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lunt LS 50 pressure tuner

knobby

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knobby

knobby

Posted
Posted

Love my Lunt but pressure seems to drop fairly quickly ... 30 seconds ish and it's gone , I've seen several notes of this so had a quick look at the o rings only to find there's just 1. Seems to have rebate for 2 but definitely just the one on mine .

Has anyone else got 1 or the 2 as I suspect should be there ?

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Tyson M

Tyson M

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Okay, I am currently going through this exact issue and I will document my experience. First and foremost, I am beyond impressed with Lunt Solar customer service. I will definitely do future business with Lunt. 

I bought a preowned LS50hta from an Astro forum. I wasn't able to tune it at all. I focused the disk on a monster sunspot, but I was unable to see any proms. Checking GONG Ha network, I saw some there. So I knew it was the pressure tuner. If you cannot focus the disk with the helical focuser you likely have a decontacted elaton from mishandling in shipping, not the pressure tuner's fault. Further inspection in my pressure tuner, it only had one o-ring inside.

So after reading online and contacting Lunt, The issue was with the o-ring/o-rings as you mentioned. Mine, even though preowned, was under warranty for 5 years. Purchased in 2014 so I was good to go, just had to give them the scope number. I was impressed and not expecting that they had transferable warranty. 

Lunt sent me step by step instructions of how to replace the o-rings, 2 new black o-rings and sent me their grease. This is important because it takes the guessing out of what grease and what size o-rings I needed. You need grease with high thermal/pressure properties but it is expensive. They didn't charge me a penny. Again, very surprised and happy.

Their instructions, were a little bit vague. I was sent a PDF that showed a description of how to deassemble the PT with pictures. Since they sent me two new o-rings, and the instructions showed the replacement of two o-rings and the PT has grooves cut for the placement of 2 o-rings, I thought my main problem lied with the fact I had ONE o-ring, not two. This makes sense on face value that it would lose air under these circumstances.

Well I deassembled the pressure tuner and regreased my bone dry threads, put two new o-rings on, and the PT would NOT screw back on. Under any circumstances of using my hands forcefully, or by feeding the first ring into the brass female attachment of the scope to work it in and then screw on, it simply would not thread back on.

I thought it was my lack of mechanical experience or tools, and I got frustrated so I thought of securing the scope in a vice like grip with my legs and forcing the PT with new o rings on....WITH A RUBBER MALLET.

This was a terrible idea and also a valuable learning experience. NEVER FORCE ON SOMETHING WITH THREADS. Self explanatory right? I broke the threads on the black aluminium PT casing by crossthreading them on the female brass end. I am thankful I didn't damage the threads on the brass part of the scope, as Lunt said that part was much harder to get and replace.

I sent my whole scope and broken PT in its case internationally to Lunt and they are fixing it for me- FOR FREE. Even though I messed this up on my own accord.

They will find a PT/ o-ring combination that will work. I paid for the shipping, which is perfectly fine and again, the great professionalism of Lunt employees is something worth stressing over and over. 

 

Here is the take away:

Lunt first sent me this in response to my issue:

As for the placement of O-rings: I would recommend that you remove the old O-Ring and only place one of the newer one that you just received, in the nearest (front) groove location on the brass male threaded component and give it a try for feel and force being employed to rotate black cylindrical (knurled) knob. Of course, you may have to wait for the replacement black cylindrical knob to attempt this trial. And only try placing one of the two newer O-Rings at a time; it sounds like having both O-Rings in place created an extremely hermetic condition that made it difficult to engage the black cylindrical knob onto the brass threaded housing. You want a hermetic seal that will eliminate any vacuum leaks, but, not to the point where you cannot rotate the black cylindrical knob. Try only installing one O-Ring as mentioned above and check for leaks and force required to rotate. Do apply sufficient vacuum grease (supplied) around the perimeter of the O-Ring to create a barrier, but not excessively.

 

So the moral of the story is that you do not need both O rings. Try one new one and go from there. Contact Lunt for a little care package of 2 o-rings and grease. They may charge you if the scope is not under warranty, they may not.  If they do, it is shipped in small packaging and I cant see it being expensive at all. Either way, they are more than helpful if you contact them by email or phone. 

 

 

 

 

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ArmyAirForce

ArmyAirForce

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My LS50THa has only one O ring. My pressure tuner failed in December. Going from detail to white light view in 30 seconds. Here's a video of what it did. It was only 3 months old. It was returned to the shop, and they sent it for repair under warranty. It took a while for a number of reasons, but I was sent back a completely new scope.

 

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Highburymark

Highburymark

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Knobby/Tyson,

If you do a quick search on SGL you'll find a couple of threads from last summer which deal with precisely the same issues. There you'll find the  "1 or 2 o-rings" debate covered in exhaustive detail, pictures of deconstructed pressure tuners, and advice on Lunt-friendly grease samples.

Please continue to post your experiences - there are lots of owners interested and we all want to get the best out of our scopes. 

 

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ArmyAirForce

ArmyAirForce

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Don't expect anything in a hurry from them. My scope was with them ( in Germany ) over a month for repairs, and in the end, they just sent a replacement, which could have been done within a couple of days. It seems they only have one person who can actually do any work on scopes, and as he was on holiday for two weeks, nobody else could look at my scope to carry out a repair.

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jam1e1

jam1e1

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may be worth contacting their European service centre (bresser GmbH germany i think) who handle repairs on their behalf. Had issue with focuser, which they repaired relatively quickly, though as above i had to wait around 1 week or so for lunt to initially respond

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FLO

FLO

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Posted
25 minutes ago, knobby said:

Emailed Germany today ...

Hi Knobby, is it one of ours?  

If it is please email us.  If it isn't then I recommend you contact your supplier, especially if it is only two weeks old :smile: 

HTH, 

Steve 

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knobby

knobby

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Too service as usual from FLO ... Cheers Steve, bought from a local shop in Kent , I just want Lunt to give a definitive answer about how many / where the I rings fit ! The retailer probably won't have that answer but appreciate your reply.

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jam1e1

jam1e1

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worth mentioning you've emailed Lunt too, they normally pass request on so maybe they can email them back to check request.....good luck with it, hope gets sorted soon. Again they were good for me and sorted my issue with focuser when had a lunt50

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  • 2 weeks later...
knobby

knobby

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The states finally got back to me, the newer LS50 has one O ring (most of the time) apparently the 2 make it hard to put back in after removal to de pressurise.

1 ring , at the rear position, mine seams ok now, I took the plunger out and spread the grease around a bit !

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