Solving SBIG frosting issues - Page 2

[1ponders] (Paul) · #21 20-02-2011, 08:38 AM

Cheers thanks for the link Dennis. I don't know if it would be any good at my place (draughty ol' little qlder) but it gives me food for thought for the bottom room of the observatory.

I did think of moving to the Simpson Desert, but it doesn't seem any better out that way this year.

spearo (Frank) · #22 21-02-2011, 05:09 PM

yep
i had similar issues with the STL 11000

I was even going to get a spare dessicant plug at some point in desperation.

I now find that as JOhnG says, if I have the camera running , even at room temp while i set up the rest 1/2 hour to an hour, the issue has gone

frank

Bassnut (Fred) · #23 21-02-2011, 05:44 PM

mmm, supprised at the grief with dessicant on SBIGs. Ive had 3 of them and found they could always go hard to -10 to -20 regardless of ambient with no frosting (even with water cooling). If at anytime there was frosting then I baked the plug and all was well again. Any frosting at all was the the trigger for a rebake. I found the plug lasted 6-12 mths.

Stigandi (Rob Stinson) · #24 24-02-2011, 07:43 PM

Sounds like a seal problem. I've got a ST4000XCM. After a year or so of vigorous use it started to frost. More and more over time. I did the normal plug recharge and it has been frost free for the past year+. No special bags, gas, etc. The o-ring seal is the key to this, unless there is a leak elsewhere. I don't know enough about the guts of the camera to know where other leaks could be. Good luck..

Rob

[1ponders] (Paul) · #25 24-02-2011, 08:11 PM

That's what I thought too Rob, but I've checked and checked the seals, even getting SBIG to send replacements. I'm just about to crank it up for the first time after sitting and dehumidifying for a few days.

[1ponders] (Paul) · #26 24-02-2011, 08:24 PM

Woo hooo cranked it straight from room temp to -13 deg and no sign of frosting

Very happy

Now for some clear skies

Terry B · #27 24-02-2011, 08:41 PM

allan gould · #28 24-02-2011, 10:28 PM

Paul
Pleased that your issues appear to be resolved. Just so sad about the WO fungus.

[1ponders] (Paul) · #29 24-02-2011, 11:14 PM

thanks Allan and Terry.

the WO appears to be the least of my problem. I noticed some fungus on the inside of the corrector of the SCT tonight. On closer inspection I found it also on the mirror. Think it might be time for a send away and a professional clean.

Octane (Humayun) · #30 24-02-2011, 11:28 PM

How hard would it be to get the William Optics one cleaned?

That is a real worry. : (

H

[1ponders] (Paul) · #31 25-02-2011, 06:41 AM

I'm hoping that I can get the lens cell off and the fungus is only on the inner surface. If I have to I'll send it away. Its my favourite imaging scope.

This years weather has been terrible for glass surfaces.

higginsdj · #32 26-02-2011, 03:04 PM

I've never had issues with my ST-8E over the past 10 years - but it could be the low RH in the house whenever I bake the dessicant (<20%)

Cheers

stevous67 (Steve M) · #33 20-08-2011, 04:09 PM

Not sure if you will see this post Paul; I'm wondering how your frosting issue is going?

For over 8 months I was using my STL11k, and then serious frosting developed. I recharged the desiccant, and the problem return immediately. Upon a second inspection, I found all retaining screws to the CCD housing were loose. Obviously the seal to the CCD chamber was not secure. This may have resulted from the vibrations from the AOL.

My friend Dave gave me 2 bags of silica gel to try. These are currently cooking in the oven. I've got a plastic tub with a sealable lid, and in one hour I'll take the bags and put these into the box with the STL leaving the CCD chamber open. These will stay sealed together over night, to the end of tomorrow. I'll cook the desiccant plug again tomorrow, putting everything back together then. As for the retaining screws, I'll be securing these at the end too, hoping this will help clear the moisture.

Going to Border Stargaze this next week, so I'm hoping big time for success, as the weather may in fact allow a few hours of imaging for a change.

Cheers,

Steve

Peter Ward · #34 21-08-2011, 08:26 PM

Not surprisingly I've owned many SBIG cameras over the years....and have honestly had minuscule problems with CCD icing. That said I have serviced a handful of cameras that have a penchant to ice up.

The drill is to desiccate the desiccant cylinder: it goes into a high vacuum chamber and gets baked at 90 centigrade for a few hours. Those familiar with the dark art of hyper sensitizing photographic film will understand why this works *really* well.

I then flush the chamber with Argon to get it to 1 atmosphere before cracking the seal.

The camera head also gets flushed with a low pressure Argon gas fill and is quickly plugged with the revamped desiccant cylinder. Argon is a noble gas hence won't cause any nasty corrosion problems.

Hope that helps.

So far so good. Cameras that I suspect have leaky seals last around 6 months or more. Most last 2 years.

allan gould · #35 22-08-2011, 06:37 PM

While at Astrofest I happily imaged night after night with my QHY8 just replacing it in the airtight case with the desiccant and another batch of silica gel in a bag. Just removed the small rubber plug and placed the camera warm into the case. Never had a problem but imagine my absolute amazement after imaging til 2pm one night and the fog and dew rolled in that I took the camera off the scope and went to remove the plug to put it into is desiccant dried case to find I had not put the plug into the camera to seal it against moisture. So the whole night it had been running open to the atmosphere!!!!!!!
No damage done but there you go. The next Few nights the camera still performed perfectly. Just love the qhy8 and some of it's idiosyncrasies.

Paul Haese · #36 22-08-2011, 09:45 PM

Quote:

Originally Posted by Peter Ward

The drill is to desiccate the desiccant cylinder: it goes into a high vacuum chamber and gets baked at 90 centigrade for a few hours. Those familiar with the dark art of hyper sensitizing photographic film will understand why this works *really* well.

I then flush the chamber with Argon to get it to 1 atmosphere before cracking the seal.

The camera head also gets flushed with a low pressure Argon gas fill and is quickly plugged with the revamped desiccant cylinder. Argon is a noble gas hence won't cause any nasty corrosion problems.

Peter I will send my STL11 when it needs doing if you don't mind. What do you charge for the service?

Peter Ward · #37 22-08-2011, 09:55 PM

Quote:

Originally Posted by Paul Haese

Peter I will send my STL11 when it needs doing if you don't mind. What do you charge for the service?

I have to be careful on IIS about this stuff.... a certain website will have some details

Paul Haese · #38 22-08-2011, 10:22 PM

Quote:

Originally Posted by Peter Ward

I have to be careful on ISS about this stuff.... a certain website will have some details

Thanks for the tip Peter. I will go and take a look.