Cooling
CCD Camera Thermoelectric Cooling
A second source of generated heat is the CCD Camera.
The CCD chip in the camera generates considerable heat as it helps
create video from the visible light images on the Image Intensifier output phosphor. A themoelectric cooler (TEC) heat sinked to
the back of the CCD chip helps keep the chip cool enough to perform in its linear region and avoid damage. The TEC is actually a
solid-state heat pump that draws heat from the CCD and transfers it to a heat sink. If the CCD Camera is not cooled, the “dark”
current will increase. That would result in greater fixed paattern defects. However, white dots may appear due to failure of the
offset correction hardware on the Video Control PCB, or software.
The TEC requires +5 Volts at about 2.5 watts to adequately cool the CCD. The Power/Motor Relay PCB
receives +12 Volts from
Power Supply PS1
through a voltage-dropping array to produce the +5 Volts.
The +5 Volts is sent from the Fluoro Functions PCB to the TEC. A Field Effect Transistor turns power to the TEC on and off under
software control. TEC is mostly off after system boot-up. The on/off algorithm under softare control increases the on time (duty
cycle) so that more cooling takes place the longer the system is booted.
4
Service
Periodic Maintenance
Contents
Schematics
Illustrated Parts
Installation
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