined again to be honest. Even with the plunger removed, the PT will simply not screw back on the lunt and I dont want to fight and possibly damage the brass male end as well.

To be continued...
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Lunt LS50THa
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Re: Lunt LS50THa PT deassembly- the saga continues lol

Post by T McVicar »

The images start from the bottom up. The image with the red ring was the before shot. With only one ring on the plunger. The new black ring goes on that spot with the red ring on the first groove (the tip of the plunger) for it to feed back into the assembly.The broken fork was the non metal , non damaging tool to help take off the o rings without marring the plunger and risk losing the vacuum property due to air leak s


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Re: Lunt LS50THa PT deassembly- the saga continues lol

Post by Montana »

Oh dear! I hope it gets fixed soon. I never like to touch anything at all :(

Alexandra


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Re: Lunt LS50THa PT deassembly- the saga continues lol

Post by krakatoa1883 »

Bring up this old discussion because I have just published a short note on replacing the o-rings for Lunt LS50, this is the link: https://imagesofoursun.wordpress.com/ma ... r-o-rings/

(for moderators, think this discussion should be moved to a different section of the forum)


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