Pressure Tuning Leaks on a Lunt

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rray6
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Pressure Tuning Leaks on a Lunt

Post by rray6 »

I have a question concerning my equipment that someone might be able to answer. I have a 10-year-old Lunt LS-80THAPT-B18F with the DSII internal double stack module. I was viewing the sun yesterday from my New Mexico observatory and I noticed that the pressure tuning knobs for both the telescope and the DSII unit seemed to be turning easier or more freely than I remember. I thought there used to be more resistance especially toward the end of tightening. I also noticed little change in the images when I loosened and tightened the knobs - at least not as much change as I remember. Is it possible that I don't have as good a seal as originally and the pressure tuning knobs are leaking? Is there something I can do to fix this (if it is a problem) - like adding some sort of grease on the tuning knob threads? I have not done much maintenance on this scope but it has always performed well for me. If anyone has any suggestions, I would appreciate hearing them. Thanks.

-Robert


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Re: Pressure Tuning Leaks on a Lunt

Post by marktownley »

I fished out my LS50 the other day and found the same. I haven't tried it, but also figured greasing the threads would help. I haven't done it yet, and not sure what sort of grease it is. I know you can buy the grease from Lunt.


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Re: Pressure Tuning Leaks on a Lunt

Post by JochenM »

Hi Robert

As Mark already pointed out, adding some grease to the threads is probably a good place to start. When I bought my LS50 a few years back, its threads were basically bone-dry and I added some simple silicone grease you can find in any DYI store; never had any issues with it. Additionally, inside the tuner knob there's an o-ring to keep things sealed. If that one has seen better days (you know how rubber seals get over time), it might be worth replacing it (Lunt sells them for a few €/$).


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Re: Pressure Tuning Leaks on a Lunt

Post by rray6 »

Thanks Mark and Jochen for the suggestions. New Mexico climate can be harsh on things like grease and o-rings. I sent an email to Lunt yesterday detailing the issue. Hopefully, they will get back to me soon with some direction. I had been planning to put some silicone grease on the threads but will wait and see what Lunt says first. :bow :bow

-Robert


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Last night as I lay in bed looking up at the stars in the sky, I thought to myself -- "Where the heck is the ceiling???"

www.redshift48.com
Lunt LS80 DSII B1800 f/7
WO 132mm f/7
Celestron 9.5 Edge HD f/10
Stellarvue 80mm f/7 Raptor SVR80ST2
WO Z73ii f/5.9 APO
Lunt CaK B1800 Filter and Baader Herschel Wedge (Photo)
PGR Grasshopper 3.0 (ICX687 - mono)
Player One Apollo M-Max IMX432
ZWO ASI178MM and ZWO ASI174MM with filter wheel
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ZWO ASI2600MC-P
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Re: Pressure Tuning Leaks on a Lunt

Post by Highbury Mark »

I’d also suspect the o-ring if the piston’s getting easier to turn and the grease doesn’t improve things. Lunt used to send out replacements for free.


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Re: Pressure Tuning Leaks on a Lunt

Post by hopskipson »

I had a similar problem with my LS80 that I got used on Astromart. It’s 11 years old and the o-rings got soft. After replacing them I still had a leak on the DS unit. I sent it back to Lunt and the collimating lens was chipped and leaking. They replaced it for $40. Now it works with no problem.


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