QHY11 incorrect work at Temp<-3C

[73km]

Hello, QjuHy!

I am user of QHY11 #0101608. Camera was supplied by QHY dealer in Russia.
Camera test at room temperature was performed well.
After that camera was assembled with real set up of the observatory.
Ambient temperature -12C.
Thermoelectric Cooler was switched off.
Normal rate of readout.
Used programm - EZCAP.

I have investigated picture of defocused star in prime focus at different temperatures.
Temperature was measured in three points:
1) Reading from EZCAP main window (sensor temperature)
2) Digital temperature gauge of gas flow at the output of camera "grid"
3) Ambient gas temperature

Temperature 3) was about constant -12C
Temperature 1) was changed by external gas flow heater directed to camera air inlet with step 2C from -12 to +5C.
At switched off thermoelectric Cooler the temperature 1) was equal to 2) with deviation + /- 1C

Following effect is observed:
a) Star picture disappear if temperature 1) is lesser than -3C
b) Active sensor  area (where signal takes place) decreased proportionally with temperature decreasing from +2 to -1C

The zip file with pictures at different temperatures you can load from place
http://mdeminsky.narod.ru/TEST.zip

Abbreviation of file's name:
30s_-12C-12O.jpg means exposition 30s, temperature 1) equals -12C, ambient temperature -12C

Used software
EZCAP 3.11
QHYCCD QHY11 ASCOM Camera Driver 1.1.0
QHY11 3.0 Driver

As I know, it is second QHY11 camera with similar problem here in Russia.

I would like hear any comments / advices from you.
Thank you.
Maxim

[QiuHY]

Hello,
        After we get the first report We have ordered a temperature box which can get -40C below zero to do the low temperature test.  This device will come this week then we can find the detail reason and solve method.


Best regards,

[Ivan7(rus)]

Hi, QiuHY
Russian dealer gives me bad qhy12 for testing.
I've attathed a lens to camera to get some image and took some shots in EZCAP.
It looks like almost the same problem - horizontal lines instead of an image, (horizontal pixels charge transfer isn't working), but this time it doesn't work at room temperature as well.

[Ivan7(rus)]

With my oscilloscope I've found 3 main signals concerning horizontal line reading process, RG, H1 and H2. All 3 signals are coming from cypress microcontroller, go via 22om resistors to another board (the round board under the ccd).

See picture,
As I understand, yellow an blue are H1 and H2, green is RG. Blue and green looks normal, have 0V - 3.3V range, but yellow has 0 - 0.2V range. I've looked at yellow signal before 22om resistor and after it, before it has range 0-0.8V, after 0-0.2V, so I think the target IC (to which the signals is coming to) has a shortcut in the input pin.

What is the name of the IC, that converts H1 H2 voltage range from 0-3.3 to the range, required by the ccd?

As I understand, this IC is the same in QHY11 and QHY12 round boards. Is that right? For now we here have already 3 cameras with this problem (horizontal charge transfer is broken).

[QiuHY]

Hello,

     This driver IC is EL7457.

      After our low temperature enviroment test. We have found the solution of the problem of QHY11.  It is due to a modification of the PCB board some month before.  The modification cause such an issue. We will make a document to show how to change back it.

      For QHY12. Has it relationship with the temperature. Or it is always problem no matter which temperature it is?

Best regards,

[Ivan7(rus)]

      After our low temperature enviroment test. We have found the solution of the problem of QHY11.  It is due to a modification of the PCB board some month before.  The modification cause such an issue. We will make a document to show how to change back it.

Great news!

      For QHY12. Has it relationship with the temperature. Or it is always problem no matter which temperature it is?

Can't tell exactly now. At room temperature it sometimes works, sometimes doesn't. I'll make some tests at cold temperature.

[Ivan7(rus)]

Finally found the issue with qhy12. When front part of the camera (part with the window and the glass) is removed - camera works fine, when I tightly screw front part to the camera - it immediately stops working. When I screw it off a bit - camera works again. I think, when I screw it tightly, the front part presses on a round board, and somewhere makes a shortcut of the H1 signal to the ground.

One solution is to make a 0.5mm thickness ring between front part and the body of the camera. Another solution is to cut the thread by 0.5mm on the lathe. I have small lathe at home, so I prefer second variant. Now I'm testing it, so far it works fine.

[QiuHY]

Hello,

       We will check where it shorted.  So this is the problem of the size of front part.  I will ask our factory to check it. Thank you to find it out.

       And for QHY11. Our engineer is writing a document. After we fixed it we have put the QHY11 in the low temperature enviroment at -40below zero and it works a whole day no problem.


Best regards,

[73km]

Hi QiuHY,

"After we fixed it... it works a whole day no problem"

Can we understand that like the problem  existence was confirmed and successfully solved?
 So after solution the camera works well at low temperatures now.


Maxim

[QiuHY]

Hello,

     Yes it is . The QHY11's low temperature problem is located and compeletely solved.

Best regards,

[73km]

Hi,
Promising news.
Please, give us guidance to get over the problem here in Russia.
Maxim

[CZB]

Hello,
    The QHY11's low temperature problem is located and compeletely solved.
     Please opreate follow the attach file.

Best Regards

[Ivan7(rus)]

Thanks!
We'll do here modification and check how it works.

[CZB]

Hello,
     About your QHY12 camera problem,can you take picture of the CCD drive circuit board?which the CCD on the circuit board,and we will check the problem follow your picture.



Thanks

[Ivan7(rus)]

Hello,
     About your QHY12 camera problem,can you take picture of the CCD drive circuit board?which the CCD on the circuit board,and we will check the problem follow your picture.

I've marked with pink arrow that pin, which has been shortcut to ground. As I remember, this wire is connected to pin 1 and 7 of both EL7457.