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Old 03-07-2016, 10:01 AM
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STXL corrosion issues

Three years ago I bought an SBIG STXL 11002 camera. I have owned two QSI cameras for the last 6 years and both performed very well at my observatory site and the one I still own continues to perform flawlessly. During the period I have owned the STXL, the camera has been sited 6km from the ocean at Clayton in South Australia. Prevailing winds during the day typically come from the south or south west. There is never any wind at night except when we get northerlies, so the air mass during that time is dry and rare. In the norm the air is probably highlyladen with moisture and with some salt. I have often witnessed heavy dewing on site to the point water is dripping off everything in the mornings.

About a year after I first bought the STXL, the camera had its first failure. It has been back to the US for repair 7 times. The first failure was to do with the sensor. Several trips back to the States were required to find the problem and eventually the camera was replaced. The last few trips back to the states started identifying another issue of corrosion of the PCBs in the heat sink bay. The first image shows the bay of the camera that contains the communications and power boards. The communications board is on the bottom and the power board on top. They are connected together with exposed pin connectors which have air passing through them. The heat sink is seen located in the same area as the boards. Air is drawn in over the heat sink and then pushed out via the vents on the side which can be seen in the first image. In short the moisture laden air is passing over the boards. Images taken over the last couple of trips have shown corrosion on the boards and pin connectors. Salt was even seen on the most recent images of the boards. This sort of damage is not covered by SBIG warrantee. Though I have to point out that SBIG has been very good with warrantee claims in the past 6 trips. They expedited the claims quickly and kept me up to date regularly. In short they have been very good on the whole.

On the last trip back to the states I was forced to buy and replace the two boards that are located in this bay. The cost was $2300 AUD which included labour and insurance. I was initially going to try to sell the camera and off load the problem. This design does not seem to work well in my location. I note that my onsite computers are desktops and exposed to the same conditions and drawing the same air into the boxes and never failed in 6 years for one computer and 3 years for the one with the STXL.

However, after some consideration and consultation with a few people including SBIG I considered doing what is called conformal coating to the PCBs. The PCB's are coated in a hard silicone seal that prevents corrosion to the boards and components. It is commonly used in environments with high moisture, chemical concentrations and salt levels. The connectors also need to be coated in silicone but not entirely. The pins need to have correct contact unhindered by silicone. I got some excellent advice from someone in our astronomical society who works with this sort of coating all the time. It was either this or take a huge loss on the camera and buy and FLI. Worth a punt I think. The AOX tech is a huge advantage and something I wanted to keep.

The other images show the PCBs during coating taking place with masking of the tops of the pins and silicone being applied to the pins. The camera is back to together again and I am glad to say working.

Will this work last and prevent corrosion long term? That I don't know yet. I hope so and I will have to give it a try. A gamble for sure but to keep the advantages of the system with short back focus and AOX integration I think it is worth it. I'll report if it does not work.
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  #2  
Old 03-07-2016, 02:52 PM
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bert (Brett)
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So to summarise:

You paid like 10k for a new sbig camera that didn't work.
Then paid them sbig 2k to band aid a design problem.
Then hopefully permanently fixed it yourself.

12 grand is kinda expensive for a DIY camera don't you think?

There was another post of an STXL owner that is at his wits end, posted to this forum that was removed shortly after.

I admire your restraint with the post. I would be at a wits end also if this was me. I'd be using terms like 'for for purpose' 'defective product' and be getting lawyered up.
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Old 03-07-2016, 03:24 PM
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Paul,

The downside of conformal coating is that it makes PCAs difficult to rework or repair but that doesn't matter if they're going to stiff you for a complete new one anyway. Hopefully, it will solve your corrosion problem.

The cost of conformal coating at time of manufacture is relatively small. It's a shame that few "amateur" astro products seem to be designed with their typical usage in mind. Brett makes some good points.

Cheers,
Rick.
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Old 04-07-2016, 03:50 PM
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I cannot believe the amount of crud you have had to endure with this so called Hi end camera. SBIG should be hung drawn and quartered for producing this "lemon". It certainly appears as though there is an inherent design flaw, which considering the cost is totally un-acceptable.
Based on your experience with this camera, if I was going to purchase a high end CCD, I would most certainly be looking elsewhere. This is not to say that all their cams are inflicted with this problem, but it most certainly is enough to stop me thinking about purchasing one.
As usual, I fully expect some flack for my response, but that is nothing new. One most certainly should not have to put up with these issues when purchasing what is supposed to be one of the "Rolls Royce" of imaging cams
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Old 04-07-2016, 04:05 PM
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multiweb (Marc)
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+1 After your feedback and Steve's I'd avoid S-BIG like the plague. Not because of their product faults but because of their after sales service.
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Old 04-07-2016, 04:13 PM
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Quote:
Originally Posted by bert View Post
So to summarise:


I'd be using terms like 'for for purpose' 'defective product' and be getting lawyered up.
Paul is a member of the bar I believe, so I reckon those thoughts may well have crossed his mind.
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Old 04-07-2016, 06:53 PM
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Well, this all very awkward, Ive got a STXL and its worked well for 3 years. I had a problem recently which took a long time to solve, but it appeared to be my fault basically (loose connector in the filter wheel). I sent the cam (only) in for repair, that went well and wasnt expensive, but a small problem was discovered during the service that was easy to fix but an interesting one I wasnt aware of. The shutter wheel was sluggish and caused constant shutter faults in testing with CCDops but not with DL5 on my rig. I think I did see heasitation in guiding exposures sometimes, but no errors. This tells me error capture/reporting is not the same in every app, not something I had considered before. The reason for the shutter sluggishness fault on my cam is interesting, the main chip shutter and guide shutter operate together, so during say a 40min exposure, the guide exposures are "electronically" shuttered. But if imaging is not active, and guiding is, both shutters operate on every guide exposure. I have my scope operated manually, so if imaging stops at say 3am, guiding attempts continue till 8am or so until I stop it. Between 3am and 8am the main and guide shutters operate every 3 seconds, thats 6000 actuations!. Do that for a few 100 days and I suppose things wear out. I would say having the main and guide shutter always operate together when not imaging is not smart design.

I have seen Steves fast disappearing post and with Pauls post now it doesnt look good for SBIG I must say. But, the kind of problems Steve was having, and others have complained about, which appear to be design faults, I havent had at all, so im thinking changes in hardware in production or more likely firmware have caused problems. Also, I think the capture application used makes a difference, not that that is a good excuse.

Paul has bought up a serious design fault IMO, the PCBs should not be exposed to the outside and in the fan airflow, FLI only has the cooling heatsinks exposed to the fan. I see some corrosion on my cams PCBs and the last cleanup showed much dust on the PCBs. I have the cam on 24/7 so some may say this is why, but remote operation with everything on 24/7 is common, it appears SBIG only considers power up for each imaging session, which is not always the case.

I dont think SBIG breakdown service is at fault generally, the one guy that does this trys hard, charges reasonably and is usually fairly prompt and helpfull. I think he is hamstrung by design issues he has no control over (although it shouldnt take 7 trys to fix something). Its "after sales support" feedback leading to proactive efforts to fix design issues thats the problem IMO.

Last edited by Bassnut; 04-07-2016 at 07:10 PM.
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Old 04-07-2016, 09:18 PM
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Paul,

That is certainly unlucky and bad news.

My recollection is you are only about 500m from the shores of Clayton Lake leeward of the prevailing winds so you would obvioulsy get more moisture laden air off the water than the average imager.

I know my local lake has suffered from historically high salinity and low ph levels and most of the Lower Lakes have also suffered including the Goolwa Channel of which I think Clayton Bay is part of, so I wonder if the salt and low PH levels might have contributed to the problem ?

It does seem like a design deficiency issue that the entire system is exposed to whatever is in the air that is being circulated through the fans.
Did you take any samples of the corrosion or salt build up ?
A simple analysis would be able to determine some of the constituents.

I hope you took some steps to neutralise the corrosion before you siliconed it - otherwise corrosion can be like a cancer and will continue - albeit slower.

I had some circuit boards started to malfunction (not my camera ! - but out of a machine) that got pissed on by a rat that found an entry point through a cable channel and decided to build a nest in the top of the nice warm cabinet !

Had to completey remove them, soak and wash them using various detergents and then neutralise them before using methylated spirits to remove any last traces of moisture and a final overnight dry out next to a heater.
They certainly smelled better and best of all they worked perfectly again !!

Rally
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Old 06-07-2016, 10:03 AM
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Quote:
Originally Posted by bert View Post
So to summarise:

You paid like 10k for a new sbig camera that didn't work.
Then paid them sbig 2k to band aid a design problem.
Then hopefully permanently fixed it yourself.

12 grand is kinda expensive for a DIY camera don't you think?
Thanks Brett. I am surprised that the boards are not conformally coated in the factory given the location of the boards. Perhaps SBIG will learn from this and make the relevant adjustments to the design.

Quote:
Originally Posted by RickS View Post
Paul,

The downside of conformal coating is that it makes PCAs difficult to rework or repair but that doesn't matter if they're going to stiff you for a complete new one anyway. Hopefully, it will solve your corrosion problem.

The cost of conformal coating at time of manufacture is relatively small. It's a shame that few "amateur" astro products seem to be designed with their typical usage in mind. Brett makes some good points.

Cheers,
Rick.
Yeah it is a minor cost from my own experience and yes conformal coating really makes working on the boards near impossible, but right now I need reliability. So either SBIG conformal coat, change the location of the boards or advise clients of the potential for this to happen in certain environments. The easiest course of action will be to conformal coat.

Quote:
Originally Posted by Exfso View Post
Based on your experience with this camera, if I was going to purchase a high end CCD, I would most certainly be looking elsewhere. This is not to say that all their cams are inflicted with this problem, but it most certainly is enough to stop me thinking about purchasing one.
I don't know exactly why the boards are located where they are but my guess is heat orientated. I have heard that Atik have a similar design for their large format camera and it has a similar problem.


Quote:
Originally Posted by Bassnut View Post

Paul has bought up a serious design fault IMO, the PCBs should not be exposed to the outside and in the fan airflow, FLI only has the cooling heatsinks exposed to the fan. I see some corrosion on my cams PCBs and the last cleanup showed much dust on the PCBs. I have the cam on 24/7 so some may say this is why, but remote operation with everything on 24/7 is common, it appears SBIG only considers power up for each imaging session, which is not always the case.
Fred, I think location environment makes a huge difference to how this problem plays out. However, even at your location having corrosion is indicative of an issue in my opinion.


Quote:
Originally Posted by rally View Post
Paul,

My recollection is you are only about 500m from the shores of Clayton Lake leeward of the prevailing winds so you would obvioulsy get more moisture laden air off the water than the average imager.

I know my local lake has suffered from historically high salinity and low ph levels and most of the Lower Lakes have also suffered including the Goolwa Channel of which I think Clayton Bay is part of, so I wonder if the salt and low PH levels might have contributed to the problem ?

It does seem like a design deficiency issue that the entire system is exposed to whatever is in the air that is being circulated through the fans.
Did you take any samples of the corrosion or salt build up ?
A simple analysis would be able to determine some of the constituents.

I hope you took some steps to neutralise the corrosion before you siliconed it - otherwise corrosion can be like a cancer and will continue - albeit slower.

Rally
The location of the observatory is about 500m from the River Murray, about 7 km from Lake Alexandrina and about 6 km from the Southern Ocean. I doubt Clayton would be worse than locations such as the tropics around the world. Certainly moisture laden but would that mean not using the camera in those locations?

The salinity levels experienced in the Goolway channel (part of the Murray River) disappeared after the drought ceased and this camera has not been exposed to those conditions. Though there might well be some saline content in the air after a day of onshore winds pushing it onto the land. I note though trees and shrubs are unaffected by any salt in the air. In fact trees, shrubs and plants in general thrive around that area.

I had the old boards shipped to me which contain the salt and damaged connections.

These boards are all new boards and had not been exposed to the environment at Clayton prior to coating.
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Old 06-07-2016, 11:14 AM
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bojan
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Looong time ago we (at company I worked for) used a lacquer (AL36 (??) I think it was called.. it was allowed by MIL standard) to protect military style radio equipment printed circuit boards.
Good thing about that lacquer was that it was solderable (actually it worked as solder flux), and was luminiscent when illuminated with UV light.
It had a very characteristic acid smell when not cured.

Electrolube protecive coating spray is very similar to this stuff (in terms of protection, smell and as solder flux).
Of course, it has to be apllied immediatelly after PCB assembly and washing, before final assembly into product.

I didn't know that such a reputable product (like SBIG camera) is not placed in properly sealed enclosure - I would expect better for the price.

On the other hand, Canon is not much better either.
I am repairing one 450D now, with corosion-eaten connectors and flex cables, the whole tracks are missing from the board, converted into green, non-coductive stuff.
We are not talking about $10k here, but still - just a better quality solder stop coating over the vis does not cost that much more to be prohibitive for a manufacturer who wants to be seen as selling a reliable product.

Last edited by bojan; 06-07-2016 at 11:27 AM.
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Old 06-07-2016, 11:54 AM
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Quote:
Originally Posted by bojan View Post
Looong time ago we (at company I worked for) used a lacquer (AL36 (??) I think it was called.. it was allowed by MIL standard) to protect military style radio equipment printed circuit boards.
Good thing about that lacquer was that it was solderable (actually it worked as solder flux), and was luminiscent when illuminated with UV light.
It had a very characteristic acid smell when not cured.

Electrolube protecive coating spray is very similar to this stuff (in terms of protection, smell and as solder flux).
Of course, it has to be apllied immediatelly after PCB assembly and washing, before final assembly into product.

I didn't know that such a reputable product (like SBIG camera) is not placed in properly sealed enclosure - I would expect better for the price.

On the other hand, Canon is not much better either.
I am repairing one 450D now, with corosion-eaten connectors and flex cables, the whole tracks are missing from the board, converted into green, non-coductive stuff.
We are not talking about $10k here, but still - just a better quality solder stop coating over the vis does not cost that much more to be prohibitive for a manufacturer who wants to be seen as selling a reliable product.

As it turns out I used an Electrolube product as recommended by the coating expert I have emailed. Electrolube recommend the same product to when I explained the environment.
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Old 31-01-2017, 02:54 PM
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Update

This is a bit of an update. Its been 7 months since this work was undertaken. Thus far the camera is working well and does not seem to have any corrosion present. Happily it appears the conformal coating has worked.

The camera has undertaken many imaging runs with seven objects imaged or in the process of being imaged. There was one night when I got a strange set of prison bars at the very end of the night on one image. I suspect this was a power outage and the UPS was not able to deliver all the power the camera needed. The dome was open in the morning too and this would seem to confirm a power outage. In any event, the artefacts have not been seen since.

I'll report again in 6 months with how the camera is operating. Fingers crossed. If I get past 12 months then I will have confirmed that the problem was a design fault and that perhaps it ought to be looked at for future designs. Time will tell.
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Old 01-02-2017, 08:49 PM
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Great news that the camera is working well, thank you for the update Paul.
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Old 01-02-2017, 09:48 PM
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Hi Paul,
sorry to hear all about that corrosion problem.
I am an electronics technician & have conformally coated 100s of PCBs.
Yes - conformal coating is a wise move.
It is a hard process to properly mask everything & also to not have the coating
leak underneath the masking tape.

However - it is sensible to use non-acidic silicone such as Dow Corning 738
because most of the others have an acidic cure & will damage the metal on a PCB over time.

cheers
Allan
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Old 12-07-2017, 09:51 PM
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12 month update:

Since doing the conformal coating 12 months ago the camera has generally stayed in operation. There has only be one incident which required repair to one of the boards. It was a small fuse that blew and that fuse enables the filter wheel to be powered. I contacted the SBIG repair tech and he led me to resolving the problem and I fixed it myself. I cleaned off the conformal coating, desoldered the joints and resoldering the fuse. That was a couple of months ago.

I can say that I found no evidence whatsoever of corrosion on the boards or pins whilst doing the recent work. The gold on the contacts was still intact. The fact that the camera is still working after 12 months which, before it struggled to remain operational for greater than 5 months at a time, says a lot to me.

Now beware if you are planning on protecting your camera from corrosion by conformal coating, SBIG will not cover your camera because you have modified your boards and modification is not covered by warranty. I might also remind you that SBIG will not provide warranty for corrosion either. Looks like catch 22. Perhaps the design ought to change.

For me all I wanted right from the start was a camera that would operate for years at a time without problems like my QSI. I wanted the AO tech and the integration of the AO into both camera and software. I think I have got what I wanted albeit I had to do the work myself.

I'll report in another 12 months.

Last edited by Paul Haese; 12-07-2017 at 10:07 PM.
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Old 12-07-2017, 11:04 PM
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Glad to hear that corrosion is no longer an issue.
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Old 16-04-2018, 07:15 PM
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Update-20 months plus since conformal coating

Camera is still running and no corrosion visible. The camera does have a glitchy behaviour from time to time with prison bars being present in the read out. It has always done this since the first repair. I suspect a bad connection on the sensor board.

Overall the conformal coating worked. SBIG don't appear to have listened to my suggestion to conformal coat their coms and power boards which are exposed to the air. I am not sure if their new line of cameras will have this same problem.
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