Lunt LS60 & USB Controller

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Lunt LS60 & USB Controller

Post by Alto » Wed Jun 03, 2020 10:02 am

Hi all,

Does anyone use the USB Pressure Tuner Controller from Lunt.

I have one attached to a Lunt LS60.

Despite having both ( unused ) for a while ( long story ) I've noticed that the tuner suggests there's a leak in my chamber, as it allows pressure to drop by 0.3psi from its setting, then builds by 0.4psi - in a cycle.
I've changed both rings - no difference. I've reduced the pipe to 18 inches as a test - no difference.

Question is, do I have a leak from the inner chamber, or is this 'normal' behaviour for the controller.
Even if there is a leak the controller is keeping me as close on-band as possible, so in that sense it remains workable. :seesaw

Both now out of warranty.



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Re: Lunt LS60 & USB Controller

Post by Highbury Mark » Wed Jun 03, 2020 1:05 pm

I have one but have never experienced any drop in pressure. I’ve often thought the connection between the pipe and scope/piston could be more robust - ie if there was a proper plug and socket - but it’s always worked well.
Maybe you should go back to the manual tuner and see if you can detect any fall in pressure over a long period of time - with features softening?


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Re: Lunt LS60 & USB Controller

Post by Alto » Wed Jun 03, 2020 2:49 pm

Thanks. It's a possibility I suppose.

Incidentally, did you get two sets of "O" rings with your controller - large and small - Do you know what the smaller ones are for?



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Re: Lunt LS60 & USB Controller

Post by Highbury Mark » Sat Jun 06, 2020 6:10 pm

Alto wrote:
Wed Jun 03, 2020 2:49 pm
Thanks. It's a possibility I suppose.

Incidentally, did you get two sets of "O" rings with your controller - large and small - Do you know what the smaller ones are for?
No - I just got two o-rings that fitted the piston, but I did buy it secondhand. Can’t imagine what the smaller ones would be for.


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Re: Lunt LS60 & USB Controller

Post by Alto » Sun Jun 07, 2020 6:27 am

I'm waiting for some sun, to test the standard tuning setup.

In the meantime, I've removed the pipe at the 'scope end and firmly clamped it. When the controller is activated it goes through the same pulsing - fall in pressure of 0.3 psi, recovering by 0.4 - in a steady cycle. Seems suggestive.....



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Re: Lunt LS60 & USB Controller

Post by Highbury Mark » Sun Jun 07, 2020 4:54 pm

In hindsight it doesn’t sound like a leak is causing your problem. Occasionally my tuner doesn’t stay at its set pressure - it gets there (or very near to the pressure I’ve dialled in) but then keeps faltering, never settling - whenever this happens I just change the target pressure level by a small amount, and then it tends to hit that level and stay there. So it’s never been a problem.
Have you spoken to Lunt about it?


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Re: Lunt LS60 & USB Controller

Post by Alto » Mon Jun 08, 2020 6:15 am

Yes, Faye said she was looking into it for me....I guess they're rather busy.

I've seen past occasions like yours when it doesn't stay targetted, but a small change sorts that - but this is all the time, even with pressure at 1 psi.....



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Re: Lunt LS60 & USB Controller

Post by Highbury Mark » Mon Jun 08, 2020 3:59 pm

Ah ok - sorry I can’t suggest a solution. Bulky thing to send off to be repaired too.


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Re: Lunt LS60 & USB Controller

Post by Alto » Tue Jun 23, 2020 6:37 am

Advice from Lunt.

There's a spring inside the unit that might need a bit of a stretch.

It's not a common occurrence, but it seems they've had previous instances cured by a stretching.... :mrgreen:



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Re: Lunt LS60 & USB Controller

Post by Alto » Fri Jun 26, 2020 8:08 am

A spring stretch has a made a small improvement. Sadly it's still not producing a steady pressure.



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Re: Lunt LS60 & USB Controller

Post by solarnoob » Fri Jun 26, 2020 8:10 pm

I received my USB Pressure Tuner Controller last week, and I tested it this morning with my Lunt 100. It is somewhat bulky, but it is much better than tuning the scope manually; the pressure stayed on target (tolerance is 0.4 PSI) during my 2-hour session. It even includes a "Goto pressure" setting; I am never touching that tuning knob again!
:beanie:

Frank


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Re: Lunt LS60 & USB Controller

Post by Alto » Sat Jun 27, 2020 6:38 am

solarnoob wrote:
Fri Jun 26, 2020 8:10 pm
I received my USB Pressure Tuner Controller last week, and I tested it this morning with my Lunt 100. It is somewhat bulky, but it is much better than tuning the scope manually; the pressure stayed on target (tolerance is 0.4 PSI) during my 2-hour session. It even includes a "Goto pressure" setting; I am never touching that tuning knob again!
:beanie:

Frank
It's definitely worth it - when it works properly!!!!

I wish they'd update the crappy PC app.

p.s. what sort of pressures do you need to be on target - I've varied, on different sessions, from 12.4 to 18.1 psi....



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Re: Lunt LS60 & USB Controller

Post by solarnoob » Sat Jun 27, 2020 2:11 pm

Alto,
If that helps, I can run whatever test you'd like with mine so that we can compare notes. Let me know.
Frank


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Re: Lunt LS60 & USB Controller

Post by Alto » Sat Jun 27, 2020 2:16 pm

Thanks Frank - just a hint on what kind of pressure settings you need to be on target.

I'll post a photo of the insides when next out in the shed - it's a weighty unit and most of the weight seems to be a steel box inside a steel case, that plus a hefty battery!



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Re: Lunt LS60 & USB Controller

Post by Alto » Sun Jun 28, 2020 10:35 am

The inside of the inside (!)
IMG_20200628_094846.jpg
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Re: Lunt LS60 & USB Controller

Post by marktownley » Sun Jun 28, 2020 10:40 am

I bet your leak is from one of those many pipe joints, fire it up so it is pressurising the Lunt and then systematically go round each joint / coupling - put a bit of spit / washing up liquid (whatever really!) on each joint and look for the bubbles - there's your leak then. Same principle as the bicycle tire inner tube and a bowl of water to find the puncture. Putting the whole unit above in a bowl of water is probably a bad idea.

When you've found the leak depending on where it is will dictate the fix.


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Re: Lunt LS60 & USB Controller

Post by Alto » Sun Jun 28, 2020 10:56 am

Hi Mark - I've tried that one......



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Re: Lunt LS60 & USB Controller

Post by marktownley » Sun Jun 28, 2020 11:07 am

Wheres the leak? on the accumulator tank?


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Re: Lunt LS60 & USB Controller

Post by Alto » Sun Jun 28, 2020 11:16 am

I've no idea Mark - there's little more I can check. I wonder if perhaps there's a dodgy sensor ( where that length of pipe reaches the circuit board ). If I squeeze that bit of pipe the pulsing stops but that might be a poorly executed test.



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Re: Lunt LS60 & USB Controller

Post by Alto » Sun Jun 28, 2020 2:36 pm

It seems to be something to do with the spring - though I can't work out how the valve works given the way it's assembled. I've re-stretched and twisted the spring - it's a wee bittie cheap looking! - and I've got the pulse down to maybe 4 a minute rather than 10-15 a minute - so some improvement!



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Re: Lunt LS60 & USB Controller

Post by marktownley » Sun Jun 28, 2020 8:46 pm

Post up some pics. Sounds like it's a mechanical predicament. I'm sure it's fixable.


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Re: Lunt LS60 & USB Controller

Post by Alto » Mon Jun 29, 2020 9:00 am

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Re: Lunt LS60 & USB Controller

Post by marktownley » Mon Jun 29, 2020 3:04 pm

How tight is that o-ring seal around the brass rod?


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Re: Lunt LS60 & USB Controller

Post by Alto » Tue Jun 30, 2020 6:19 am

Hi Mark,

It's tight on - I've added a smear of silicon. There's resistance as it enters the chamber.



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Re: Lunt LS60 & USB Controller

Post by solarnoob » Wed Jul 01, 2020 3:35 am

Alto wrote:
Sat Jun 27, 2020 2:16 pm
Thanks Frank - just a hint on what kind of pressure settings you need to be on target.

I'll post a photo of the insides when next out in the shed - it's a weighty unit and most of the weight seems to be a steel box inside a steel case, that plus a hefty battery!
Not sure if this is what you are looking for. See pictures below, I tried a few PSI ; it took seconds for the target PSI to be reached.
Hope this helps.

Frank
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