Appendix D : Troubleshooting & Maintenance

On Screen Message Meaning
"Sync failure on blocksize" or"Sync failure on data" The software was unable to read pixel data from the camera. Ensure the camera is switched on and connected. Try switching the camera off and on again and repeating the operation.
"Block size out of range" or "No room for block" These indicate a possible synchronisation problem with the camera's software and the computer's. Try switching of the camera and repeating the operation. If the problem persists please contact the LSR AstroCam hotline.
"Local transputer in error" "Host transmit FIFO not empty" "Host receiver FIFO not empty" These messages indicate possible problems with the camera interface card in the computer. They may also appear if the camera is switched off during an operation or the connecting cable has been removed.
"Unable to boot the camera" "Card not present at address xx" "Transputer in error" "Unable to install code "xx" into the camera (block x of xx)" "Failed on block n: " These messages may appear when the camera is being initialised ready for use. They indicate a possible problem with interface card or the connecting cable. Check that the interface card is installed and set to the correct address, check the cabling and check that the camera is switched on and then retry the operation.
"Unable to read AT Link initialisation code file "xx"" "Unable to read boot code file "xx"" "Unable to read codefile "xx"" "The Occam code files in use are version xx.This software is only compatible with version xx and above" These messages indicate that the named file cannot be found or is incompatible with this version of the PixCel software. These support files, which are used to operate the camera, should be present in the same directory as the PixCel software. If they have been accidentally deleted or corrupted then the software will have to be re-installed. You must backup the file PIXCEL.INI prior to re-installation.
"Invalid response packet" "Unable to flushmessage queue" "Unable to write message packet" "Unable to read message packet size" "Invalid message packet size xx" "Unable to read message packet data size xx" "Message packet requestxx never acknowledged by camera xx" These indicate communication problems between the camera and the computer. This will normally only occur when the connecting cable is disconnected or the camera is switched off during an operation.
"ADC bit weight is 0" "Time constant is 0" "Programmable gain is 0" "Integration time is 0" "Adc polarity is 0" "CCD gain is 0" These messages should never appear. If they do please contact the AstroCam hotline. They indicate that some of the parameters used to control the camera were incorrect. However these parameters are normally checked prior to use.
"Exposure interrupted by Escape key" "Wait for trigger interrupted by Escape key" These messages indicate that a selected function which will normally take a long time has been interrupted by pressing the "Esc" or "Escape" key on the keyboard.
"xx setting of xx not in the range xx to yy" xx setting of xx not in the selection [a, b, c ]" "xx unknown data type in cell [xx, yy, zz]" "Insufficient data for table xx" "Insufficient data for matrix xx" These error messages indicate invalid settings in the PIXCEL.INI file. Either use the "Configuration" option from the "File" menu to re-configure the software with corrected values or exit the PixCel software, edit the PIXCEL.INI file with a text file editor to correct the values, the re-start the program.
"If the camera is still completing the last operation please wait until the status bar reports 'Ready' " This error message will appear if you continue clicking or initiating actions before the previous action has completed. Click on OK and wait a few seconds before proceeding.
Miscellaneous problems Solutions
Cannot see or use all Camera tab features. Software window is too large for the screen. The screen resolution should be set to 1024x768. Change your PC screen settings in Windows 95 (Start/Settings/Control panel/Display). Maximize the size of the program window (Restore/maximise/ close toggle buttons in the top right hand corner of the screen).
Mouse cursor on the screen needs definition. The mouse cursor can be changed to give better definition by clicking on the Windows™ 95 Start/Settings/Control Panel. Double click on Mouse and choose Pointers tab. 'Precision Select' is the default setting although we advise 'Cross_1.cur' which has better definition for the PixCel software. If 'Cross_1.cur' is not available this will be because the Mouse pointers checkbox was not selected from the 'Accessories' options when installing Windows 95. Accessories can be re-installed by using 'Add/Remove' in Start/Settings/Control Panel with the original installation disks or CD.

Maintenance : Camera head

The only routine maintenance required for the camera head, is to ensure the optical path is kept clean. Under normal circumstances this will involve removing any dust on the window of the camera head with a good quality 'cotton-bud' moistened with a non-aggressive solvent such as Isopropyl alcohol.


On some heads, access to the CCD window is through the shutter on the front of the camera head. The easiest way to open the shutter is by setting a long exposure time, say 1000 seconds, and grabbing an image. When cleaning is complete the exposure can be aborted by clicking on the Stop button. No damage will be caused to the CCD by this over-exposure.


The camera head for cooled systems can lead the front window to be fractionally cooler than ambient air temperature. Under conditions of extreme humidity, condensation can form on the front window. This must be dried carefully. Moisture must not be allowed onto the shutter blades which will be damaged if operated damp.

WARNING: Three things to be careful of when carrying out this exercise.

  1. Only clean the front window of the camera head. Do not touch any of the CCD contacts around the edge of the device (for uncooled cameras only).
  2. Take care not to knock or move the shutter blades as this may cause the shutter to malfunction.
  3. Do not get the Isopropyl alcohol or any other liquid onto the shutter blades. They are very delicate and the liquid will cause the blades to stick together.

Any problems or queries should be directed to your local distributor or the LSR AstroCam Hotline on Telephone no: +44 1223 424353, Facsimile no: +44 1223 840342 or Email on


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