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Turning off cooled CMOS

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#1 gdsolz

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Posted 28 January 2020 - 09:53 PM

Sorry if that might be a dumb question, but I'm a bit worried about turning off my QHY163M, is there a special procedure to turn it off?



#2 joshman

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Posted 28 January 2020 - 10:02 PM

I would just make sure you warm the sensor up slowly, to avoid thermal shock. Then just turn off the power. note that the camera will still be "On" if it's connected to a computer.



#3 Cfreerksen

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Posted 28 January 2020 - 10:45 PM

+1 on the slow warming and cooling. Most good AP software has an automated cooling and warming option built in. The larger your sensor the more chance you could damage it by thermal shock IMO. If you don't have that just increment/decrement the temperature the temperature setting a couple degrees C every minute or so. I use a warming and cooling time of 7 minutes. So far so good. And as stated, the camera turns on when it is plugged into a USB jack and the computer is running even though it may not be connected in your software.

 

Chris


Edited by Cfreerksen, 28 January 2020 - 10:48 PM.

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#4 Stelios

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Posted 29 January 2020 - 02:49 AM

+1 on the slow warming and cooling. Most good AP software has an automated cooling and warming option built in. The larger your sensor the more chance you could damage it by thermal shock IMO. If you don't have that just increment/decrement the temperature the temperature setting a couple degrees C every minute or so. I use a warming and cooling time of 7 minutes. So far so good. And as stated, the camera turns on when it is plugged into a USB jack and the computer is running even though it may not be connected in your software.

 

Chris

The camera turns on when you plug in the connected USB jack, but it's not cooling unless it's connected to power--at least that's my understanding. 


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#5 schmeah

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Posted 29 January 2020 - 08:27 AM

I would just make sure you warm the sensor up slowly, to avoid thermal shock. Then just turn off the power. note that the camera will still be "On" if it's connected to a computer.

So I always read this. I am certain that most of us have had many sudden unattended software shutdowns, where you come back to your rig to find everything (including the camera) was suddenly disconnected. I’ve never seen a problem from this. So what exactly are the risks from “thermal shock”?

 

Derek


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#6 bmhjr

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Posted 29 January 2020 - 11:10 AM

So I always read this. I am certain that most of us have had many sudden unattended software shutdowns, where you come back to your rig to find everything (including the camera) was suddenly disconnected. I’ve never seen a problem from this. So what exactly are the risks from “thermal shock”?

 

Derek

"Temperature control methods also have an impact on thermoelectric module reliability. Linear or proportional control should always be chosen over ON/OFF techniques when prolong life of the module is required."

 

https://thermal.ferr...e/thermalref10/



#7 joshman

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Posted 29 January 2020 - 05:28 PM

So I always read this. I am certain that most of us have had many sudden unattended software shutdowns, where you come back to your rig to find everything (including the camera) was suddenly disconnected. I’ve never seen a problem from this. So what exactly are the risks from “thermal shock”?

 

Derek

The real danger from thermal shock comes if you cool it down too quickly. Sharpcap is real bad for this, or maybe it was the QHY drivers, but it would always start out the cooler at 100% power whenever I connected my 178mono. Don't underestimate the power of your camera cooler, in my experience it could take that sensor from ambient 30c down to -10c (and lower) VERY quickly (from memory, in about a minute)

 

that being said, I would also advise warming the sensor up slowly as well.


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#8 NuclearRoy

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Posted 29 January 2020 - 06:34 PM

+1 joshman (also +1 on always using the warming tool)

 

pokeshave, on 17 Sept 2016 - 6:59 PM, said:

The only real risk of thermal shock is during cool down. A TEC can cause a temperature change of tens of degrees Celsius per second. If you subject the sensor to 100% TEC cooling, the substrate in contact with the TEC will cool much faster than other parts of the sensor. This steep temperature gradient can cause the adhesives used to bond the sensor components together to weaken or fail or can even cause the sensor itself to fracture. That's why we cool gradually.

Warming up, on the other hand, is far less troublesome. If you suddenly lose TEC power, the sensor, TEC and heat sink have a good bit of thermal inertia and will all warm up gradually at roughly the same rate and a lot slower than is possible in reverse with cool down.

So, in short, if you suddenly lose TEC power, don't sweat it. You won't hurt anything.

Tim

 

Good call Tim. Sam agrees with you, and I'm pretty sure he knows about this stuff :)

 

Re: ASI1600mm-C ASCOM driver
Post  by Sam » Thu Sep 15, 2016 3:06 pm

Hi Christian
this is a protect method as you know
program crash is just behave which is not normal

there is no thermal shock if the TEC stop cooling and warm by air
and it's worse if user forget to turn it off and keep the TEC running for a very long time
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Location:lon=120.6 lat=31.3
SuZhou China


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