The D40 Camera is a trusted radiation tolerant video camera that is relied-upon by the nuclear industry for IVVI, MRP, core verification, fuel inspection, FOSAR activities, cask loading, and more. But without sufficient maintenance and proper operation, it may not provide its optimal level of performance. The following are 3 easy ways to ensure that your D40 cameras are working at 100%.
1.) Use a Good Tube
The CRT tube is the single most important component to optimal camera performance. If the tube in your camera has been exposed beyond its dose limit, has been left idle for too long, or has been flooded or damaged, it may not produce an image of the appropriate quality. Effects may be visible as reduced resolution, excessive smearing, blooming, or reduced sensitivity.
If a tube/camera has been left un-energized for a period of 5 months or more, and exhibits poor focus or oversaturation, it is necessary to “train” the tube. Do this by leaving the camera powered-on for 8 hours with the lens cap on, and the internal lights turned off.
Curing image burn-in
Also, much like a CRT monitor, there is potential to “burn” a ghost image onto the tube if a camera was left stationary while aimed at a bright, non-uniform scene. Depending on the severity, this can usually be remedied by aiming the camera at a bright light, and cyclically “scanning” the camera so that all portions of the video image get aimed at the light for a roughly equal amount of time. Usually within a few minutes the image burn effect can be completely mitigated.
2.) Remember to Set the Dynamic Focus
Although much of the D40 system is digital, the camera unit contains analog circuits so that it is able to provide its extremely-high radiation tolerance. As a result, there can be very subtle electrical variations between different cables, cameras, and tubes. These differences are compensated by adjusting the dynamic focus setting on the D40 controller. This setting fine-tunes the focus of the beam of electrons within the tube.
The dynamic focus is adjusted via a screw pot on the controller’s sweep generator module. Although your system will likely work just fine without ever touching this adjustment, for the absolute best possible image quality it is recommended to tweak this any time an element of the system is swapped-out.
Adjusting dynamic focus
To set the dynamic focus, power-on the D40 system as you would normally, and aim the camera at a resolution chart about 12” away. If a resolution chart is not available, you can substitute a glare-free object with fine detail. First, get the optical focus as sharp as possible. Then flip down the controller front panel, and turn the dynamic focus pot using a small slotted screwdriver until the focus is as sharp as possible. Then go through a couple more cycles of alternatively adjusting the optical and the dynamic focus, until the video image displayed is at 600+ lines of horizontal resolution. (NOTE: Do not turn the adjustment pot more than 1-2 turns in either direction)
3.) Perform Regular Maintenance
Acrylic window
As with all tools and equipment, for consistent, reliable camera system performance, it is recommended to perform regular preventative maintenance. Replace acrylic port windows if they have browned or become embrittled. Take good care of your umbilical cables to ensure they are not bent inside the minimum bend radius – this can damage the internal coax conductors, leading to bad video quality. Check the cable jackets for cuts or breaks – if the cable floods, water can make its way into the camera. And take care to regularly replace and lubricate o-rings to maintain the housing’s hermetic seal.
For additional technical information or guidance on how to keep your camera system working to its fullest, please email support@diakont.us.com or call us 24/7 at 858-551-5551. We have tubes and replacement parts on-hand for immediate shipping, and are scheduling field support and operational/maintenance training sessions for Fall 2011 and beyond.
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