An investigation of the camera cooling capabilities of the  SBIG ST-10XME camera were made in an attempt to understand poorer than normal cooling performance in session 678.

2019-08-02, S678  vs 2019-08-08, S680
Looking back at session S678 (ambient temperature +11°C) when the camera was unable to achieve the intended regulated CCD temperature of -15°C despite , it is noted that the camera was producing 24°C of cooling below ambient (where ambient is taken as the UPB Env. Temp) when running at 100% power compared to the 25.5°C of cooling required. This resulting in unstable CCD temperatures that were up to 1.5°C higher than the intended regulated temperature.

This can be compared with the latest session S680 (ambient temperature +11.5°C) where the camera was able to produce 26.5°C of cooling below ambient (at 75% power) to achieve a stable CCD temperature of -15°C,   and later on produce 28.5°C  of cooling when operating at 100% power when set point increased to an overly ambitous -20°C.

Whilst fan was shown to be operating during a later daytime test, it is concluded that the camera's fan, was probably not operating during session S678. The reason is unknown.

Camera Cooling - Earlier Session 2019-08-02, S678)

Camera Cooling - This Session 2019-08-08, S680)

Looking at some other sessions:

2019-08-03, S679
During session S679 (ambient temperature +11.5°C)  the camera produced around 21.5°C of cooling below ambient (at 65% power) to achieve a stable CCD temperature of -10°C.

Camera Cooling - Earlier Session 2019-08-03, S679)

2019-05-09, S677
During session S677 (ambient temperature +2°C) the camera was producing around 27°C of cooling below ambient (at 80% power) to achieve a stable CCD temperature of -25°C when at 00:09 it suddenly could produce only 25.5°C of cooling at 100% power. This was sufficient to maintain the intended setpoint temperature and the CCD temperatures  rose to being 1°C higher than the intended regulated temperature.  Was this change in cooling performance caused by the fan going off ?

Camera Cooling - Earlier Session 2019-05-09, S677)

2019-04-22, S676
During session S676 (ambient temperature +8.5°C) the temperature set point used (-20°C) was pushed too low, which demanded the camera to produce 28.5°C of cooling below ambient. Whilst the camera could get moderately close to this amount of cooling during initial cooling at 100% power, this was not sustainable and the camera could only deliver 25°C of cooling below ambient (at 100% power) in the longer term.

Camera Cooling - Earlier Session 2019-04-22, S676)

2019-03-23, S675
During session S675 (ambient temperature falling from +8 to +4°C) the camera was producing up to 28.7°C of cooling below ambient (at up to 83% power) to achieve a stable CCD temperature of -20°C. However at 02:57 the camera power levels jumped to 100% to maintain the CCD at the set point temperature. This was probably associated with an increase in ambient temperature.  Eventually the CCD started to rise to 0.5°C above set point. 

There seems  to be a subtle interaction at play.  When camera operates at 100% power it generates extra heat, which demands extra peltier cooling which it can't deliver as camera is already running at 100%,   and as a consequence the CCD begins to rise above set point.

Camera Cooling - Earlier Session 2019-03-23, S675)

2019-02-23, S667
During first half of session S667 (ambient temperature falling from +8 to +4°C) the camera was able to produce up to 28°C of cooling below ambient (at 80% power) to achieve a stable CCD temperature of -20°C.  A sudden but short-lived increase to 100% power level occurred at 22:50 and is unexplained.   CCD Camera / Session operating ok throughout.

In the second half of session S667 (ambient temperature falling from +4 to +0.5°C) the set point temperature was increased to  -25°C at which point the camera produced 28-28.5°C of cooling when operating at 100% power but this produced a CCD Temperature of only around -24°C  (i.e. ~ 1°C above set point). As the ambient temperature continued to fall the camera was finally able to deliever CCD Temperature of -25°C at 80% power level. The drop in power level from 100% occurred fairly quickly (< 3 mins).

Camera Cooling - Earlier Session 2019-02-23, S667)

2019-02-25, S668
During session S668 (ambient temperature falling from +7 to +2.5°C) the camera was able to produce 27.5°C of cooling below ambient (at 80% power) to achieve a stable CCD temperature of -20°C. Later on the camera produced 28°C of cooling below ambient when operating at 100% power when the temperature set point increased to an overly ambitous -25°C (which demanded up to 29.5°C of cooling below ambient, which the camera couldn't deliver)

Camera Cooling - Earlier Session 2019-02-25, S668)

 Conclusions

The ST-10XME camera seems only capable of 28°C of cooling below ambient (not as high as 30-32°C of cooling that it have sometimes been produced in the past).  This might be temperature or airflow dependant.  The lower value may be associated with the Dome Observatory (less airflow) instead of the previous Roll-Off Roof Observatory (more airflow).

Updated Settings for ProposeCcdTempSetPoint function (AstroMain 3.10.1)

Ambient = MonitorEnvTemperature

If Ambient < -4 Then            ' was < -2.5   in 3.10
  SetPoint = -30
ElseIf Ambient < 1 Then      ' was < 4
  SetPoint = -25
ElseIf Ambient < 6 Then      ' was < 9
  SetPoint = -20
ElseIf Ambient < 11 Then    ' was <14
  SetPoint = -15
ElseIf Ambient < 16 Then    ' was <18
  SetPoint = -10
ElseIf Ambient < 21 Then    ' was <24
  SetPoint = -5
Else
  SetPoint = 0
End If

Updated Formula is Fits_Summary.xls

Formula for CCD Cooling (was named Diff) modified to use UPB Env Temp instead of Tube Temperature

AdvMain 4.10.1

AdvMain modified to use new SetPoint settings

After stopping Observatory Services at 2019-01-18  23:13 (Laptop 9 running AstroMain 3.10.1,  with the TCF-S connection working normally up to that time)  the following error was encountered when the Observatory Services were restarted a couple of minutes later (23:15)

  Focuser 1:                  Fail      Unable to connect (Optec TCF-S)
  

This message is abnormal, the Focuser would normally reconnect ok every time. 

Examination of graphs and monitor files showed that the TCF-S went offline, or at least started give flat-line OTA temperatures, at around 15:00 (i.e. several hours beforehand).

A series of attempts were made to the reconnect to the TCF-S focuser over the next 24 hours but they all failed. 

- stopping/restarting Observatory Services (fail)
- closing/restarting AstroMain (fail)
- reselecting the COM 7 Port for the ASCOM.TCF-S Focuser properties screen  (fail)
- turning off/turning on the Computer (fail)
- turning off/turning on the TCF-S focuser (fail)
- alternate connection to the TCF-S via TCF-S Commander 6.0.6 (fail)
- disconnecting/reconnecting the USB cable between USB Hub and the USB-Serial adapter going to TCF-S (fail)
- using the USB cable in a different USB Port / different USB-Hub (fail)
- turning off/turning on the USB-Hub (fail)
- uninstalling the COM7 Device and allowing the device driver to reinstall itself upon reinsertion of USB cable (fail)

Various checks also failed to identify a cause to the problem :

- TCF-S operation from TCF-S Control Box (ok)
- Serial cable connection to the TCF-S control box and to Serial-USB Adpater plugged (ok)
- TCF-S control box switches in "PC Manual" and "Run" positions  (ok)
- COM Port appears in Device Manager (ok)
- USB-Serial device shows 'working ok' in Device Manager (ok)
- COM Port Drivers described as Latest in Device Manager (ok)

USB-Serial Port - Device Status (COM7)

Other error mesages given when attempt to connect to or use TCF-S from AstroMain
    Failed to find or connect to ASCOM Focuser1 (ASCOM.OptecTCF_S.Focuser)

    Focuser1:    Fail      The RPC server is unavailable. (Exception from HRESULT: 0x800706BA)

    23:15:59.27 | Exception Connecting to Focuser 1. Error: CheckDotNetExceptions ASCOM.OptecTCF_S.Focuser
    ConnectedSet System.Exception: Unable To Connect To Device. (See Inner Exception for details)

Screen capture showing error message when attempting to connect to Focuser using TCF-S Commander

The issue was deemed "Critical" and a forward plan developed in order to try to get back the observatory back to being operationally capable.

Foward Plan
 - Try connection using a different computer   (to rule out the computer, operating system, software setup and  USB HUB)
 - Try a different USB-Serial Adapter  (to rule out the adapter)
 - Try a different serial Cable  (to rule out the serial cable)

-  Finally, if become necessary, get a a new/replacement focuser.
   ( This would most likely be the TCF-Si version of the Optec TCF focuser (https://www.optecinc.com/astronomy/catalog/tcf/17668.htm)
    as it would allow power/comms via my Pegasus UPB PowerBox which would reduce the number of cables coming off the telescope by 2. )

Result
 - Attempted connection using a different computer (Laptop10)  failed (fail). 
    It was not possible to get computer to recognise the USB-Serial Adapter as a COM Port when it was inserted into a USB port.

 - Attempted connection using a different USB-Serial adapter worked (ok)
   The adapter was a spare one that was previously used for operating the LX200 telescope prior to installing a Pierro Astro USB-RS232 Cable connected via the Pegasus UPB.

Resolution
   Issue resolved 2019-08-20 18:00 by replacing the failed USB-Serial adapter with the spare one .
        (Connection was tested for 6 hours and then used in a live observing session, (2019-08-20, S00681) without further incident )