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Old 14-04-2018, 05:36 PM
pjphilli (Peter)
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Drying QHY9 Camera

I appear to have moisture problems with my QHY9 camera.
I am attempting to follow the procedures shown at QHYCCD.com/FAQQHY9.html in the section titled "drying QHY9 camera"

In part the text says "After removing the top circuit board" it then says "remove screws off the CCD annular seal space" and lift it up so that "a little gap is used to dry the annular seal space". It then proceeds with putting the camera in the "drying box for more than 10 hours" which I have prepared with suitable desiccant. The camera is sitting in it at present but without the above gap to dry the seal space.

I have a problem in removing the annular seal screws. The heads appeared to be buried in their slots which have some soft filler over the heads. Do these screws required a special screwdriver head (other then the normal flat or star heads)?

Another question: I usually run my camera straight down to -25deg C which temperature it appears to reach quickly. I have seen suggestions that it is better to slowly reduce the temperature to the desired level. What is the reason for this which does not seem to be included in my QHY9 operating instructions? How long should "slowly" take?

Help would be appreciated. Peter
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Old 14-04-2018, 05:59 PM
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Bart
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Peter,

For help with your camera, contact Theo at Gama Electronics. He is very helpful and knowledgeable. My guess is that the screws will be a Phillips head of some denomination and they likely have glue in them. Use a very small flat bladed jewelers screwdriver or a sturdy pin to pick out the glue and go from there. The QHY9 also comes with a screw in desiccant plug that can be used during the operation of the camera to help with moisture.

I'm not sure on how slow some take it, I have SGP set to cool to -20 over 5 minutes and to warm over 5 minutes. I never run any lower than -20 and am able to maintain that all year round.

Hope that is some help.

Cheers,

Bart.
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Old 14-04-2018, 07:29 PM
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RobF (Rob)
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Definitely talk to Theo before doing any surgery.
Its very unlikely you need to open that inner chamber - and would advise not to without consulting with Theo. Any moisture issues with my 9 have always been the outside chamber, and that is rare with desiccants in use.
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Old 14-04-2018, 10:51 PM
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alpal
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Hi Peter,
there is dry Argon gas inside the sealed chamber.
You can't remove it unless you have that special gas in a gas can to replenish it.
That's done with a plastic bag full of Argon with the camera inside it.
The QHY9 is not sealed inside for any of the other parts.
There is a gap between the connectors on the QHY9 case & the outside air.
I slowly cool mine to -30 degrees every time I use it.
By slowly I mean 5 to 10 minutes.
I first set the temperature to +5 degrees & then leave it for 1 minute ,
change it to -10 degrees then -15 then straight to -30 C.

When warming up I do it slowly as well in the same way.
You need to put the camera into manual to adjust the temperature
before connecting the 12 Volts for the peltier cooler.
If you leave it in auto at -30 it will jump all the way down & possibly crack the chip.
A sudden temperature shock can crack the KAF8300 chip.
I think there is a heater around the camera chip seal which should remove all the moisture from the glass cover.

I've never had any problems with dew or moisture buildup.

The QHY9 is a wonderful camera.
The only problem I ever had is that fast download of data
causes horizontal black lines from bright stars and 4 times the camera noise.
Always download the data using slow download.

cheers
Allan
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Old 15-04-2018, 12:28 PM
pjphilli (Peter)
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Thanks all for this useful information. I was a bit wary of opening up the inner chamber so I will leave this and only dry the outer workings. Some much for the QHYCCD FAQ! Their suggestion would have left dry air only in the inner chamber.
Interesting about the slow cooling - I have not seen this mentioned in the (slim) instruction manual but I can easily follow this using my Nebulosity software.
I am quite happy otherwise with my QHY9 but have fond memories of my old QHY8, bought second hand but still did four years of service before it failed completely. Sure it had moisture problems but these were easily fixed.
Cheers Peter
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Old 15-04-2018, 01:07 PM
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astronobob (Bob)
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Hi Peter,
I have the qhy10 and when cooling down, the default temp can vary because the default is not governing the actual temperature, but governed/controlled by the power level, default at 50% power, and is safe for start up & takes the camera down approx 20degs below ambient, I leave it there for a few minutes, whilst booting the lappy ect, then bump the power to 70% for another 5mins whilst focus & framing etc & maybe 80% during summer. Then tweek the power to set an appropriate chip temp, -20, -25, or -30 depend seasons !
Warming up after session, as soon as last frame taken. back power level down by 20% for 5 mins, then another 20% taking it down to between 30-40% for 5 mins, Last step, all safe to turn off
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Old 16-04-2018, 02:51 PM
pjphilli (Peter)
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Thanks Bob, I will keep your advice in mind when next using the QHY9. In view of the price of this camera it is surprising that a more comprehensive handbook does not appear to be available. I recently bought a relatively cheap colour (non astro) camera and it came with a very comprehensive handbook.

I drive my QHY9 with Nebulosity software which has a setting for the QHY9 whereby a temperature is selected and the camera proceeds to cool to that point. In my case the base temperature is ambient and when I set it at -25degC it appears to move down to this temperature over a period of a few minutes. Meanwhile I proceed to set up my astro gear, train the guiding and then go to the object and commence imaging - this takes about 20 mins (barring fumbles!) which should permit the QHY9 temperature to stabilize. I would hope that the camera stayed at the nominated temperature as I take darks after the imaging session. However, since the camera noise, even with 15min subs, is negligible at -25degC the use of the darks is mainly to remove hot pixels.

By the way, the apparent icing or moisture problem I see occurs progressively after the first initial good images and appears as an increasing dark band across the middle of the screen image of the feint nebulosity. This occurred when I was imaging the Carina nebula. I then tried a similar length image on a nearby star cluster where I suppose because of the relatively brightness of the stars, no evidence of the dark band was at all evident.

I guess there are two opportunities for dewing if not directly on the imaging chip, ie on the glass cover of the sealed chip box or on the additional glass in the camera nose. I have been drying the camera for a couple of days and the next time I use it if the above problem recurs I will have a look into the camera nose to see whether I can see any evidence of dewing. With my old QHY8 I recall I had to fit a small heater on the camera nose to overcome a dewing problem there. All good fun!
Peter
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